Datasets:

bshada

/

electronics.stackexchange.com

like 0

1530

|soldering|surface-mount|pcb-assembly|

<blockquote> <p>Passives 0805 or larger</p> </blockquote> <p>IMO Less important than the size of the packet is the ammount of space arround it. Given the choice I would rather have an 0603 with plenty of space arround it than 0805 parts crammed up next to each other.</p> <p>I would also suggest generous pad sizing. It's much easier to hand solder if the pad goes beyond the end of the component.</p> <blockquote> <p>Min Lead Pitch for SOIC or QFP -- 0.5mm</p> </blockquote> <p>This is IMO getting to the point where it is too small to reasonablly solder pin by pin. Blob dragging or flood and wick techniques can work but require a fair bit of practice.</p> <p>Sometimes you may have no choice but if a larger pitch is available I would suggest choosing it.</p> <p>I would also suggest lengthening the pads so they stick out further beyond the chip than commercial pads do. This will make the pads more robust and make it easier to heat pad and leg at the same time with an iron.</p>

<p>More components are only available in SMD packages. For hobbyist assembly the options are to buy breakout boards or solder SMD.</p> <p>Since components are usually packaged in a couple of SMD package types I am trying to put together a set of guidelines for choosing packages that are compatible with hobbyist skills and tools. I would consider hobbyist level tools for SMD assembly as -- soldering iron in the $50-$100 range (new), for magnification a $40 visor (like the B&amp;L) and tweezers.</p> <p>For the kits I make now I use the following guidelines --</p> <ul> <li>Passives 0805 or larger</li> <li>Min Lead Pitch for SOIC or QFP -- 0.5mm</li> <li>No QFN, LGA or BGA</li> <li>Prefered package for gates, BJT, FET --- SOT23</li> <li>Diodes SOD123 (or larger)</li> </ul> <p>I am interested in recommendations on component selection, minimum tool requirements and assembly issues. Specific tool changes (like solder tip size) that enabled you to do SMD assembly with your existing tools would be useful too.</p> <p>Thanks.</p>

Sizing SMD components for Hobbyist Kits

2010-01-26T17:32:59.633

1531

|connector|

<p>Those are headers and receptacles. </p> <p>The parts in the pictures look like the common 2mm battery connectors made by JST. If those connectors will work then I would search for JST and 2 pins and 2mm pitch. The exact pn's for the TH parts should be</p> <ul> <li>B2B-PH-K-S for a top entry header</li> <li>S2B-PH-K-S for a side entry header</li> <li>PHR-2 for a cable mount recptacle (without contacts) The contacts are SPH-002T-P0.5L for the 24-28AWG crimp</li> </ul> <p>You may want to double check those pn's at Digikey and Mouser.</p> <p>Connectors are one place where all the search engines fall short. The printed catalog can sometimes be a lot quicker.</p>

<p>I need a really small 2-pin connector, a cable connector on one side, and a surface-mount jack on the other. These two items at AllElectronics are pretty close:</p> <ul> <li><p><a href="http://www.allelectronics.com/make-a-store/item/SBC-1/SMALL-BATTERY-CONNECTOR-WHITE/-/1.html">Small Battery Connector, 2mm spacing</a></p></li> <li><p><a href="http://www.allelectronics.com/make-a-store/item/SBH-1/HEADER-FOR-SMALL-BATTERY-CON-2MM-SPACING-WHITE/-/1.html">Header for Small Battery Connector</a></p></li> </ul> <p>What is the general name for these two items, so I can search Digikey or Molex? And anyone know the exact part numbers of the above parts? (AllElectronics doesn't know)</p> <p>Update:</p> <p>As per jluciani's awesome answer, these are definitely JST parts. Mouser doesn't carry JST, but <a href="http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&amp;name=455-1704-ND">Digikey does</a> as does AlliedElec. And it looks like <a href="http://www.jst.com/">JST</a> makes SMT variants of the PCB mount header as well as small pitch connectors too.</p>

Help with connector part numbers

2010-01-26T19:16:30.663

1537

|arduino|

<p>Thanks all who contributed. My code works and I have learnt about hardware serial, rf comms, software serial, cast, floats, serial LCD and dallas onewire all in 2 days :-)</p>

<p>been using picaxe for a few years but now playign with arduino and trying to learn how it all works.</p> <p>I have a couple of arduinos talking via the HOPERF library successfully and now want to send some meaningful data over the link.</p> <p>I have the code for the DS18B20 running on the client aurduino and "printing" the temp value to the PC via USB but just not sure how to get it into the HOPERF commands to send over the RF. Here is a bit of the code. The 2nd line is where the data is sent over the HOPERF. What i need to do is replace the string "test" with the data returned by the (sensors.getTebyCByIndex(0)) command from the 4th line.</p> <pre><code>sensors.requestTemperatures(); // Send the command to get temperatures client.sendto(11, (uint8_t*)"test\n", 6); // Includes the NUL at the end of the string Serial.print("sending\n"); Serial.print(sensors.getTempCByIndex(0)); //prints the temp value over the USB </code></pre> <p>Any clues anyone?? I prefer to learn but doing stuff like this - and yes i did do the "BLINK" thing first! I find doing something i find useful helps me learn faster :-)</p> <p>I am struggling a bit with working out the docs as there doesnt seem to be a nice "manual" liek the picaxes to follow :-(</p>

newbie code query => Arduino & DS18B20

2010-01-27T07:49:32.573

1552

|arduino|motor|

<p>They should be controlled by pwm, in particular the same pwm that is used for servos. Typically built in pwm units are not accurate enough, instead interrupt driven timer routines are usually the way to go. Should be lots of info on the web for arduino and servos.</p>

<p>This may be a lame question but, Speed controllers on big RC cars can they be controlled from Arduino? If yes, do they have a standart? do I control them using PWM values? What should i look for if I am going to buy one?</p>

Arduino Speed Controllers for RC Cars

2010-01-29T17:21:00.293

1561

|motor|mount|

<p>An H-Bridge is a circuit that has 4 transistors (2 PNP and 2 NPN) that will control a single motor in 4 states (forward, reverse, coast, and braking). Can use bipolar transistors for low(hobby) power up to about 500ma or MOSFET transistors for more power. You can buy H-bridges preassembled but spendy. My 2004 copy of "Intermediate Robot Building" by David Cook has a good explanation in Chap 10 and 11 of H-bridges. Lots of H-bridge explanations on the net. chris-m</p>

<p>How do I incorporate a hobby-style motor into a project, physically. How do I mount it and connect a wheel to it? (Assume that I have a working H-bridge or even switches, and am not concerned about how to use the motor electrically, just physically.)</p> <p>I've purchased small, hobby style motors at various times. Typically, they run on 1.5 V to 12 V, and many of them have no built-in gearing (and thus spin really fast with very low torque). How do I connect a wheel to it, or a gear or pully?</p> <p>Next, most motors of this sort are round. Round! If it was flat on one side, I could glue it down. It looks like they are designed to be screwed into something at the front or back, but I don't know how I'd make a surface to mate to it nor make marks to drill holes through it precisely enough. </p> <p>What have you found works for when you want to make an electronics project move around on its own?</p>

How do I physically work with a hobby motor?

2010-02-03T17:00:45.363

1563

|arduino|avr|avrdude|prototyping|

<p>It sounds like you've already got an AVR ISP programmer and you're just looking for something to go from that to the AVR. Adding the ICSP header to your project is easy, but if you don't want to do that, I'd suggest checking out the <a href="http://evilmadscience.com/tinykitlist/74-atmegaxx8" rel="nofollow">Simple AtmegaXX8 Mini Dev kit</a>. I'd get the version with the ZIF socket included - it's much easier to work with than a traditional socket.</p> <p>Alternatively, you can <a href="http://www.evilmadscientist.com/article.php/avrtargetboards" rel="nofollow">wire your own</a> up on a piece of protoboard pretty easily, though again I'd suggest getting a ZIF socket. <a href="http://www.sparkfun.com/commerce/product%5Finfo.php?products%5Fid=9175" rel="nofollow">Sparkfun</a> has the cheapest ZIF sockets. You'll probably also want to add a crystal (<a href="http://www.sparkfun.com/commerce/product%5Finfo.php?products%5Fid=538" rel="nofollow">Sparkfun</a>) since the ICSP won't work without one if you've set the fuse bits to expect an external crystal (so having one means it will always work).</p>

<p>I have an Arduino (NG) board with an ATMEGA168 AVR micro. The board has a 6 pin ICSP header. Here is what I propose to do, please tell me if it is possible:</p> <ul> <li>Remove current ATMEGA168 IC</li> <li>Replace with a new AT AVR of similar series</li> <li>Plug in the programmer to the ICSP header on the Arduino</li> <li>Use avrdude software to program the AVR</li> <li>Remove AVR and install in a socket on my project board and replace the original ATMEGA168 AVR</li> <li>Continue to use the Arduino as normal</li> </ul> <p>I have also thought about installing the 6 pin ICSP header on my project board so I can tweek the software with the chip in place. If I implement this part of the arduino circuit on my project would this be possible.</p> <p><a href="http://mintmedia.co.nz/File:ATMEGA168%5FICSP%5Fschematic.png" rel="noreferrer">Schematic</a></p>

Using Arduino to program Amtel AVRs via ICSP header

2010-02-03T23:50:50.950

1575

|board|cases|enclosure|

<p>If you mean prefabbed with bezel and all, I am not aware of any. I have used some standard project boxes for my phidget projects and they work pretty well. They just take a little work. I use a dremmel to carve the openings.</p>

<p>Are there cases for Phidgets IO boards such as the <a href="http://www.phidgets.com/products.php?category=0&amp;product%5Fid=1019" rel="nofollow">1019</a> ?</p>

Cases for Phidgets boards

2010-02-08T16:43:15.937

1586

|avr|linux|

<p>Avrdude works just fine on OSX too. Just,</p> <pre><code>port install avrdude avr-gcc avr-binutils avr-gdb avr-libc </code></pre> <p>And you're ready to do everything that WinAVR does.</p>

<p><a href="http://www.sics.se/%7Eadam/contiki/docs-uipv6/a01107.html" rel="nofollow">This tutorial</a> starts with programming the Ravens and Jackdaw with a Windows box. Can I do those initial steps with a Linux or OS X machine instead? If so, how? Is there any risk of bricking the hardware if I just try? </p> <p>I have a USB JTAG ICE MKii clone, which is supposed to work for this.</p> <p>I'm totally new to AVR, but very experienced with C/C++ programming on Linux or OS X, up to and including kernel programming.</p>

How do I program an AVR Raven with Linux or a Mac?

2010-02-11T06:36:32.967

1587

|current|

<p>You are good to hook it up without any other circuit, although a fuse is never a bad idea. It is actually to prevent damage to the wiring or other devices in you car in the event your device shorts out. </p> <p>Unless there is a defect in your circuit it will never consume more than the 1 watt it is rated at. Are you sure the rating you looked at didn't say a "minimum power supply rating" instead of maximum? Most likely it was stating the maximum power the unit would consume.</p> <p>Don't loose sight that your unit will be draining the battery if you are not running the car unless you hook it up to a switched circuit.</p> <p>Good luck.</p>

<p>I am a programmer with only basic understanding of electronics/electricity.</p> <p>I am trying to install <a href="http://www.teltonika.lt/en/pages/view/?id=955" rel="nofollow">this device</a> into my vehicle. The device accepts a wide DC power input (10V to 30V), but has a maximum power supply rating of 12W <em>(Edit: had typed 1W)</em>.</p> <p>I am assuming that means the input current should be somehow controlled, external to the device.</p> <p>What do I need to do this? A <strong>current limiting circuit</strong>? A fuse for extreme situations?</p> <p>A current limiting circuit as described in wikipedia will dissipate power? Are there off-the-shelf components for this?</p> <p>Is a separate spike guard required?</p>

How to supply power from vehicle to a low power device?

2010-02-11T11:00:51.367

1594

|simulation|

<p>You can start designing your circuit on a Circuit Simulator. You can learn Spice Circuit Simulations Using LTspice. LTspice is available free from Linear Technology. LTspice is perhaps one of the most widely used free simulators. It is a powerful simulator with a simple interface to handle. For learning LTspice You can refer to the following link: <a href="http://rads.stackoverflow.com/amzn/click/1508649219" rel="nofollow">Electronics circuit Spice Simulations</a></p> <p>There are also <a href="http://www.simonbramble.co.uk/lt_spice/ltspice_lt_spice.htm" rel="nofollow">numerous</a> <a href="http://www.linear.com/docs/39806" rel="nofollow">free resources</a> <a href="http://denethor.wlu.ca/ltspice/" rel="nofollow">available</a> <a href="http://www.allaboutcircuits.com/technical-articles/intermediate-ltspice-tutorial/" rel="nofollow">online</a>.</p>

<p>For the last few days I have been trying without any luck to find a good tutorial on simple circuit simulations. I am a relatively new hobbyist and I figure if I use simulations and play around the circuit and see the output I would learn more. Can you please direct me to a simple tutorial which teaches simulation of circuits.</p>

Simple Circuit Simulation tutorial

2010-02-13T16:40:31.007

1604

|arduino|motor|power-supply|dc|

<p>If you are sure of the motor voltage and currents and all the motors may need to be on at the same time you really want two voltages.</p> <p>Using a single a 7V supply you would need to drop 4V to power a 3V motor. 4V * 1.17A * 6 motors = 28W. That is a lot of power to dissipate. </p> <p>You can get dual output wall warts. Get one with a 7-10V output and a 3-5V high current output. If size is not a factor you could get a PC power supply. Use the 3.3V for the motors and use the 12V for the Arduino with an regulator to drop the voltage to 7V or so.</p> <p>You could also get a single 3.3V supply and use a boost converter to generate 7V. It would be a small boost converter since the Arduino wouldn't need much power. These are easy to build. Something like a MAX34063 or LT1302 would work.</p> <p>I would do the boost converter solution.</p> <p>One more note -- I would not use Darlingtons to drive the motors. Darlingtons have a very high saturation voltage and you are going to dissipate a lot of power. A better choice would be a MOSFET. The IR IRLB8748PBF is a 40A MOSFET with an Rds(on) of 7mOhms (at logic levels). At 1A you will dissipate around 7mW compared to over 1W in the Darlington. They are about 90cents from Digikey.</p>

<p>Here's the circuit I'm working on, it's a robotic stringed musical instrument thing, that uses 6 DC motors and an Arduino Duemilanove - </p> <p><img src="https://i69.servimg.com/u/f69/14/39/80/39/pictur10.png" alt="Circuit"></p> <p>The resistors are 0.25w 1KΩ The transistors are TIP122 Darlington PNP The diodes are N5401</p> <p>The motors require 3v and 1.17A each, but the Arduino likes to work on about 6v-9v and only a few mA. I'd like to know the easiest way to use a single DC power supply unit (Of any appropriate spec), to power the whole circuit. </p> <p>Cheers.</p>

Can I combine the power supply?

2010-02-15T20:16:49.963

1609

|arduino|led|tutorial|

<p>If using digital LEDs such as WS2812 aka "Neopixels", a standard Arduino Uno can control up to 600 RGB pixels, without having to multiplex anything :)</p> <p>The only limitation here is the RAM of the board. A board with more RAM, such as an Arduino Mega that has 8kb of RAM can control up to 2400 pixels, when compared to an Uno which has only 2kb of RAM.</p> <p><a href="https://i.stack.imgur.com/joZOV.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/joZOV.png" alt="enter image description here"></a></p> <p>You can find a nice overview here: <a href="https://www.eerkmans.nl/powering-lots-of-leds-from-arduino/" rel="nofollow noreferrer">https://www.eerkmans.nl/powering-lots-of-leds-from-arduino/</a></p> <p>And more info on how to work with Neopixels here: <a href="https://learn.adafruit.com/adafruit-neopixel-uberguide" rel="nofollow noreferrer">https://learn.adafruit.com/adafruit-neopixel-uberguide</a></p>

<p>I want to use a regular Arduino board to control LEDs - what is the most lights I can control individually from the board?</p> <p>Is there a tutorial on how to hook it up?</p>

How many individual lights can an arduino control

2010-02-16T02:20:03.450

1612

|stepper-motor|motor|reverse-engineering|

<p>Steppers get marked like other motors, but they aren't operated like other motors. Your motors, depending on size, might have two or three heavy coils in parallel. This drives the resistance down to 1 or 2 ohms. At 100% duty, this gives them a nameplate rating of 3 or 4 volts. But, in actual operation, you don't use 100% duty. When you are running, the coils are at 50% duty or lower. When at rest, you usually switch them off or go to a 10% holding current. So to run them at high speed and/or high acceleration, the packaged drives use a high voltage (somewhere between 24 and 90 volts) and a current limiting resistor. This overcomes the internal inductance to give a snappy response. It's not plan B, it's just the way they work.</p> <p>So, the critical part of the nameplate is the temperature rating. It's usually around 120F. If you can keep your hand on it for a half second or more, then you're fine.</p> <p>But acceleration and deceleration is important, too. You usually can't just jump in a full speed. So you best bet might be to find a mill control box that has the drives and a control computer that does the profiling that you want. </p>

<p>I recently bought a CNC mini-mill at an auction. It is fitted with steppers on the three axis. The X and Y are the same, and the Z is a bit smaller (physically). All the markings were removed from the motors and they are painted flat black. Yet another reason to hate proprietary hardware. The machine was originally designed to use a custom controller which is missing. </p> <p>My question is, can I figure out what voltage the motors were intended to run at? Does the coil resistance offer any clues? I have a good quality multi-meter, and I have already reverse engineered the wiring. I don't want to fry the motors though.</p>

Is there any way to determine the correct voltage for a stepper motor?

2010-02-16T17:32:52.037

1616

|wireless|embedded|

<p>For wireless comms inside a house, the Nordic nRF24L01+ chips (modules available from Sparkfun) or the TI CC2500 (modules available from TI) are ideal. They are quite cheap.</p> <p>The TI modules actually come with sensor network software that is easily adapted for a particular application.</p> <p>Leon</p>

<p>I remember with fondness the X-10 days, when you could connect your computer to every wall plate in your house, using power-line carrier to transmit signals to addressable receivers (with varying degrees of success).</p> <p>OK, so maybe I don't need to turn on my microwave from my computer remotely, but I still think it would be cool to have a wireless controller scheme for some home automation, maybe even put a webcam on my Roomba, or some temperature sensors outside.</p> <p>What is a sensible overall way to approach this? Wifi endpoints are really attractive, but they seem a little pricey. Are there alternative approaches using radio? Or is power-line carrier still the way to go?</p>

What is a sensible approach to connecting devices to your computer via wireless technology?

2010-02-16T23:50:40.550

1620

|lcd|computers|

<p>you can use a Universal LVDS LCD Monitor Driver Controller Board like this <a href="https://i.stack.imgur.com/fnav6.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/fnav6.jpg" alt="enter image description here"></a></p>

<p>I have a 17" laptop monitor with a 1920x1200 (WUXGA I beleive it's called? or just UXGA?) resolution which I simply love. Now, assuming the laptop dies before the monitor does, would anyone know if it would be possible to salvage the monitor? Are the interfaces somehow standardized (can I simply solder some cable to a DVI connector and plug it in, more or less) or do they all depend on make and model? I'm guessing the power supply will be the least of my problems..</p> <p>In this particular case, it's a Dell Inspiron 9300.</p> <p>Thanks.</p> <p>Wasn't sure how to tag it, and 'new users can't create tags', so sorry about that. :)</p>

Reusing laptop monitors

2010-02-17T19:04:16.423

1630

|batteries|power|

<p>There are a number of ICs that will do these functions. I would go to the Maxim and Linear Technology sites. The downside is that most of these devices is that they are only in surface mount packages and a lot of them come in packages without leads (QFN, LGA).</p> <p>A part like the LTC4088 is nice. It has an input for the battery, an input for the USB (or wall adapter) and a switching regulator. </p> <p>You could also use separate ICs (but you are probably better off with a single). There is a device that Linear Tech calls a PowerPath controller (LTC4412) that performs the switchover function. You could add a MAX1555 Li-ion charger for a low cost charger and add the LTC4412. Also there are devices called "Ideal Diodes" that will perform switchover. These devices are FETs so you get a much lower voltage drop than a Schottky. </p> <p>The best solution depends on a couple of things you haven't mentioned -- system current, battery capacity and recharge rates.</p>

<p>Many people seem to run their projects off the mains (e.g. with a wall wart) or from a battery, but there doesn't seem to be too much discussion about how to run a device off the mains, charging a battery, but then switching over to the battery in the event of a power outage.</p> <p>I imagine that with NiCD/NiMH batteries you could just hook them up in parallel with the power supply (more or less), however since LiPo batteries hold more power for their size I would like to use them instead in a project like this - but they don't seem quite so simple to use in this way!</p> <p>Can anyone offer some pointers as to how LiPo batteries might be used for backup power? I imagine you would need some logic to power a charger and switch over to the batteries when the mains disappears, but I'm not sure how this might work. I imagine you'd also need a large capacitor to avoid a momentary dropout during the switch over as well. Or perhaps there's some cheap IC that can do all this for me?</p> <p>Thanks for any suggestions!</p>

How might you use a LiPo battery as backup for mains power loss?

2010-02-18T13:58:33.243

1635

|oscilloscope|

<p>The best scope for beginners is hands down Rigol 50Mhz scope, I used it for professional and hobby projects. You can buy below 350$, it has math function, two channels, can be hacked to support 100Mhz, digital filter, a decent size memory, USB capture etc. etc. Cannot say enough about it, it is really good. It has an antialiasing problem at 1msec but you can work around it. </p>

<p>I'm learning electronics (and basic electricity) and I wondered if a 1MHz oscilloscope like the <a href="http://www.seeedstudio.com/depot/micro-digital-storage-oscilloscopedso-nano-p-512.html">DSO Nano</a> is enough for (very) basic electrical and/or electronic circuits. I'm almost broke and I need a cheap portable oscilloscope to try various circuits (wherever I am, hence the required portable property) with resistors, capacitors, transistors, and microcontrollers (if I study hard enough). I don't thing I need a more powerful oscilloscope because I'm learning and I'm just following the exercises in various books right now. This would be my first oscilloscope and I would eventually buy a 20MHz portable oscilloscope later.</p> <p>Thank you!</p>

Cheap 1MHz oscilloscope

2010-02-18T16:23:19.933

1643

|eaglecad|power-supply|components|power|

<p>On-Semi is a second source for this part. There may be some additional information at <a href="http://www.onsemi.com/PowerSolutions/product.do?id=LM2575" rel="nofollow">http://www.onsemi.com/PowerSolutions/product.do?id=LM2575</a> </p> <p>Are you choosing the LM2575 because you want a through hole buck converter? If you can do SMD parts there are parts that offer much better performance. A higher frequency part will let you use much smaller capacitors and inductors.</p> <p>TI also makes some buck converter modules (TH packages) that are very inexpensive. Checkout the PTR and PTN series devices.</p>

<p>Can anyone suggest a 330uH inductor and associated Eagle .lbr for use with an LM2575? </p> <p>I've been looking all day for this! Any suggestions would be appreciated.</p>

Inductor for LM2575

2010-02-20T10:10:32.170

1647

|audio|detection|

<p>While audio jacks often have switches that can be used for plug detection, most codecs now implement jack sensing that measures the impedance and other characteristics of the plugged in device and make that information available to the processor they are connected to.</p> <p>This is also very helpful in preventing an audio amplifier from trying to drive speakers outside its impedance range and damaging the amp or the speakers.</p>

<p>Some sound card audio jacks can now inform recent Windows OS's that an audio device is plugged in. Anyone know how it does this? I'm thinking it uses some kind of voltage comparator or resistance measurement.</p> <p>This question was asked at <a href="https://superuser.com/questions/110933/how-does-a-sound-card-determine-if-headphones-are-plugged-in">Superuser</a>. My gut feeling is that the circuit is not as trivial as one of the participants is suggesting, but I'm a bit rusty on circuits.</p>

How does an audio jack detect when a speaker is plugged in?

2010-02-20T23:28:19.073

1654

|communication|uart|power-line-communication|

<p>It is done in telephone systems. As you know in telephone we have power and dialing tone and voice in a two-wire system. You can send your commands through power line by generating tone (like tone dialing in ordinary telephon) the integrated circuits (Ic) for this application are commonly used and therefore are very cheap.</p> <p>I did a project like this for controlling water valves in a large plant in Iran (up to 99 valves). I can add a block diagram of my coder decoder circuit if you think it may be useful.</p>

<p>I'd like to be able to daisy chain multiple devices using just the power supply wires and then inject a communications signal over the power lines to turn it into a half duplex network.</p> <p>Are there any common methods of achieving this? The simpler the better and it would be great if it used the UART on the microcontroller.</p> <p>Edit: There are actually two projects that I'm working on that I think would benefit from this - one is a low power sensor network. The other is a LED lighting project. In both cases the objective is to simplify wiring, but if the solution is too complex then it probably makes more sense to use three wires (pwr, gnd, comms).</p>

Injecting a communication signal over DC power supply lines

2010-02-22T00:29:17.460

1663

|computers|microcontroller|embedded|

<p>Remote serial and jtag access for embedded development. Instead of paying for pricy networked jtag devices you can get an plug computer, a few usb to serial converters and a few amontec or other ftdi based jtag wigglers and get a lot more bang for your buck.</p>

<p>Are <a href="http://en.wikipedia.org/wiki/Plug%5Fcomputer" rel="nofollow">plug computers</a> useful for anything besides network-attached storage?</p> <p>I know that you can hang a bunch of drives off them, maybe set up your own web server. But those uses have limited attractiveness in a home environment, and in a corporate environment, I suspect that ordinary servers would be used. I could see them used in an industrial environment, perhaps as environmental controllers or energy management devices, but the lack of I/O (keyboard and display) appears to limit their usefulness.</p> <p>Am I missing something? Or do I simply lack imagination? Do you envision a way to use these in a home environment, other than as a media server/poor man's Tivo?</p>

What are some of the more compelling use cases for plug computers?

2010-02-22T19:34:31.793

1668

|schematics|communication|

<p>We print to Adobe and use its review features of the full edition.</p>

<p>So a friend and I were talking about schematics at work and how we can better communicate among us and our co-workers. I know <a href="https://electronics.stackexchange.com/questions/1024/uploading-schematics-for-chip-hacker/">Kortuk had asked a question previously</a> that was similar, but that question was more about how to make the schematics.</p> <p>Instead, I'm now asking if anyone knows a good way to collaborate on schematics that are already complete. Kind of like the <a href="https://electronics.stackexchange.com/questions/1024/uploading-schematics-for-chip-hacker/1026#1026">"Google Docs for Schematics" I talked about in response to Kortuk's question</a>. I have a bunch of schematics in pdf form that I want to be able to mark up and show to someone with a link as opposed to sending it to them. I also want the content to be secure and probably on an internal server.</p> <p>I think what I really want is a wiki plugin that would allow me to do something like this. Has anyone heard of any program that could achieve something like this?</p> <p>FYI, I've seen software such as <a href="http://a.nnotate.com/index.html" rel="nofollow noreferrer">a.nnotate</a>, but don't know if I can swing the price they ask (to keep it behind my firewall). So I'd appreciate open source but am willing to pay something.</p>

Sharing and Notating Schematics?

2010-02-23T17:08:25.300

1669

|batteries|wireless|

<p>Try LiFePO4 rechargeable batteries. You can get them in 18650 form-factor on eBay or Aliexpress, there are matching sockets with wires attached for sale, too.</p> <p>Notice that these cells need lower charging current than typical LiIon - 3.6 — 3.65 volts instead of 4.2 — 4.23 volts.</p> <p>Cyclists use these in winters for flashlights - even at -20C a fully charged cell can release about 50% of its nominal capacity before voltage drops below critical 2.7V</p>

<p>I've built a temperature sensor module that runs off of 4xAA batteries and sends data back to a computer via XBee. Works great, until the weather gets cold. At that point, the rechargeable AA batteries (I've tried duracell and eneloop) die very quickly. At 40 or so it seems like they can hardly muster the 3.3V needed to power the wireless.</p> <p>This needs to be battery powered - running a wire to it isn't an option.</p> <p>I'm trying plain old alkalines right now, but I was wondering if anyone had any tips on getting enough power out of batteries during the winter. Do I just need to double up and use 8 batteries? Do NiCad or LiPo cells work better than NiMH? Would switching to a different wireless module that can handle lower voltage solve the problem?</p>

Cold weather battery power

2010-02-23T17:53:26.050

1674

|schematics|cad|pcb|

<p>Google and Antmicro recently launched the <a href="https://opensource.googleblog.com/2022/02/FPGA%20Interchange%20format%20to%20enable%20interoperable%20FPGA%20tooling.html" rel="nofollow noreferrer">FPGA Interchange format</a> which includes a standard for describing logical and physical netlists.</p>

<p>Is there a common netlist format that is portable between different schematic/pcb/EDA/CAD tools, and if so where is the format or reference so I can implement it?</p> <p>If not, does each package implement it differently, or are there a few standards that, if implemented, might give greater compatibility with a broad range of tools?</p>

Is there a common netlist format?

2010-02-23T21:07:46.460

1689

|uart|communication|rs232|

<p>RS232 voltage-level signaling is becoming less common, as more and more devices are designed to plug into a USB port rather than an RS-232 port. The common async 8-N-1 signaling protocol, however, allows data to be sent full duplex with predictable timing and no byte stuffing. A byte can be started at any desired moment when the line is otherwise idle, and there is no danger of data underrun. Hardware to support 8-N-1 signaling is common and cheap, and while the protocol isn't entirely optimal, many changes that would make it better for some applications would make it worse for others. The only significant downside to 8-N-1 is that it requires that both sides of the communication have a stable clock which is a known (generally integer) multiple of the desired communications rate.</p> <p>Incidentally, most async 8-N-1 hardware allows for at least one type of out-of-band signalling: the long break. While there are certainly times it would be helpful to have a few more types of out-of-band signaling, it's useful to have at least one.</p>

<p>Are there any alternatives to this ancient yet still popular way of communication?</p>

It's been more than 10 years (since I designed hardware with RS-232), and we're still using RS-232?

2010-02-25T14:31:07.060

1697

|microcontroller|freescale|

<p>Last fall Freescale came out with a great beginner's eval board - the Freescale FRDM KL25Z. It is about $13 US and there is an excellent tutorial based website for it at mcuoneclipse.com.</p> <p>You can't go wrong giving the FRDM board and website a try.</p>

<p>Which websites/blogs/tools/books/manuals would you recommend for getting into the Freescale microcontrollers, especially the 32-bit models?</p> <p>What are the best development tools (IDEs, compilers) for this environment. There is so much out there for the AVRs, ARMs, PICs but not too much for Freescale. I admit, I need to spend more time with Google on this and just thought I'd save myself plenty of time by asking the "experts".</p> <p>Thanks</p>

How to get into Freescale 32-bit MicroControllers?

2010-02-26T07:55:52.210

1709

|digital-logic|

<p>Its a 2:1 multiplexer, the select input being B. A and C are inputs, D is the output</p>

<p>I need help confirming some hunches. I'm trying to figure out what type of circuit this is:</p> <p><img src="https://i.stack.imgur.com/DMBwi.jpg" alt="diagram"></p> <p>Any ideas?<br> Also, I think the logic expression for this is: <code>D = (A AND B) OR (NOT(B) AND C)</code></p>

What type of Boolean logic circuit is this?

2010-02-28T02:45:18.017

1714

|stepper-motor|motor|driver|

<p>There are great constant current driver boards commercially available. But there is a limit to what voltage can accomplish in the ways of overcoming inductance. At some point motor selection becomes extremely important. I don't know your application but the lowest induction motor that satisfies your torque requirements is best for speed but this might mean a large motor case with a high inertia as it will use leverage from diameter or attraction over a long relutor to get torque instead of a strong electro magnet. If a small size motor like a nema 17 will do with torque you may be able to find them with a lower step count such as 100 or 64. A lower step count would help with speed. </p> <p>Check out www.mycncuk.com/1524-What-size-stepper-motor-do-i-need for calculations</p>

<ul> <li>How could I achieve this? </li> <li>What are the stepper motor facts and principless that I have to keep in mind to design a circuit to achive this goal? </li> <li>Are there any readymade/open source alternatives and circuits available to achieve this task? </li> <li>Do I have to approach design for geared and non-geared stepper motors?</li> </ul>

Is it possible to drive a stepper motor greater than 1000 rpm?

2010-03-01T10:19:06.683

1716

|microcontroller|arm|

<p>Not a Cortex-M3 but LPC2101 ARM7TDMI from NXP requires external 1,8V regulation.</p>

<p>Does anyone know of an ARM Cortex-M3 microcontroller with both the 3.3V peripheral and 1.8V core voltages supplied by external sources? Everything I have found so far has an internal regulator for the 1.8V CPU core. My problem is that I'm working in a high temperature environment and the internal regulators all have a thermal shutdown circuit to protect the chip which shuts the 1.8V off at 125C. I would like to supply the 1.8V with my own extended thermal protection that will run up to 200C but have not been able to find a microcontroller that will accept one.</p>

Is there a Cortex-M3 with external voltage regulators?

2010-03-01T17:13:12.710

1722

|arduino|programming|software|msp|

<p>For avr I normally program in assembler using a text editor. use avra or something like it to assemble and have my own simplified loader to load the programs into the device (command line).</p> <p><a href="http://www.dwelch.com/arduino" rel="nofollow">http://www.dwelch.com/arduino</a></p>

<p>Is the main way of programming the Arduino's Atmel MCU thru a Visual Programming environment such as Max/MSP? Or do you have to write typical C code?</p> <p>What are the different ways available?</p>

How do you develop software for the Arduino?

2010-03-02T16:33:39.190

1725

|power|

<p>This should work. You may have to change the values of the resistors, as adding another transistor affects the functioning of the circuit.</p> <p><a href="http://www.flickr.com/photos/b2gills/4404458667/" rel="nofollow noreferrer" title="Astable multivibrator relay by b2gills, on Flickr"><img src="https://farm5.static.flickr.com/4010/4404458667_2a39c7e64b_o.png" width="340" height="220" alt="Astable multivibrator relay" /></a></p> <p>I have actually used a similar circuit to operate a relay at about twice a second, at 12 volts. I plan on using it for a trailer wiring tester. </p>

<p>Hey I have a circuit like this, <img src="https://farm2.static.flickr.com/1137/758565223_c8c8119cdd.jpg" alt="alt text"></p> <p>I am powering this circuit with a 6v alkaline battery, the circuit works just fine with 100uf capacitors. But the problem is I want to replace the LED with a dpdt relay, I tried a 6v one I had laying around but it wont budge. Also when I tried the circuit with a 12v battery, the circuit just remains active for all the time. How do I get this to work?</p>

how to get more power out of a astable multivibrator?

2010-03-02T17:23:48.007

1738

|linux|pcb|

<p>I believe you are looking for something like the following <a href="http://hforsten.com/making-embedded-linux-computer.html" rel="nofollow noreferrer">http://hforsten.com/making-embedded-linux-computer.html</a></p>

<p>I'd like to make a single board computer capable of booting Linux, with my low-tech garage tools (2 sided PCBs, reflow skillet, no plating through holes).</p> <p>What's the simplest hardware design I could choose?</p> <p>Are there any microcontrollers with enough onboard flash/RAM to run Linux/uCLinux?</p>

What's the simplest Linux capable board I could make at home?

2010-03-04T23:37:36.143

1748

|stepper-motor|motor|driver|

<p>The Linistepper generates 6 microsteps in hardware, using the diodes and resistors to make the correct voltage levels for the 6 microsteps. This gives 200 x6 = 1200 steps/rotation which is one of the Linistepper microstep modes that you can select.</p> <p>To make 3600 steps/rotation the Linistepper alternates very fast in software between 2 of the microsteps. So it either does AAA or AAB or ABB (where A and B are 2 sequential microsteps) and at a high frequency around 333 kHz if you are using the 16MHz xtal. The overall effect is to provide 3600 microsteps from the 1200 hardware microsteps.</p> <p>Interesting note; the Linistepper is the only stepper driver that produces 3600 steps/rotation, making it ideal for things that work in degrees as it makes 10 microsteps per degree, also the smoothing caps C5 and C6 can be tuned (by choosing their value) to give very smooth transition from one microstep to the next when running at the "tuned" motor speed. Both those factors make it ideal for telescope movement (astronomy etc) and pan/tilt setups etc.</p>

<p>I have been trying to get the <a href="http://www.sxlist.com/techref/io/stepper/linistep/index.htm">Linistepper</a> to work, however I can't seem the understand the working of the circuit. </p> <p>The circuit is <a href="http://techref.massmind.org/images/member/RB-ezy-Q33/LiniV2_sch.gif">here</a>. </p> <p>The issues that I'm unclear about are: </p> <ol> <li>What are the diodes D1-D6 for? </li> <li>How does one calculate the resistors R18 - R23 for setting different microstepping current levels? (It is currently set to 0, 25, 55 ,100 % respectively). </li> <li>How does current regulation in the circuit work.</li> <li>PWM is used to achieve 3600 steps, how is this done? </li> </ol>

How does the Linistepper, open source linear Stepper Motor Drive work?

2010-03-05T14:12:14.260

1749

|schematics|software|design|

<p>In my eyes the best software is <a href="http://www.cadsoftusa.com/eagle-pcb-design-software/schaltplan-editor/" rel="nofollow">Cadsoft EAGLE</a>. Its the best schematic editor on the market. The new version V6 is easy to learn and easy to use. We also use it in university.</p>

<p>I'm sure there are plenty of schematic tools available. Which ones do you use/prefer?</p> <p>Feel free to also list tools which aren't completely free but very popular.</p>

What are the best free schematic tools out there?

2010-03-05T14:21:49.713

1760

|assembly|mips|

<p>This can be read in the 'debugging' help topic: "All data are stored in little-endian byte order (each word consists of byte 3 followed by byte 2 then 1 then 0). Note that each word can hold 4 characters of a string and those 4 characters will appear in the reverse order from that of the string literal."</p>

<p>I'm using the <a href="http://courses.missouristate.edu/KenVollmar/MARS/" rel="nofollow noreferrer">MARS simulator</a> to explore the MIPS cpu. I have a simple assembly program:</p> <pre><code>.data ascii1: .asciiz &quot;8C@2&quot; </code></pre> <p>I expect the value in the memory address for ascii1 to be 0x38434032 (the hex equivalent for the ascii bit pattern for &quot;8C@2&quot;). But it's not. Here's a screenshot of what MARS shows: <a href="http://img442.imageshack.us/i/mars1.jpg/" rel="nofollow noreferrer">http://img442.imageshack.us/i/mars1.jpg/</a></p> <p>Can someone explain why the value in 0x1001000 is not 0x38434032.</p>

MIPS: MARS editor not showing correct value for ASCII string?

2010-03-06T16:00:50.327

1770

|arduino|

<p>Take a look at this answer:</p> <p><a href="https://electronics.stackexchange.com/questions/4287/i-understand-arduino-now-what/4331#4331">I understand Arduino: now what?</a></p>

<p>I just got an arduino and have been working through some of the exercises in the tutorials, making good progress.</p> <p>When I'm learning a new programming language or tool, I usually work through a few steps: </p> <ol> <li>do the tutorials,</li> <li>modify the tutorial programs, get them to do new stuff, and</li> <li>solve a problem not covered in the how-to to make myself figure out how to do stuff.</li> </ol> <p>With Arduino, I have a bit of a chicken-and-egg problem. I don't have a good enough idea what I <em>can</em> do with it to come up with interesting problems to solve.</p> <p>What are some good problems/exercises I can tackle as a beginner to help myself learn more about what Arduino can do and how to do it?</p> <p>Problem statements only, please. Any instructions for solving them would defeat the purpose (though, it might make sense to point out what hardware is required.)</p>

Suggested exercises for learning with Arduino

2010-03-07T03:38:11.457

1781

|oscilloscope|probe|usb|

<p>You might also be interested in: <a href="http://www.fpga4fun.com/digitalscope.html" rel="nofollow">Digital Oscilloscope</a> at fpga4fun.</p>

<p>Idea:</p> <p>Take one oscilloscope probe, and one USB cable. Cut the BNC connector off the oscilloscope probe, and the USB B connector off the USB jack and splice them together.</p> <p>Mount all the USB &lt;--> analog circuitry inside the scope probe body and/or the USB A connector body. It would essentially compete with all the other USB oscilloscopes out there, but it would be in a single cable design - no extra boxes, etc.</p> <ol> <li>Is this a product you would like?</li> <li>What are your minimum specifications for this type of product?</li> <li>What are your ideal specifications for this type of product?</li> <li>Would this be any more useful or desirable than the current USB oscilloscopes available?</li> </ol> <p>My biggest concerns are:</p> <ul> <li>Obtaining the speed necessary to be reasonably useful without requiring a lot of components</li> <li>Synchronizing multiple probes into the computer (Getting nS accuracy without wiring the probes together seems problematic...)</li> <li>Fitting it all into the form factor and power limitations of a USB port (ideally 100mA unpowered hub ~0.5W)</li> <li>Keeping the assembled cost low</li> </ul> <p>I'd appreciate feedback on any or all of the above (what you want vs how to implement it). Ideally it'd be completely open source, but using very tiny surface mount parts it might not be easily assembled by hand.</p>

USB scope probe - request for comments and ideas

2010-03-08T15:23:18.807

1782

|pic|picaxe|microcontroller|

<p>The same MPLAB IDE can be used for all Microchip parts - 8-bit PIC10, PIC12, PIC16 and PIC18, 16-bit PIC24 and dsPIC, and 32-bit PIC32. It includes simulators and debuggers. Free development software that runs under MPLAB is available for all devices.</p>

<p>The impression I get is that PICAXE is based on the PIC cores, but geared to beginners, but I wanted to make sure before committing to any particular platform.</p>

What is the difference between PIC and PICAXE?

2010-03-08T15:48:37.223

1792

|pic|sensor|analog|temperature|

<p>You might also be running into EMI susceptibility. Active components (such as your PGA) are prone to a phenomenon called RF rectification where an AC disturbance at high frequencies at the input amplifier causes a DC disturbance at the output of an amplifier. This is very common in high-gain circuits (you'll see it a lot in thermocouple amplifiers) in an electrically noisy environment.</p> <p>If this is the problem, shunt out high-frequency noise by putting one or more good high-frequency bypass capacitors (1000pf-10000pf ceramic probably best) across the closest points that are inputs of your circuit. (for instance, if you have a 4-resistor one-op-amp differential amplifier:</p> <p><img src="https://upload.wikimedia.org/wikipedia/commons/thumb/d/d5/Opamp-differential.svg/200px-Opamp-differential.svg.png" alt="alt text"></p> <p>then put 2 capacitors at the input of the resistors -- from V1 to GND and V2 to GND, you may need a 3rd one from V1 to V2 if there is a lot of differential noise -- and NOT across the op-amp inputs)</p>

<p>I've had a number of issues getting good stable analog readings from an RTD temperature sensor. The temperature readings have a tendency to bounce as much as +/- 5 Deg C. The circuit is very basic, a voltage divider is formed between a fixed resistor and an RTD connected to ground. The voltage at the RTD is then fed into a programmable gain amplifier set at 16 V/V. The analog signal output from the programmable gain amplifier is then fed into a 10-bit ADC on a PIC microprocessor. I've implemented a low pass filter in software to attempt to fix the problem, but the temperature readings are still very unstable. Does anyone have any suggestions about where I could look to find the source of the problem and correct it?</p>

Reading RTD Temperature Sensor

2010-03-08T21:11:29.363

1807

|arduino|

<p>Maybe you could just get a bulk deal on these: <a href="http://www.freetronics.com/products/etherten" rel="nofollow">http://www.freetronics.com/products/etherten</a></p>

<p>I have build a prototype with the Arduino Duemilanove and a Ethernet shield. It works great, now I want to get it redesigned in to a single board with a few extra connectors. </p> <ul> <li>Screw terminal for power, </li> <li>Screw terminal for a few of the digital pins, </li> <li>RS232 connection to the serial port. </li> <li>RJ-45 port </li> <li>I also want an enclosure for this new board.</li> </ul> <p><strong>Q: Why do I want to redesign the board?</strong> I can't have a barrel connector for power, its a requirement from the site where I want to install this product. I also want a nice metal enclosure ( I couldn't find one for the Arduino that was reasonably priced. <p><strong>Q: How many units would you be making</strong> 100-250 to start and more as time goes on. </p> <p>My question is; Where should I post this job posting?</p>

Redesigning the Arduino Duemilanove and Ethernet shield in to a single board

2010-03-09T23:44:39.487

1808

|microcontroller|pic|programmer|

<p>I had to make the same decision a while ago when I broke my old PICKit2. Finally I decided to buy the PICKit2 again. Why? - it supports most Microchip devices -you can even program AVR MCUs with it see here <a href="http://pickit2.isgreat.org" rel="nofollow">http://pickit2.isgreat.org</a> -you can use the PICKit2 as a USB to serial converter (see link above) -has its own PC programming software and the pk2cmd command line tool (Linux support too) -PK3 is not mature yet</p> <p>Its not like buying a house.. if you dont like it, buy the other one.</p>

<p>Okay, having decided to pitch myself at the PIC family (including dsPIC), I now have a question about programmers. I've been hearing a lot of bad things about the new PICKit 3, and am wondering if I should get that or the apparently more venerable PICKit 2? If I want to be able to use the newest PICs, I think I might need to buy the latest, but I'm not so sure. Thank you!</p>

Should I get the PICKit 2 or 3?

2010-03-10T02:36:30.310

1815

|arduino|

<p>In fact, the layout files to (almost) all the Arduino boards are available on their respective pages, linked here: <a href="http://arduino.cc/en/Main/Hardware">http://arduino.cc/en/Main/Hardware</a></p> <p>I would recommend the updated version of the Arduino Single-Sided Serial board, described here: <a href="http://arduino.cc/en/Main/ArduinoBoardSerialSingleSided3">http://arduino.cc/en/Main/ArduinoBoardSerialSingleSided3</a></p>

<p>Where I live, one cannot buy an Arduino very cheaply. I figure, if I make one for my own purpose on a pcb then it would be much cheaper and would be much more fun. I cannot find any etchable PDF on the internet so can anyone point me to one?</p>

Arduino PCB etchable pdf

2010-03-10T14:58:47.947

1820

|soldering|soldering-iron-station|

<p>Yup, <a href="http://www.ebay.co.uk/itm/Soldering-Iron-Accessories-Kit-Set-Tools-Solder-Stand-Desolder-Braid-Wire-/141027512470" rel="nofollow noreferrer">it's a stand</a> - here's a photo of it assembled:</p> <p><img src="https://i.stack.imgur.com/jNagX.png" alt=""></p>

<p>This piece of metal was packaged with my new soldering iron.</p> <p><img src="https://i.stack.imgur.com/KofBd.jpg" alt="Mysterious piece of metal"></p> <p>Does anybody know what is it ? Is it a stand ?</p>

Mysterious piece of metal shipped with a soldering iron

2010-03-10T20:28:54.370

1827

|ethernet|pic|

<p>I have used the same chip from the same family (18F67J60) and I don't have quantitative data from its use, but your values are definitely significantly lower than I have seen (certainly my RX is many times faster than that).</p> <p>One application I use with the chip is do bootloading via TFTP and I can receive information on the PIC at ~20k/sec or so. I would look at how you're setting up your ethernet. Perhaps the registers are set up incorrectly? Is your ethernet hub bad? I would try importing one of the basic examples from microchip (its on the C: in the microchip folder and has a few example applications) and see how fast its going. Maybe use the Wireshark application to see the data going back and forth, maybe that will give you a clue as to whats happening.</p>

<p>Does anyone else use the PIC18F97J60 Ethernet capability? If so what kind of RX/TX performance is typical for that chip? I was running the TCPPerformanceRX/TX applications provided as part of the Microchip TCP/IP stack and getting between 1500-2000 bytes/sec TX and 60-80 bytes/sec RX. Receive seems way slower than it should be.</p>

PIC18F97J60 Ethernet performance

2010-03-11T15:03:29.577

1830

|microcontroller|pic|

<p>from the wikipedia page on <a href="http://en.wikipedia.org/wiki/Md5" rel="nofollow">MD5</a>:</p> <blockquote> <p>... it has been shown that MD5 is not collision resistant as such, MD5 is not suitable for applications like SSL certificates or digital signatures that rely on this property.</p> </blockquote> <p>and from the SSL researchers on the same page:</p> <blockquote> <p>We also hope that use of MD5 in other applications will be reconsidered as well.</p> </blockquote> <p>I understand that you probably don't want to hear this, but do you really need MD5? It shouldn't be used for cryptographic purposes as it is too insecure (and there are boatloads of rainbow tables available). If you are looking for something to just validate data, look into <a href="http://en.wikipedia.org/wiki/Cyclic_redundancy_check" rel="nofollow">CRC</a> (code <a href="http://www.netlib.org/crc/crc.c" rel="nofollow">here</a>) which is computationally cheaper. If you <em>are</em> using it for cryptographic purposes though, then may I suggest moving to <a href="http://en.wikipedia.org/wiki/SHA_hash_functions" rel="nofollow">SHA</a>? The only problem is that most cryptographically secure algorithms do not run particularly well on microcontrollers. I know it may seem like MD5 is "good enough", but the engineering way is to err on the side of caution.</p>

<p>Does anyone have any examples of the <a href="http://en.wikipedia.org/wiki/MD5">MD5 algorithm</a> for a microcontroller (preferably an 8-bit one)? Our project is going to use a Microchip PIC18 series device.</p>

MD5 implementation for microcontroller

2010-03-11T16:55:33.813

1842

|sensor|temperature|waterproof|

<p>This may be a bit pedantic, but (in the interest of not misleading newcomers) don't imply that thermistors are imprecise. I work with thermistors that are specified +/- 0.2 degC out of the box.</p>

<p>I'm looking into building a temperature monitoring system, and I want the sensor to have the ability to be submersed into boiling water. Can a thermocouple handle this? I'm looking into <a href="http://www.sparkfun.com/commerce/product_info.php?products_id=251" rel="nofollow">this</a> one now, but I'm not sure if it's waterproof.</p> <p>My other idea would be to drop a <a href="http://www.sparkfun.com/commerce/product_info.php?products_id=8227" rel="nofollow">small temperature sensor</a> into an aluminum tube and seal it off.</p> <p>Any ideas or suggestions?</p> <p><strong>EDIT:</strong> Sorry, I should have provided more context with my question. To clarify some things, the sensor will be used to monitor and control water temperatures ranging from 30F to 230F, not just to test when water is boiling :). Also, the water being monitored is consumable, so the sensor needs to be food safe as well, and since this is a hobby project, I'm trying to keep the sensor as cheap as possible.</p>

Waterproof Temperature Probe

2010-03-12T18:02:04.860

1847

|conformal-coating|potting|

<p>The wax, epoxy, and clay answers above might work, but if you want to have something tested with electronics, you want <a href="http://en.wikipedia.org/wiki/Potting_%28electronics%29" rel="nofollow">potting compound</a>. 3M Scotch-Weld DP270 (<a href="http://multimedia.3m.com/mws/mediawebserver?66666UuZjcFSLXTtnxfcOX46EVuQEcuZgVs6EVs6E666666--" rel="nofollow">datasheet</a>) and MG Chemicals' 832 series (different datasheets for color, strength, viscosity, hardness, etc.) are both popular examples. See the MG Chemicals appnote <a href="http://www.mgchemicals.com/downloads/appguide/appguide0405.pdf" rel="nofollow">here</a> [pdf] for a description of the potting and conformal coat processes.</p> <p><a href="http://en.wikipedia.org/wiki/Conformal_coating" rel="nofollow">Conformal coat</a> is <em>almost</em> what you want: It insulates, but it doesn't provide the structure you want. It's a very thin coating (Like paint, but it's usually clear) that provides a high dielectric between the components and the air. Techspray, Humiseal, Loctite, MG Chemicals, and Chemtronics all manufacture it. </p> <p>The other option is hot glue. Every stick I've used is nonconductive. Not sure how well it would work to make a ball, but it's worth a shot.</p>

<p>For example when you build a circuit you have the board and the components between them is air.</p> <p>Is there a clay like material that will act like air does?</p> <p>Application: you could bundle simple circuits into a ball, attach adhesive to the outside and throw them at things (LED throwie)</p>

Does this exist: Insulating material to cover circuit

2010-03-13T12:27:32.273

1848

|led|manufacturing|

<p>How many? For anything less than thousands it would probably be cheaper to solder a resistor to an LED and pot the whole assembly in acrylic</p>

<p>I would like to fab some custom LEDs Assemblies.</p> <p>Embed a resistor in the plastic, is there a smart way to go about doing this? </p> <p>I know Alibaba other than that nothing really.</p>

Custom LED Assembly manufacturing?

2010-03-13T12:48:28.623

1849

|resistors|i2c|pullup|

<p>According to the <a href="https://www.nxp.com/docs/en/user-guide/UM10204.pdf#G1660822" rel="nofollow noreferrer">I2C bus specification</a> The I2C pull up resistor value mainly depends on the I2C mode (Standard / Fast / Fast Plus / HS), VDD and the bus capacitive load.</p> <p>It's minimum value is calculated using the following equation:</p> <p><strong>Rpmin = (VDD – VOLmax) / IOL</strong></p> <p>Where:</p> <ul> <li>VDD: Power supply voltage</li> <li>VOLmax: Maximum LOW-level output voltage</li> <li>IOL: LOW-level output current</li> </ul> <p>While, it's maximum value is calculated using the following equation:</p> <p><strong>Rpmax = tr / 0.8473 x Cb</strong></p> <p>Where:</p> <ul> <li>tr: Maximum rise time of signal ( SDA / SCL / SDAH / SCLH)</li> <li>Cb: Maximum capacitive load for bus line</li> </ul> <p>I have built an online tool for sizing the pull up resistor at different bus modes. You can access it <a href="https://atman-iot.com/blog/i2c-pull-up-calculator/" rel="nofollow noreferrer">here</a>.</p>

<p><a href="http://ww1.microchip.com/downloads/en/DeviceDoc/21203P.pdf">The datasheet</a> of the 24LC256 EEPROM states that:</p> <blockquote> <p>The SDA bus requires a pull-up resistor to VCC (typical 10 kΩ for 100 kHz, 2 kΩ for 400 kHz and 1 MHz).</p> </blockquote> <p>I thought that any resistor with a kΩ value would do the job (and it seems that my EEPROM works fine at different frequencies with a 10 kΩ resistor).</p> <p>My questions are:</p> <ul> <li>is there a correct value for pull-up resistors ?</li> <li>is there a law/rule to determine this value ?</li> <li>how do different resistance values affect the I²C data bus ?</li> </ul>

Is there a correct resistance value for I2C pull-up resistors?

2010-03-13T13:36:33.733

1866

|i2c|

<p>I would recommend reading the datasheet again for that device. It sounds like CTRL0 and CTRL1 can also be used as output enables depending on the devices control registers MUX and BUS. This would explain why when you assert CTRL0/CTRL1 the oscillator output is disabled. Another thing to note is that the datasheet says the register values are store on an internal EEPROM, but only after a write command is executed. It could be possible that you think the registers are set one way, but when you power cycle the board the previous values are being loaded from EEPROM. I've worked a lot with I2C clock chips and every time things weren't working it was because I miss interpreted one of the register values. Write each register out on initialization then read them all back to make sure you initialized them properly. Compare the results to the datasheet to see if they make sense.</p> <p>EDIT: It appears that the CTRL pins can also be used to place the device in a power-down mode which would explain why it's not responding to I2C at times.</p>

<p>I'm trying to get the <a href="http://datasheets.maxim-ic.com/en/ds/DS1077.pdf" rel="nofollow" title="DS1077 datasheet">DS1077</a> to work, but I can't for the life of me figure out what I'm doing wrong. I'm using the defaults for the MUX and BUS registers, and programming in my own DIV frequency has no effect. I can read out the registers over I2C and they return the values I set, but the oscillator output (as measured on my scope) is nothing like what it should be. I tried copying the values in from <a href="http://www.sparkfun.com/datasheets/BreakoutBoards/DS1077v2.c" rel="nofollow" title="C code">SparkFun's example</a> (I'm using their breakout board) but the "40kHz" output is way above the 60MHz bandwidth of my scope.</p> <p>I found an <a href="http://www.maxim-ic.com/app-notes/index.mvp/id/171" rel="nofollow">example on Maxim's website</a> and they recommend you tie CTRL0 and CTRL1 to GND if you're not using them - but if I tie CTRL1 to GND mine stops responding to I2C messages! I have to tie CTRL1 to VCC to get it to respond over I2C (no mention of that in the datasheet), but that disables the oscillator output. Otherwise my "circuit" is the same as their example - SDA/SCL go to an Arduino, and the OUT pins go to my scope. VCC and GND are connected correctly and within spec.</p> <p>I've got no idea what's going on, it seems really simple but I still can't get it to work :'-( Has anyone encountered anything like this before? Any ideas to help narrow down the problem?</p>

Can't get DS1077 programmable oscillator to work

2010-03-14T08:29:58.940

1869

|capacitor|impedance|inductive|inductance|gyrator|

<p>Simply increasing passive capacitance can only cause the current phase angle to asymptotically approach the limit of leading by 90 degrees. However, in op-amp circuits they can be used to eliminate inductors, but this has more to do with the topology of the feedback circuit than any innate ability to shift phase.</p>

<p>so if you add enough caps can you emulate what an inductor is doing, ie. Lead the current so far that it appears to be lagging? </p> <p>I assume this doesn't work, why not?</p>

Theory: With an AC circuit adding capacitors will cause the current trend towards leading

2010-03-14T19:36:57.303

1870

|integrated-circuit|

<p>Old thread, but I found this IC socket that should fit. I have this chip also and it doesn't fit a breadboard, hopefully the socket will allow a little more space to fit it. <a href="http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail&amp;itemSeq=148241958&amp;uq=635331715231561752" rel="nofollow">http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail&amp;itemSeq=148241958&amp;uq=635331715231561752</a></p>

<p>I got this chip and didn't realize the pins were not the normal spacing.</p> <p><img src="https://i.stack.imgur.com/40L3M.jpg"></p> <p>Anybody know where to find a header for it.</p> <p>BTW the chip is a re-issue of the old sound chip SN76477</p> <p><img src="https://i.stack.imgur.com/dxZuV.png"></p>

Where can I fnd a header for this goofy chip

2010-03-14T20:38:49.153

1873

|atmega|simulation|ide|sata|

<p>Wow, I would've expected the 133MHz ATA/IDE interface would be too fast for an ATmega chip, but it looks like they use it in ATA33 (33MHz) mode, somehow getting it to work with a 4MHz(!) ATmega32.</p> <p>In this case you shouldn't have any problems with a SATA to IDE converter, since they're designed to support older ATA33 devices.</p> <p>Note however that the OS SCSI stack is only used for SATA devices. IDE uses a different command set, so you won't see SCSI commands arriving at your ATmega, if that's your intention. (The host PC will certainly issue SCSI commands though, and the SATA to IDE device will translate.)</p> <p>An alternative that might be easier to achieve is to use a USB interface chip to make your ATmega appear as a USB hard drive. AFAIK this <em>does</em> use the SCSI protocol (perhaps a limited subset of it though), so you would see SCSI commands arriving on your device. Recent PCs can boot off a USB hard drive too, if that's your need for connecting directly to SATA.</p> <p>This solution would be much less sensitive to timing too, as the USB chip would talk over the USB bus at the correct speeds, allowing you to talk to the chip at whatever speed you can manage.</p>

<p>I'm going to start a new project and I wonder if the concept makes sense. (I'm not so familiar with ATA specifications to answer this by myself :))</p> <p>The concept:</p> <p><b>HW design:</b></p> <p>"SATA connector on motherboard" &lt;-> "SATA cable" &lt;-> "SATA/IDE HW converter" &lt;-> "ATMEGA168"</p> <ul> <li><p>"SATA connector on motherboard" &lt;-> "SATA cable" - Device would be connected to SATA port on PC motherboard with typical SATA cable</p></li> <li><p>"SATA/IDE HW converter" - on my PCB I will use one of SATA/IDE controllers, so far I've found: JMicron - JM20330,<br> Atmel - AT78C5010,<br> ACARD - ARC-770</p></li> <li><p>"ATMEGA168" - as programmable unit I'd like to use ATmega168 (or any other cheap 8-bit microcontroller)</p></li> </ul> <p><b>Purpose</b></p> <p>With this device I'd like to simulate presence of hard drive in a system. As I want SATA/SCSI stack to be used by OS I need to use SATA ports on motherboard. AFAIK connecting to SATA interface without SATA/IDE converter is impossible with ATMega microcontrollers due to big speed of SATA bus interface. Nevertheless I've found IDE/ATA implementation for 8-bit uC: <a href="http://www.opend.co.za/hardware/avride/avride.htm" rel="nofollow">http://www.opend.co.za/hardware/avride/avride.htm</a></p> <p><b>Wonders</b></p> <p>My biggest concern is the SATA/IDE converter, I wonder if it can be easly used with micro-controllers as ATMega?</p>

Simulate HDD using ATMega168

2010-03-14T21:12:19.607

1885

|temperature|sensor|wireless|

<p><em><strong>DISCLAIMER</em></strong> I do work for that Yoctopuce company which designed the product described here, so that answer might not feel as altruist as you would like it to be. </p> <p>You might want to have a look at Yocto-Temperature and YoctoHub-Wireless from Yoctopuce. The Yocto-temperature is a just regular USB temperature sensor as you can find many on the internet, but it can be plugged on a YoctoHub-Wireless from the same company. That hub is a WiFi transmitter which can control any Yoctopuce device. You will then have direct WiFi access to your sensor. You can also ask the hub to automatically report sensors data on a server of your choice (much easier to go through NAT filters that way).</p> <p><em><strong>Ease of use</em></strong></p> <p>Plug, configure, program your application and play. But you will have to work on the enclosures, especially if you want to put it outdoors as I suspect. </p> <p><em><strong>Electrical consumption</em></strong></p> <p>WiFi is a power greedy technology. Actually a YoctoHub-wireless + one sensor consumption is about 140mA. But the hub features a deep sleep mode. In that mode the hub wakes up from time to time, post sensors data, and goes back to sleep. Consumption in deep sleep more is less than 15 uA. Then, depending on how you configure it, the installation can hold on batteries for weeks... or months.</p> <p><em><strong>Price</em></strong></p> <p>More than $50, I'm afraid. But I seriously doubt you can find a reliable WiFi temperature sensor for less than $50. Note that if you use a cheaper technology, you will have to buy a bridge between that technology and your network. Moreover, if you really think that more than $50 is a deal breaker, you should ask yourself how much you would like to be paid to provide what you're asking for. And don't forget: that money is supposed to pay for raw components and to feed you as well :-) </p> <p><em><strong>Application</em></strong></p> <p>Here is a application example involving a YoctoHub-Wireless and an Yocto-Meteo which is just an improved Yocto-Temperature. Basically it's an outdoor solar-powered, wifi, temperature/humidity/atmospheric pressure sensors array. It is powered by one of these USB solar chargers. <a href="http://www.yoctopuce.com/EN/article/an-autonomous-solar-weather-station" rel="nofollow">http://www.yoctopuce.com/EN/article/an-autonomous-solar-weather-station</a></p> <p><em><strong>Alternatives</em></strong></p> <p>Here are some other WiFi alternatives, which I believe are as good as the Yoctopuce one, minus the power issue handling.</p> <ol> <li><p>DIY Hardcore: Arduino + wifi shield + temperature sensor such as <a href="http://www.sparkfun.com/categories/82" rel="nofollow">http://www.sparkfun.com/categories/82</a></p></li> <li><p>DIY casual: Raspberry PI + USB wifi dongle + usb temperature sensor . Note that USB temperature sensors are very common: <a href="http://www.phidgets.com/products.php?category=35" rel="nofollow">http://www.phidgets.com/products.php?category=35</a> <a href="http://www.raphnet.net/electronique/usbtenki/index_en.php" rel="nofollow">http://www.raphnet.net/electronique/usbtenki/index_en.php</a></p></li> <li><p>Ready to use: Temper@tureAlert have a whole range of ready to use temperature sensors, including wifi version <a href="http://www.temperaturealert.com/Temperature-Alarm.aspx" rel="nofollow">http://www.temperaturealert.com/Temperature-Alarm.aspx</a> </p></li> </ol> <p><em><strong>As a conclusion</em></strong></p> <p>The hardware is just the visible part of the iceberg. Whatever solution you choose, make sure you choose one with a decent API, or it will be useless.</p>

<p>Are there any low-cost (&lt;50$USD) wireless ambient temperature sensors available?</p> <p>I would like a simple to interface to the sensor i.e. IP over Wifi if at all possible.</p>

wireless temperature sensor

2010-03-15T13:56:16.457

1886

|current|cmos|energy|theory|

<p>If you <a href="http://www.sciencedaily.com/releases/2006/02/060223084147.htm" rel="nofollow">don't have to run the program to get the result</a>, that would seem like a step in the direction of computing something for nothing, though their apparatus must have been dissipating some power.</p>

<p>CMOS greatly reduces the current draw of ICs because one of the complementary FETs is always in the non-conducting mode, so there is only a flow of current during the transition between states, which is just the amount of charge on the gate's equivalent capacitance and maybe some leakage when both gates are open momentarily. </p> <p>Is it theoretically possible to make a logic gate that has zero leakage while changing states (using any realistic technology), and the signal is just passed through the circuit as changes in voltage causing other changes in voltage? If not, what's the theoretical minimum?</p>

In theory, is it possible to make a logic gate that uses zero current?

2010-03-15T16:45:52.723

1887

|stepper-motor|h-bridge|mbed|

<p>To make that kind of stepper rotate, you need to produce what amounts to a two-phase (90deg apart) system of currents in the windings.</p> <p>If your stepper has legs labeled A and B for one winding, and C and D for the other, you'd want to cycle through the following pattern of currents</p> <pre><code>+A -B and +C -D .. where +A -B means current into A, returned on B, etc. +A -B and -C +D -A +B and -C +D -A +B and +C -D </code></pre> <p>Each cycle through those four states will take the motor through one <em>electrical</em> revolution. Steppers usually have a large number of poles, so it will take some number of cycles before you get one complete mechanical revolution of the motor's shaft.</p> <p>Now you have two H-bridges, one for the AB winding, the other for the CD winding. This is four controller bits per winding, eight in all. (It would not be premature to optimize this down to four bits right away, but I'm going to skip doing that for just a moment)</p> <p>Referring to the high-side drive for leg A as AH, and the low side as AL, and so on, you can produce the above sequence of currents by turning on the drive transistors this way</p> <pre><code>AH AL BH BL CH CL DH DL 1 0 0 1 1 0 0 1 1 0 0 1 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 1 0 0 1 </code></pre> <p>By now it should be obvious that the H and L controls for a given half-bridge are always the negation of one another. In fact, if you ever drive the high and low sides of the same half-bridge on, you'll smoke the bridge, so it's safer to output just the one control bit per half-bridge, and use a hardware inverter to get the complementary control. </p> <p>You should also notice that the sequence never turns on both high-side drives (or both low-side ones) for a given winding. The B drive is the complement of the A drive. So you could in fact get this down to a mere two bits.</p> <p>I think if I had to drive this kind of a motor from a micro-controller, I might use a 7474 dual D flip-flop (D-FF) as a kind of external 2-bit register with dual rail outputs. Each data input of the 7474 would be hooked to its own micro output bit. A third bit from the micro would drive the clock. Then, Q1 would drive AH and BL, Q1* drives AL and BH, and similarly, Q2 feeds CH and DL, while Q2* goes to CL and DH. Each FF bit effectively sets the direction of the current in one of the windings.</p> <p>Then, in software, you just output the two bits to set the current directions the way you want, and clock them into the FF by driving its clock low and then high again. Then your two-phase motor sequence is</p> <pre><code>clk AB CD 0 1 0 ; be sure to get D-FF inputs ready with the 0 state of the clock 1 1 0 ; b/c the 7474 will latch the values on the positive edge. 0 0 0 ; you want the data lines stable during the clock edge. 1 0 0 0 0 1 1 0 1 0 1 1 1 1 1 </code></pre> <p>So, at a cost of three bits, you can step the motor, although there's always a current through both coils, so you can't free-wheel the motor.. unless you use a 4th bit to act as a global enable for both sides of both bridges.</p>

<p>There is some information on chiphacker about using an arduino to control stepper motors (I'm driving Bipolar, 4 wire, motors), however I'm finding it hard to know how to control a stepper motor using my <a href="http://mbed.org" rel="nofollow noreferrer">mbed device</a>.</p> <p>The fact that I'm using an mbed is really by-the-by, I've rigged up an H-Bridge so that I have 4 pinouts of my microcontroller/microprocessor going to the required pins of the H-Bridge What pulses should I send to which of the pins when? I can PwmOut if thats more useful. Like this:</p> <p><img src="https://i.stack.imgur.com/Ryq5k.jpg" alt="connections"></p> <p>Any advice would be very welcome, even if its just a URL to a reasonably detailed tutorial. </p>

Stepper Motors (on mbed, not arduino)

2010-03-15T17:29:47.520

1888

|mbed|programmer|

<p><a href="https://www.xmos.com/products/development-kits/led-reference-design-kit" rel="nofollow">XMOS chips</a> are used for driving large LED arrays. They are used in conjunction with Macroblock shift registers.</p>

<p><em>For those of you that haven't heard of the <a href="http://mbed.org" rel="nofollow">mbed</a> I'd highly recommend having a look at it for rapid prototyping!</em></p> <p>So, the mbed is a 100MHz microprocessor that appears as a usb mass storage device when you plug it into a computer via USB. You can program it by using an online IDE which spits out compiled binary files you can drag-drop into the drive (on any OS) making it a very versatile and very easy to use tool for beginners (like myself!)</p> <p>As with all of these programmable ICs they have a limited number of IO pins, so if you wanted to drive 150 LEDs individually you'd need to have some kind of intermediatry control device. I'm considering using ATtiny devices to do just that:</p> <ol> <li>Is using ATtiny devices a good way to achieve control over a large number of LEDs? (considering my lack of experience with hardware)</li> <li>Would it be hard to port the code from the arduino ISP so that I could use my mbed as a programmer for programming ATtiny?</li> <li>Am I better off using PIC chips?</li> </ol> <p>Many thanks!</p>

mbed as a programmer

2010-03-15T17:38:26.157

1904

|pcb|soldering|flux|

<p>Solder fumes can have halides in them. The flux containes halides which means bromine and chlorine for most fluxes. These ions are not good to breathe in. With most fluxes you can check the content of the flux in it's corresponding datasheet if it's available.</p>

<p>I do a fair bit of soldering (lead-free). Is breathing in solder/flux/paste fumes actually going to harm me?</p> <p>Are cheap fume extractors worth buying?</p>

Are solder fumes bad for me?

2010-03-15T22:13:03.210

1911

|assembly|microprocessor|

<p>Many processors are driven by a state machine whose transition sequence is affected by the instructions being executed. Microcode "instructions" often specify the interactions among various registers and buses in a way which would not be visible to a programmer.</p> <p>For example, a microcode instruction for an 8-bit CPU in state #1 might specify that output enables for both halves of the program counter should be active (causing the program counter to be output on the upper and lower internal address bus), the program-counter-increment signal should be active, the external address latch signals should be active (so the external address bus will track the internal one) and the RAM-read signal should be active, and the controller should switch to state #2.</p> <p>In state #2, the external data bus should feed to the internal primary data bus, and the instruction register, which reads from that bus, should be loaded. The program counter should as before be output on both halves of the address bus, and another RAM-read issued. Bits 5-7 of the instruction register should be loaded into bits 0-2 of the state controller, bit 3 of the state register should be set unless bits 1-7 of the instruction register are all set, and other bits of the state register should be clear, the net result being that the next state will be #7-#15.</p> <p>Note that microcode isn't really defined in terms of instructions, but rather in terms of combinations of control signals. The hardware will not be set up to allow general-purpose instructions in microcode, but rather to load or output various registers from/to the buses on which they sit, or connect different buses to each other, and use various bits or combinations thereof to select different states. Many aspects of the design will be hard-wired (e.g. opcodes FE and FF might be special-cased in hardware rather than in microcode). The idea with microcode isn't to run programs, but to replace logic.</p>

<p>I'm a bit confused between the microprogramming level vs machine language level. For example:</p> <ol> <li>Where do both types of programs reside while being executed?</li> <li>Do either have a 1:1 mapping to assembly language true-op instructions?</li> <li>Is the format of either defined by the processor architecture?</li> </ol>

Microprogramming vs. Machine Language programming

2010-03-16T01:51:31.173

1920

|arduino|avr|encryption|reverse-engineering|

<p>If it's that important and you're particularly worried about competitors stealing your code, take out IP protection on your code segments. You should be looking into this if you're going to try and make money out of a project anyway.</p> <p>Certain elements of code can be either patented (for specific processing methods and novel algorithms) or registered as industrial designs (the look, layout and application of your code to a device). You may wish to consult an IP lawyer on this.</p>

<ol> <li>What is the best way to protect code flashed onto any AVR based device from reverse engineering? </li> <li>What is an easy way to provide updates to end users to flash on their own without disclosing the code? (Is it with a bootloader that decrypts an encrypted image?)</li> </ol> <p>Don't flame me for promoting DRM, I am in favor of open platforms--I am just curious how this would work.</p>

Securing code on an AVR/Arduino and delivering updates

2010-03-17T02:37:20.043

1935

|led|sensor|adc|hall-effect|

<p>If you want to do this with just a single LED you could just use a simple comparitor to generate a PWM signal to power the LED. Connect the positive lead of the comparitor to the output of your hall effect sensor and the other lead to a RC triangle wave generator. </p> <p>For a good example of this type of circuit see <a href="http://www.solarbotics.net/library/circuits/bot_ornament_qlf.html" rel="nofollow">http://www.solarbotics.net/library/circuits/bot_ornament_qlf.html</a>. Just replace the connection to the lower frequency oscillator to your hall effect IC and you will have a PWM LED fader with 0 digital electronics!</p>

<p>I have a hall effect sensor which outputs 0V when on the North pole of a magnet, 5V when on the South pole. It idles at 2.5V.</p> <p>I want to connect 2 LEDs to show the reading, one activated from 0-2.5V, the other from 2.5V to 5V.</p> <p>I could use the ADC on a microcontroller to read the sensor then drive the LEDs with two PWM channels. But, this seems like overkill to me.</p> <p>Can anyone suggest a better way? Without using a microcontroller?</p>

How to convert a voltage range to LED brightness without a microcontroller?

2010-03-18T22:08:57.397

1942

|usb|interface|

<p>The <a href="https://blog.petrockblock.com/gamepadblock/" rel="nofollow noreferrer">GamepadBlock</a> makes use of an ATmega32U2 together with <a href="http://www.fourwalledcubicle.com/LUFA.php" rel="nofollow noreferrer">LUFA</a> to implement a full speed USB HID device to poll several original game controllers. The ATmega has a hardware USB interface and getting started was easy since LUFA provides several demo projects.</p>

<p>How does one go about building an interface for a USB device that allows interfacing pots, linear/log tapers, and momentary/toggle switches to a computer?</p> <p>If someone could give me a high-level description, I would appreciate it. I can read spec sheets, so understanding details is not a problem as long as I know where to find the sheets.</p>

How to build a USB controller having knobs, sliders, and switches

2010-03-19T04:11:00.617

1949

|lcd|display|

<p>Hmmm. I'll assume that you mean an LED display.</p> <p>If you are wanting to display a full character set, you might want to consider using several 5x7 led matrix. See <a href="http://www.best-microcontroller-projects.com/led-dot-matrix-display.html" rel="nofollow">http://www.best-microcontroller-projects.com/led-dot-matrix-display.html</a> for an introduction. MAX7221 driver chips can be used to instead of multiplexing the rows and columns. While the extra chip does add to the parts costs, it will mean bright letters and less pins being used.</p> <p>Give the dimension of the display that you are after, you'd need to find a LED matrix which contains 10mm LEDs.</p> <p>I don't see this as a cheap project by the time you assemble the LED matrix displays. Good luck as it sounds like fun.</p>

<p>I'm looking around for a large LCD character display (metre-ish long, 10-15cm high), and on the cheap side (of course)</p> <p>Any suggestions?</p> <p>Actually I think I meant LED display, max $150ish</p>

Source a really big LCD character display

2010-03-20T11:57:33.850

1961

|frequency|

<p>One approach would be to use a voltage controlled oscillator (VCO) and a ramp generating circuit.</p> <p>The CD4046 has a VCO block in it or there are some function generator ics, like the MAX038. You'll need to find something that covers that range of frequency you need. To produce a ramp, it could be as simple as a capacitor pulled up (or down) to the input of the VCO.</p> <p>If you need a linear ramp, then driving the capacitor with a current source would be more suitable.</p>

<p>I am wanting to design a circuit that uses an astable multivibrator as a clock source. However the difference being that over time the clock is gradually sped up until it reaches some multiple frequency.</p> <p>I have found circuits that have a speed that that decreases to zero (an addition of a cap) but not one that speeds up.</p> <p>Any ideas or help to point me in the right direction would be great! Thanks jme</p>

Astable multivibrator with increasing frequency

2010-03-22T08:46:29.090

1964

|radio|amplifier|theory|electromagnetism|

<p>There seems to be this fixation on how fast electrons or signals move in wire. That does represent a fundamental lower limit on propagation delay thru a amplifier, but that is swamped by other delays in most amplifiers. The individual active components of the amplifier will have a greater delay, and then there will be delay associated with the bandwidth of the amplifier. Usually there are deliberate bandwidth limiters in the path that represent the largest input to output delay.</p> <p>The reason for the deliberate bandwidth limiters is to make it predictable. Individual transistors or other active devices can vary significantly. Device are chosen to still operate well up to the intended upper frequency or bandwidth. The bandwidth or frequency limiters then guarantee that the active devices are only presented with frequencies they can handle. If you give them frequencies outside that range, all kinds of undesirable non-linear effects can occur.</p> <p>A radio transmitter in particular has very carefully tuned and usually sharp cutoff bandwidth limiting on its modulated signal. There are practical reasons for this, but also legal reasons. The spectrum of a transmitted signal depends in part on the bandwidth of the modulation signal, and there are legal requirements as to how wide that bandwith may be. If the modulated signal weren't bandwidth limited in the transmitter, then the radiated signal would spill from the assigned band to a band assigned to another station, which of course is not allowed.</p> <p>So the signal path from the input of a radio transmitter to the broadcasted signal always has some delay for various reasons.</p>

<p>I'm having an argument with a classmate and we can't agree.</p> <p>He tells me that it's not possible for the amplifier of a radio station to amplify the input signal "instantaneously" (at the speed of light), because they work with very big powers (tens of kilowatts) and you can't accelerate the electrons that quickly.</p> <p>I insist that since it's an analog device, it will work at speed of light, and that you don't need to accelerate the individual electrons, but only the electric/magnetic fields.</p> <p>So which one of us is right in this particular case? Is there a delay in amplifying a signal for a high powered radio station? The radio station part is important. He agrees for example that a typical home audio amplifier is instantaneously.</p> <p>It would be great if you could provide a reference link for an answer (if possible). Wikipedia would be fine. But don't waste your time searching for one.</p>

Does a radio station main amplifier work at the speed of light?

2010-03-22T15:30:29.053

1968

|audio|electromagnetism|

<p>See this link for details on using a moving string as a pickup. <a href="http://music-electronics-forum.com/t14952-2/" rel="nofollow">http://music-electronics-forum.com/t14952-2/</a></p> <p>The most practicle way is to use an 8 ohm to 20K ohm or higher miniature transformer (8 ohm side) attached across a string behind the nut and the bridge. The string acts like the ribbon in a ribbon microphone. </p> <p>Attach the high impedance side of the transformer to the amp input. Also, attach one leg of the low impedance side to the high impedance ground side to minimize noise. </p> <p>Place one or more magnets in the space between the neck and the bridge and listen for tonal changes as the magnet position is changed.</p> <p>You can also pass a string or strings through miniatute toroid current transformers to obtain sound from each independent string or the combined strings. </p> <p>Transformers are the most practicle way to boost the very low impedance of a guitar string in the .5 to 1 ohm range up to a higher more useable level without introducing too much noise.</p> <p>The sound quality with this setup can be more acoustic sounding than the traditional sound of a high impedance guitar pickup that all have a resonant hump in the 2Khz to 5Khz range.</p>

<p>The normal musical instrument pickup uses a magnet inside a coil, and the movement of a ferromagnetic string causes changes in the magnetic field, which then induce currents in the coil.</p> <p>Another possibility would be to use just a strong magnet near a string, and measuring induced currents in the string itself. This would only require a conductive string, not a ferromagnetic one.</p> <p>Does anyone actually use this method? Is there a name for it, or is it useless, so no one talks about it? I tried it last night, and it works, but the signal is very low (-50 dBV, for instance, vs -5 dBV for a magnetic electric guitar pickup).</p>

Amplifying instruments by measuring current in conductive strings

2010-03-22T16:27:39.187

1980

|soldering|temperature|

<p>I set my iron to 800F and never touch it again. I use a big chisel chip for large parts and small fine tip for through hole parts. </p> <p>The main problem you will run into with too much heat is the pad delaminating from the board. This is more of a problem when desoldering than soldering. That's why its important to be quick and not hold the iron on the board for too long. Using a hotter temperature for a shorter period of time is the way to go. </p> <p>Some other tricks to help are to use flux core solder and add flux as necessary. Adding a little bit of solder to the iron tip helps conduct the heat from the tip to the part/pad also. </p>

<p>I recently purchased a Weller WES51 soldering iron as my first temperature controlled iron and I'm looking for recommendations on the best default temperature to use when soldering.</p> <p>I'm using mainly .031 inch 60/40 solder on through-hole components.</p>

What’s the proper soldering iron temperature for standard .031" 60/40 solder?

2010-03-22T23:13:59.587

1983

|led|pwm|

<p>If the goal is only a smooth brightness level ramp-up through the full-range of possible brightness levels:</p> <p>The time step linearly decreasing as the brightness increases with a constant step, results in the brightness level exponentially increasing in time.</p> <p>Example:</p> <pre><code>#define MAX_DUTY 255 #define MIN_DUTY 0 #define RAMP_DOWN 0 #define RAMP_UP 1 #define MIN_DELAY 100UL #define MAX_DELAY 1000UL void loop(void) { uint32_t delay; uint8_t duty; int8_t ramp_dir; duty = MIN_DUTY; ramp_dir = RAMP_UP; for (;;) { // Offset by +1 to avoid division by zero for (delay = MIN_DELAY + ((MAX_DELAY - MIN_DELAY) * (MAX_DUTY + 1)) / (duty + 1); delay &gt; 0; delay--) { ; // Wait } if (ramp_dir) { if (duty &lt; MAX_DUTY) { duty++; } else { duty--; ramp_dir = RAMP_DOWN; } } else { if (duty &gt; MIN_DUTY) { duty--; } else { duty++; ramp_dir = RAMP_UP; } } set_led_duty(duty); } } <span class="math-container">```</span> </code></pre>

<p>When driving an LED with PWM, the brightness (as I perceive it) does not scale linearly with duty cycle. The brightness is slow to ramp up, then increases exponentially with duty cycle.</p> <p>Can anyone suggest a rule of thumb to use as a correction factor, or other workaround?</p>

Correcting for non-linear brightness in LEDs when using PWM

2010-03-22T23:43:16.537

1984

|led|rgb|colour|

<p>Well, the easy method would be to find a friend who can see colors and ask him to pick 16 colors for you. </p> <p>The first 8 colors (7 if you don't count black) are easy...just run through all the possible combinations of on/off LEDs. To get more than that, you'll need to vary the brightness of the individual colors. Generally you vary LED brightness not via voltage, but via PWM (very quickly turning the LED on and off. Spending more time off to make it appear dimemr)</p>

<p>I have some RGB LEDs (eBay - no datasheet, 4 pin, common cathode, 5mm). I am colourblind.</p> <p>I'd like to create a palette of colours which appear distinctly for most people's eyes, perhaps 16 colours or more. How could I generate this palette?</p> <p>I guess that the colour produced will be far from a perfect match to the duty cycle applied.</p> <p>The human eye is apparently more sensitive to green, could I use this (and other factors) to improve the colour output?</p>

Colour correcting RGB LEDs - possibly with science

2010-03-23T00:08:51.650

2000

|video|display|

<p>For OSD solution, an FPGA-based approach could be an alternative. </p> <ul> <li>OSD can be achieved with an alpha-blending implementation.</li> </ul> <p>The alpha-blending is an algorithm for mixing 2 images into one. The good point is that this gives you the possibility to configure the level of transparency of individual picture elements.</p> <p>In few words: being x and y the inputs and z the output video signal. An alpha-blender circuit can mix them implementing the equation:</p> <p>z = x.(alpha) + y (1-alpha)</p> <p>alpha is the coefficient or level of blending. Then you can define "x" as the NTSC video and "y" as the overlay.</p> <ul> <li>Additionally, an FPGA could match your needs in case you may consider additional logic as the video encoder/decoder you mentioned. Everything (enc/dec and their required memory interfaces and the OSD) could fit on a single FPGA (if big enough).</li> </ul>

<p>I want to take a NTSC/PAL component video and overlay graphics over it.<br> I am aware of solutions that either use the max7456 overlay chip, or accomplish it <a href="http://www.viennawireless.org/Balloon/hardware/overlay/index.php" rel="nofollow">with just an AVR</a> but these seem to have limited resolution and are monochromatic. Ideally I would like to have something comparable to the performance of <a href="http://www.diydrones.com/video/hud-test-on-a-trex-500?xg_source=activity" rel="nofollow">this setup</a>.</p> <p>Here is what I know I will need:</p> <ul> <li>Video decoder (to digitize NTSC/PAL)</li> <li>Some sort of buffer/processor to overlay graphics onto the digitized frame</li> <li>Video Encoder (to re-encode to NTSC/PAL)</li> </ul> <p>The middle part is what I am not sure how to setup. Are there existing chips that will automatically do this overlaying for me somehow, or do I just need a sufficiently powerful MCU and RAM to buffer/manually manipulate a bitmap? Ideally I would like to have something low cost, and preferably a single chip solution.</p>

Video overlay / on screen display architecture

2010-03-23T18:30:30.107

2012

|avr|atmega|books|c|

<p>You can start off from C programming for microcontrollers by Joe Pardue. Use AVRStudio5 and stick to <a href="http://avrfreaks.net" rel="nofollow">http://avrfreaks.net</a> ,you can get a lot of cool and helpful guys here.</p>

<p>I have a ATmega32 board laying around and I figure it would be perfect to start off with microcontrollers. I once did some babbling in embedded C (thats when I got this board) but the flow was stopped due to some things. Now I have two questions:</p> <ol> <li><p>What is the best free resource to start off with C for the avr series. I know of AVR-GCC but was looking for some tutorials or free books to start me off.</p></li> <li><p>Should I directly jump to C or go through ASM first? I see there are many asm books around. So what is a better option?</p></li> </ol> <p>While searching the Internet, I found the Arduino bootloader for ATmega32 here <a href="http://retrointerfacing.com/?p=30" rel="nofollow">http://retrointerfacing.com/?p=30</a> but the problem is I a hesitant to do some tinkering with the fuse bits and all. Is it safe to do so? </p>

Start off with embedded C with ATmega32 (ATmega AVR series)

2010-03-24T05:22:27.930

2021

|bias|resistors|

<h1>Summary</h1> <p>If the driving stage output is of 'relatively low' impedance (and is thus more of a voltage source in actuality) the series resistor must be present to convert it to a current source, just like in any other case of driving a diode or generalized low-impedance target. Quite often for instance, current is set through an LED to meet its specifications in exactly this way.</p> <hr /> <p>Whatever source or sink of current (output) is driving the transistor (an open collector / level shifter, a CMOS output, what have you) is ultimately to be driving such current to a silicon diode (or two in the Darlington case), for all it knows of the base-emitter junction(s) of the transistor(s) in question. Speaking of which [plural case], when power transistors are to be paralleled, it may be more important to degenerate their emitters to prevent fallen hero syndrome, a.k.a. thermal runaway.</p> <p>Barring excessive resistance values and low current gains, it has little do with current gain, as any such design case would fundamentally tend to include transistor saturation on the real-time operational menu (i.e., using as a switch or other high-gain or logic-drive scenario rather than a linear amplifier) and the principal pitfall would be excessive resistance which could choke the transistor at an unreliable threshold, short of saturation (generally non-applicable in Darlington case), and this would be load-dependent (as a consequence of hFE), probably thermally adverse, and not CMOS-input-compliant. Analog or mixed (ADC) detection could probably make sense of it though, but now I'm headed out on a tangent based on random and frivolous guesses about your application.</p> <p>The series resistance can also provide a certain meaning to Miller capacitance (collector-base) in the same way (or reveal the parasitic Miller cap) via the impedance increase, which could be good or bad but sort of brings linear amplification into the realm of inclusion of a series base resistor, particularly where interstage/open-loop gains are high and a slew-rate limitation must be imposed to avoid spontaneous oscillation. An editorial here might open by stating a firm belief that one has not applied a particularly linear discipline of spectral amplification if this is proven necessary, but that's for another time, and there are those who feel differently. It should suffice to say that in linear circuits this series resistance could reduce the gain-bandwidth product by giving more potency to Miller capacitance, as in any case where [parasitic] capacitances lurk in an increased-impedance environment.</p>

<p>Could someone explain what "bias" is.</p> <p>And why do some devices need an external bias resistor?</p>

What is the purpose of a bias resistor?

2010-03-24T14:35:12.020

2024

|arduino|ide|

<p>In Tinkercad there is a circuit function where you can place the arduino and all the other necessary components and program the virtual arduino using a scratch like interface. You can then copy the code on to the Arduino IDE.</p>

<p>I believe that the answer is no, but I wanted to check before I put effort into rectifying it (and no, no promises!)</p> <p>Is there anything like <a href="http://scratch.mit.edu" rel="noreferrer">Scratch</a> that one can use to program an Arduino?</p> <p>(Scratch is a graphical coding environment that makes learning to program fun, and is certainly suitable for elementary students. It is put out by the Lifelong Kindergarten Group at MIT).</p>

Is there a Scratch-like Arduino IDE?

2010-03-24T17:00:38.373

2036

|digital-logic|logic-analyzer|equipment|

<p>For a logic analyser, I highly recommend the <a href="http://www.saleae.com/logic" rel="nofollow noreferrer">Saleae Logic</a>.</p> <p><img src="https://i.stack.imgur.com/vKsVU.jpg" alt="Saleae Logic"></p> <p>There are two versions with 8 or 16 input channels. It can sample upto 24MHz or 50MHz depending on which one you buy. And the software can interpret the signals, allowing you to easily read I2C, SPI, CAN etc.</p> <p><img src="https://i.stack.imgur.com/LPoWL.png" alt="Saleae Logic Software"></p> <p>This has saved me, probably, hundreds of hours of my life. They aren't that expensive, especially considering how much time they save you. And the software works on Windows, Mac and Linux. Data can be exported to a a file, and there's even an API so you can write your own software for it if you really want.</p>

<p>Can anyone recommend a low cost or DIY buildable logic analyzer?</p> <p>Mostly, it would be for debugging serial protocols (SPI, I2C, RS232) at low voltages.</p>

Beginner's logic analyzer?

2010-03-24T23:12:27.253

2044

|arduino|enclosure|

<p>I just asked to seeedstudio to build something like that <a href="http://www.seeedstudio.com/wish/?p=939" rel="nofollow">http://www.seeedstudio.com/wish/?p=939</a></p> <p>please vote it if still interested, or in case you found a solution, please let me know...</p>

<p>I am looking for a way to put a Arduino with an Ethernet shield inside a DIN rail enclosure while exposing the RJ45 and a few screw terminals. </p> <p>Bare min: 55mm Width, 75mm length, 30mm height. Looks similar this <a href="http://arduino.cc/en/uploads/Guide/ArduinoWithEthernetShield.jpg" rel="nofollow noreferrer">http://arduino.cc/en/uploads/Guide/ArduinoWithEthernetShield.jpg</a></p> <p>Parts list: </p> <ul> <li><a href="http://www.sparkfun.com/commerce/product_info.php?products_id=9026" rel="nofollow noreferrer">http://www.sparkfun.com/commerce/product_info.php?products_id=9026</a> sitting on top of </li> <li><a href="http://www.sparkfun.com/commerce/product_info.php?products_id=666" rel="nofollow noreferrer">http://www.sparkfun.com/commerce/product_info.php?products_id=666</a></li> </ul> <p>The problem we are having is how to expose the RJ45 connector. </p> <p>We were thinking of finding an enclosure that supports a RJ45 Keystone and running wires from the board to the exposed terminals but we haven't found anything like that yet. </p> <p>We where also thinking about getting the two boards <a href="https://electronics.stackexchange.com/questions/1807/redesigning-the-arduino-duemilanove-and-ethernet-shield-in-to-a-single-board">redesigned in to a single board</a> that fits a existing enclosure. But that would cost 1000s of dolors. Or at lest thats what I been quoted. </p> <p>I been searching and phoning people for about a week without finding an answer. I'm looking for suggestions, hints, wild guess, anything?</p>

DIN rail enclosure for a Arduino + Ethernet shield

2010-03-25T18:05:56.020

2047

|reflow|bga|soldering|

<p>As part of my old job I had to build some boards with the Foxconn 478 pin BGA socket for the old P4s. It was the first component I put on the board. My technician and I did it by hand, using a little jig he made to line everything up right. You'll need a mask for screen printing the solder. I used post-it notes to set the snapoff distance, I think it was 2 or 3 post it notes thick. Reflow with a toaster oven (I had a nice reflow oven back then).</p> <p>We yielded about 8/10 boards, maybe a little less. Usually the fails had everything off a row, but occasionally one would line up between pads and short everything (big mess, obviously my pad masking wasn't quite right).</p> <p>So it's doable, by hand, if you are careful. Do it first, with nothing else on the board. If there are more than one BGA on the board your yield will be poor unless the pad spacing is large enough.</p> <p>It just occurred to me that we could have tried buzzing out the board; there were a pair of voltage sense pins that we could have used. That might have prevented some of the off-by-one-row alignment errors and shorting that we experienced, but the sockets were only about 5$ a piece.</p>

<p>BGA seems to be somewhat of a showstopper for the diy community, especially with the newer more powerful parts being almost exclusively bga. I know it can be done with the skillet/toaster oven method, but it seems like there is no way of inspecting for defects without an x-ray machine except for maybe this method <a href="https://web.archive.org/web/20150922174255/http://jlime.com/wiki/documentation/user/7xx/howtos/accesing_bga_pins" rel="nofollow">using toothbrush bristles</a>. So is reflowing using these methods relatively high yielding or is this just not worth doing at home?</p>

DIY BGA soldering feasability

2010-03-26T05:03:37.087

2086

|arduino|memory|sd|

<p>I haven't any of these toys but I saw this requirement for a TFT/LCD module including an SD slot : "You must use a micro SD card that supports the SPI interface, and is 2GB or less. Please note that not all uSD cards support SPI."</p> <p><a href="http://www.robotshop.com/eu/4d-systems-3-2-qvga-touch-screen-lcd-3.html" rel="nofollow">http://www.robotshop.com/eu/4d-systems-3-2-qvga-touch-screen-lcd-3.html</a></p>

<p>I got a new microSD <a href="http://www.arduino.cc/en/Main/ArduinoShields" rel="nofollow">shield</a> from LittleBird and am having some troubles with it.</p> <p>I downloaded the sample library that it said to used, threw in a microSD card and expected it to work... It won't initialise for some reason, and I have done a bit of googling and can't see how to get it working. Everyone just say use this library, use that one.</p> <p>Hardware</p> <ul> <li>MicroSD shield</li> <li><a href="https://www.arduino.cc/en/Main/arduinoBoardDuemilanove" rel="nofollow">Arduino Duemilanove</a> (<a href="https://en.wikipedia.org/wiki/ATmega328" rel="nofollow">ATmega328</a>)</li> <li>SanDisk (4 GB) microSD card (HC) </li> </ul> <p>Is the <a href="http://en.wikipedia.org/wiki/Secure_Digital#SDHC" rel="nofollow">SDHC</a> card part of the problem?</p> <p>I work off a Mac and even formatted the card on a Windows&nbsp;XP machine to fat 16, but still no luck.</p>

SDHC card, a microSD shield, and Arduino Duemilanove

2010-03-29T09:00:13.993

2089

|led|

<p>LED Shapes:</p> <p>"Bullet" - (traditional type) gives spotlight beam for flashlights</p> <p>"Strawhat" - (shorter lens) gives wider floodlight beam</p> <p>"Flat Top" - (as it says) gives wide spread light</p> <p>"Inverted Cone" (shown in original question) - gives sideways light all round, but less to the front</p>

<p>LEDs with a concave cone-shaped lens are sometimes called "straw hat" LEDs. What is the advantage compared to the more common hemispherical lens?</p> <p><img src="https://i.stack.imgur.com/y2tG6.jpg" alt="An example of this type of LED"></p>

What is the advantage of a "straw hat" (inverted cone) LED?

2010-03-29T14:21:17.983

2093

|power|relay|solid-state-relay|

<p>Suggest sending a zero pulse in the load circuit every so often .... keep the pulse time low such that any load like a motor doesn't stop as this might shorten its life. If the load is not at risk send a reset zero pulse every minute or so.</p>

<p>I'm trying to use a power relay (<a href="http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&amp;name=425-2359-2-ND" rel="noreferrer">PR26MF</a>) to turn on and off a device. The device takes a 9v supply and typically draws ~250mA. I'm finding that the relay turns on just fine, but when I try to turn it off, it won't: it remains latched in the on state.</p> <p>The datasheet mentions that a snubber circuit across the load may be necessary. I tried adding one (with a ~2ms time constant). It had no effect.</p> <p>I measured the resistance across the output port of the relay without the load attached; it works as you would expect: ~inf resistance when it's off and low resistance when on. It seems to turn on and off just fine in that setup.</p> <p>I tried a different load - using the SSR to drive a 5V mechanical relay. The SSR still exhibited the latching behavior.</p>

How can I stop a solid state relay from latching up?

2010-03-29T17:21:53.137

2097

|power-supply|components|power|

<p>After looking around I think I'm going to use a <a href="http://focus.ti.com/docs/prod/folders/print/tps60403.html" rel="nofollow">TPS60403</a>, it's got a higher switching frequency (250kHz) than the LMC7660.</p>

<p>I have a +5V power supply and need to invert to a -5V supply sourcing about 25mA. I've got an <a href="http://www.national.com/mpf/LM/LMC7660.html#Overview" rel="nofollow">LMC7660</a> running now. It's ok for the short term, it outputs -4.4V with 100mV p-p switching noise, but that's unacceptible for my long-term needs.</p> <p><strong>Anyone have any experience with LMC7660 / ICL7660 - like switched capacitor inverters?</strong> There must be some better parts on the market nowadays, we've had those LMC7660's in a drawer for at least 12 years. I can probably hunt something down, but figured I'd ask here.</p>

best quick&cheap power supply inverter

2010-03-29T20:02:13.910

2103

|breadboard|prototyping|

<p>I'd agree with many of the above, although breadboards are useable for low-power mains voltage applications with suitable external safety precautions (isolation, current-limiting/fusing).</p> <p>One thing you really shouldn't try to use them for is any sort of switching regulator. SMD is asily handled with breakouts - SM discretes can be easily soldered to 0.1" pin headers.</p> <p>The probability of dodgy connections means that larger designs are more prone to problems and should probably be avoided, but BBs are the ideal way to check out small bits of circuitry that you're not sure about. </p>

<p>What are the cases where one should avoid using a breadboard? e.g. high frequency, noise prone circuits etc.</p>

When to avoid using a breadboard

2010-03-30T16:49:34.643

2115

|antenna|analog|radio|

<p>I've used an RF switch from Skyworks for these purposes. The following is a nice app note from TI about doing it that explains a lot:</p> <pre><code>http://www.ti.com/lit/an/swra317/swra317.pdf </code></pre>

<p>Is it possible to have two antennas connected to the antenna port of an RF transceiver through some sort of mux? I want to be able to switch to a different antenna if the signal is weak on one. I would just use two of the RF modules but they are somewhat expensive.</p> <pre><code>ant2----------------------------- |---------| \________|2:1MUX|_________|RF module| ant1-----------------------------/ |---------| </code></pre> <p>edit: this will be for a 500-900Mhz system and both antennas are oriented differently, the case isn't that one antenna is high gain and the other not.</p>

Multiplexing an antenna

2010-03-31T21:57:37.977

2124

|transistors|bias|

<p>The simplified equations only work when you observe some basic assumptions. The most important being that the transistor is operating in it's linear region.</p> <p>Leave out the transitor for a moment. How much current would you get through Rc if it was connected directly between the 20V supply and ground?</p> <p>Then add in Re. You should end up with 20/(80 + 6.8) = 230 mA. This will be the maximum current that can possibly flow through the transistor. Given that there will be a small voltage drop across the transistor and errors from the resistor tolerance, that is very close to the measured value of 222mA.</p> <p>Depending on what you are trying to achieve you may need to reduce the collector resistor or reduce the targeted collector current.</p>

<p>I can't seem to get over this but this seems to be the basics in electronics. I have an NPN darlington transistor TIP122 and have built to simple test circuit around it with Rb = 150 ohm, Rc = 80 ohm and Re = 6.8 ohm. My base supply Vbb = 3.3V and collector supply Vcc = 20V. </p> <p>I have used the equation from <a href="http://www.allaboutcircuits.com/vol_3/chpt_4/10.html" rel="nofollow">this</a> site as mentioned for emitter biasing. </p> <blockquote> <p>Ie = (Vbb - Vbe)/(Rb/beta + Re)</p> </blockquote> <p>However I am getting different values theoretically and practically. </p> <p>With Re = 6.8 I get theoretical Ie = 273mA and practical Ie = 222mA then With Re = 6.8||6.8 I get theoretical Ie = 535mA and practical Ie = 228ma. </p> <p>I don't understand why could this be happening, how does the emitter resistor work in the transistor circuit... can you help me out?</p>

Transistor with emitter resistor calculation

2010-04-02T01:07:52.247

2130

|conductive|fabric|

<p>Sparkfun are now selling <a href="http://www.sparkfun.com/commerce/product_info.php?products_id=9770" rel="nofollow">conductive fabric</a></p>

<p>Does anyone know of a maker of Conductive Fabric?</p>

Conductive Fabric

2010-04-04T09:36:54.083

2145

|enclosure|

<p>Here are a few that I have bookmarked --</p> <ul> <li><a href="http://www.pactecenclosures.com" rel="nofollow noreferrer">http://www.pactecenclosures.com</a></li> <li><a href="http://www.polycase.com" rel="nofollow noreferrer">http://www.polycase.com</a></li> <li><a href="http://www.tekoenclosures.com" rel="nofollow noreferrer">http://www.tekoenclosures.com</a></li> </ul> <p>I don't have experience with any of these manufacturers (which is why I didn't post for the original question). I did receive samples from each company and all the cases look good and feel solid. Each company seems to have one or two styles that I like.</p>

<p>I have a small hw product and I would like to find a plastic enclosure company that do small runs. </p> <p>Recommendations with experience please (i.e. not a simple Google Search result dump!)</p>

Plastic enclosure for small product

2010-04-07T12:52:03.027

2151

|components|crystal|

<p>There seems to be a confusion between the size of a (quartz) crystal package, and the crystals' physical properties which include the crystal's size and it's resonant frequency due to its piezoelectric properties.</p> <p>In your photo, the crystal on the left appears to be a very common <code>HC-49/U</code> package size. The one on the right is most likely an <code>HC-49U/S</code>.</p> <p>From ICM, a crystal manufacturer, <em>"The frequency is a function of the thickness of the crystal. By carefully polishing or lapping a crystal, it can be made to oscillate at any frequency."</em> (<a href="http://www.icmfg.com/crystals.html" rel="nofollow">source</a>) In fact, amateur radio radio operators ("hams") historically were known to polish surplus crystals to their desired frequency, back when the cost of manufacturing was much higher. The practice was sometime referred to as "rock grinding." (<a href="http://s88932719.onlinehome.us/ham/rokgrind.htm" rel="nofollow">ref one</a> &amp; <a href="http://www.bliley.net/XTAL/docs/misc/XTAL_grinding/grinding.html" rel="nofollow">ref two</a>)</p> <p>You can verify this by looking at a manufacturers' specifications for crystals in different packages. </p> <p>E.g. <a href="http://foxonline.com/thruhole_xtals.htm" rel="nofollow">FOX through-hole crystals</a> and <a href="http://www.icmfg.com/thruhole_crystals.html" rel="nofollow">ICM</a>, where in fact the larger package includes overtone crystals (<a href="http://www.foxonline.com/pdfs/osctheoryoper.pdf" rel="nofollow">page 3, PDF</a>) for higher frequencies (looking at HC-49/U and HC-49/S). At fundamental frequencies they are often the same frequency range available.</p>

<p>Here is a picture of two crystals: <img src="https://i.stack.imgur.com/vdFPQ.jpg" alt="two crystals"></p> <p>Does the difference of frequency explain why the 6 MHz crystal on the right has a lower profile than the 5 MHz one ?</p>

Does the frequency of a crystal influence its height?

2010-04-08T09:16:44.313

2156

|usb|host|atmega|

<p>Atmel provide host and device firmware for their AVR32B family of processors. These have built in USB 2.0 OTG hardware. The EVK1101 development board is a good hardware target and the AVR studio is a free GNU development environment. FreeRTOS has been ported to this platform and is a good stable base to work from.</p> <p>There are also ARM Cortex-M3 parts that have the same capability and cheap/free tools.</p>

<p>I am looking at creating a USB host devices to talk to a standalone printer. Basically my devices would feed out commands to the USB chip and the pritner would print it without interaction of a PC.</p> <p>What chips would you recommend for the USB/MCU? I am leaning towards an ATMEGA micro with a Vinculum USB interface. Would it be easier to use a all in one chip or have a seperate MCU and USB chip?</p> <p>Thanks</p>

USB Host device

2010-04-09T02:57:35.953

2165

|pcb|protoboard|

<p>Consider barebonespcb.com . You didn't mention your budget but this is as cheap as it gets in the US from my experience (e.g. two 2"x2" boards for $54 total). No stop mask though. </p>

<p>Recently I have been trying to get myself an arduino made by hand (as where I live the original one costs about 10x and its fun to make things on your own). I made a compatible on the breadboard and tested it using the blinky program. Now I want to make it on a PCB. The problem is getting a PCB manufactured is also not so cheap (if you are getting only one board). So I was thinking I would use a prototype board. I have used those once before and it was a clear mess. I kept shorting IC pins while connecting lines to them fried a whole PCB (actually fried it, the LEDs went BOOT, the IC went WOOSH and the wires turned to a general copper ting). All in all it was a not so good experience. I attribute this failure to my incompetence in soldering on the prototype boards. I can do a clean solder on any PCB in a kit but I think prototype boards are a different ball game. </p> <p>So I ask you all of any tips you may have on using such boards.</p> <p>Thanks in advance.</p>

Tips on using a Prototype PCB

2010-04-09T14:33:01.367

2178

|charging|batteries|arduino|inductive|

<p>The guys over at seeedstudio sell a <a href="http://www.seeedstudio.com/depot/wireless-power-supply-p-701.html?cPath=155" rel="nofollow">ready-made inductive transmitter/receiver pair</a>, designed specifically for charging batteries. </p> <p>I have no experience with it, but at $\$$9.50 it might be worth a shot.</p>

<p>I've build a small three wheel robot with an Arduino Mega to drive the thing. I'm looking to keep this bot mobile as much as I can without needing to interact with it for charging etc.</p> <p>For the moment I am running on a collection of normal AA batteries as the power source. I'd like to replace this with an appropriate rechargeable battery pack, and a charging circuit of some kind.</p> <p>So I'm after two things.</p> <ol> <li><p>Information on charging circuits. I feel like I am searching for the wrong thing, and am not coming up with anything useful.</p></li> <li><p>Inductive charging. I really would like to be able to park the robot on a charging base, and leave it there, and have it just drive off the base when its done. Most articles I can find say to rip apart an electric toothbrush for this. But I would love to do it myself.</p></li> </ol>

Inductive Charging

2010-04-10T23:37:33.973

2180

|charging|discharge|passive-networks|

<p>If your square wave frequency is low enough the RC filtered signal will follow the square wave closely, although with less steep edges.<br> But this needs 5T (RC time constants) to more or less reach you 5V or 0V; after 5T about 99% of the final value is reached. </p> <p>In our case </p> <blockquote> <p>\$1T = RC = 3300\Omega \times 100nF = 330\mu s \$</p> </blockquote> <p>and one period is \$ 1000\mu s\$, so a half period is only 1.5T. That means that the signal doesn't have the time to reach 5V when going up, or 0V when going down: </p> <p><img src="https://i.stack.imgur.com/PqKVq.png" alt="enter image description here"> </p> <p>whereas for a shorter time constant the signal would more look like this: </p> <p><img src="https://i.stack.imgur.com/crim2.png" alt="enter image description here"> </p> <p>Note that in the second case (this is for a time constant \$T = 33\mu s\$) the signal reaches both 5V and 0V, while it doesn't for our case; the time is simply too short. </p> <p>Now about the 2V you're measuring. If you measure this with a DMM it's easy to explain: the DMM averages the measured value. If you actually see it on a scope it probably looks a bit like this: </p> <p><img src="https://i.stack.imgur.com/jb2ac.png" alt="enter image description here"> </p> <p>This shows the same effect we saw earlier: the time constant is way too long, and the capacitor has hardly the time to start charging and discharging. Here \$T = 3.3ms\$.<br> If this is what you see there might to be something wrong with your components; check if they're really \$3300\Omega\$ and \$100nF\$. If the values are right you may have an extra impedance in series with the resistor.</p>

<p>I am trying to understand the principles of a RC charging / discharging circuit however I'm at loss regarding certain aspects of its operation.</p> <p>I have a square wave generator giving 0v to 5V levels at certain frequency, say 1Khz at 50% duty cycle. My R = 3.3K and C = 100nf. </p> <p>My thinking is that if the capacitor charges during the high state of the generator and discharges equally during the low state of the generator. Then it shouldn't have any charge left and should remain at that level(uncharged). However when I try it practically I find that eventually the capacitor charges to some mid level, that is 2V which my mind can't really comprehend. </p> <p>Does the capacitor charge and discharge and different rates in an RC circuit what exactly is going on over then I can't really explain, can you?</p>

RC circuit understandings

2010-04-11T03:29:59.097

2185

|i2c|7segmentdisplay|spi|

<p>There are many I/O Expanders out there that use either SPI or I2C buses. With a single MSSP module you can control almost an infinite amount of digital outputs like LEDs. Depending on the current draw of the LEDs in your 7seg display you may be able to control them with an I/O expander like the <a href="http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en021393" rel="nofollow">MCP23008</a>. Check the datasheets for your display and the MCP23008.</p>

<p>Does anyone know of any good I2C 7segment display drivers. I swear a previous answer referenced a chip for this on chiphacker but I cannot find it.</p> <p>I would also be happy with SPI, but I I2C would work better as I plan to use many 7Seg.</p>

I2C 7seg driver

2010-04-11T22:25:36.390

2192

|sensor|measurement|accelerometer|

<p>How about a cheap dev kit that has a accelerometer?</p> <p>There is a couple of them to choose from but maybe the <a href="http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATA_BRIEF/CD00171996.pdf" rel="nofollow">STM32 Primer</a>, and <a href="http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&amp;name=497-6049-ND" rel="nofollow">digikey</a> used to sell those for approx 48$. It was deprecated in favor of the <a href="http://www.stm32circle.com/resources/stm32primer2.php" rel="nofollow">STM32 Primer 2</a> for which the <a href="http://www.digikey.com/product-detail/en/STM3210EPRIM-D/497-10854-ND/2499969" rel="nofollow">plugin board</a> is less expensive but the <a href="http://www.digikey.com/product-detail/en/STM3210CPRIMER/497-10858-ND/2499965" rel="nofollow">base kit</a> is significantly more expensive.</p> <p>A extra little feature is that this is a usb-based dev kit, so you can send the data to a computer and create a "data-logger".</p>

<p>For growing crystals it is important that there are no vibrations. Is there a cheap and easy way to measure vibrations in the floor, like people walking, doors closing etc.?</p> <p>Perhaps an accelerometer is possible, but those are pretty expensive (Nun chuck is less expensive).</p>

Vibration sensor (accelerometer?)

2010-04-12T13:31:44.487

2194

|audio|capacitor|

<p>As long as the DC level is positive, the AC amplitude of the audio signal is of no consequence because it is a "coupling" capacitor, in the sense that the RC time constant is much higher than the highest 1/f of the audio signal (excluding dc of course), so the capacitor never gets "charged up" to the audio ac signal voltage (only to its dc value). Instead, the voltage across its terminals remains approximately constant. In other words, the capacitor rides with the input, and if the RC constant was not high enough, audio would be distorted. For example, you could have 1V of dc offset and 10V of ac amplitude. If RC is high enough, the voltage accross the capacitor will ALWAYS be very near 1V,NOT 11V to -9V as the comment to the first answer seemed to imply. Hope this helps.</p>

<p>I've seen circuit diagrams that use a polarize electrolytic to remove DC offsets from an input audio signal.</p> <p>The cap is polarized. Why is this ok?</p>

Why is it ok to use polarized caps to remove DC offset from an audio input?

2010-04-12T13:50:29.263

2205

|capacitor|microcontroller|

<p>At high frequency the impedance of the inductor increases and the impedance of the capacitor decreases. For high frequency signals most of the signal voltage drop is across the inductor.</p> <p>The VCC (in a properly designed system) will have a very low impedance. By raising the impedance between VCC and AREF the capacitor will reduce more of any high frequency noise that is on VCC. </p> <p>On my boards I use a 10-20uH inductor and 0.1uF capacitors.</p> <p>[corrected the first paragraph mistake that leon commented about]</p>

<p>The ATMEGA datasheet suggests filtering the ADC reference voltage with an LC network, in other words VCC - L - AREF - C - GND. How does the inductor smooth the voltage better than just a capacitor?</p>

How does an LC network filter power?

2010-04-12T19:10:12.333

2209

|jtag|

<p>It would be best to match your tool. <a href="http://www.jtagtest.com/pinouts/" rel="nofollow">This site</a> lists quite a few (doesn't have any references, so double-checking is an absolute must before you lay it out)</p> <p>For AVRs, <a href="http://www.jtagtest.com/pinouts/avr" rel="nofollow">their recommended pinout</a> matches what the <a href="http://www.atmel.com/dyn/resources/prod_documents/doc2562.pdf" rel="nofollow">AVR JTAGICE mkII</a> uses (see page 3).</p>

<p>I see a lot of device specific JTAG cables such as AVR jtag or specific ARM JTAG. Is there any such thing as a 'standard' JTAG cable that will work on multiple devices? I want something that will work with xilinx FPGAs, STM32s and AVR microcontrollers</p>

JTAG cable and device interchangeability

2010-04-12T21:50:24.553

2211

|avr|motor|

<p>I don't know why you placed the diode in series with the motor; it's not needed there. Which doesn't mean that it's completely wrong, it's just in the wrong place.<br> You use a diode to isolate the motor from the ATtiny, but you'll have to place the diode in front of the 0.22\$\mu\$F capacitor, and connect the motor directly to the 9V source. (By the way, the 0.22\$\mu\$F is way too small; make it a 500 times larger, so 100\$\mu\$F. Place a 1\$\mu\$F in parallel.) Now if the motor draws current it only can draw it directly from the 9V supply, not from the capacitor, so negative spikes won't reach the ATtiny's power pin. </p> <p>You also have to place a flyback diode over the motor, anode to the transistor's collector.</p>

<p>I've recently begun experimenting with AVRs and am keen to progress beyond making blinkies to making things <em>move</em>. I've tried to start with something easy, but it seems I'm already foiled! What I'd like to know is this: is it possible to drive both an AVR and a motor from the same power source and without them interfering with one another?</p> <p>The schematic below illustrates my initial attempt at doing this. The ATtiny is generating a ~3kHz PWM signal (1/3 duty cycle) on pin 5, with the intent of supplying a time-averaged voltage of 3V to the motor via the power transistor. When I wire this up though, the motor just seems to cough and sputter. <img src="https://i.stack.imgur.com/XS4Rp.png" alt="alt text"></p> <p>Thanks heaps in advance,</p> <p>Tim</p> <p>p.s. I'm just wondering about the fundamental possibility/impossibility of what I'm trying to do: I don't expect anybody to debug my circuit for me! :-)</p>

Driving a DC hobby motor using an AVR and a single power supply

2010-04-13T02:45:35.763

2226

|microcontroller|system|

<p>I don't see why is it hard for you to find hardware to run existing DOS system? Some ARM Linux SBC could be found for less then 100$ (plus external modem), but why going through all the platform change trouble if current solution runs well? Find some x86 SBC board as a temporary solution, and then only make platform change if you need new features hardly achievable with DOS. Platform change and rewriting all from scratch is very, very time consuming, and can eat all the budget if you don't have a backup plan. And I think you have one. Just googling with words "smallest" "dos" "sbc" gives enough hits for you to start.</p>

<p>A bit of background: We have a system currently in production, but the original programmer passed away, and the current hardware manufacturer cannot find hardware to run the (currently) DOS system, so I need to re-implement this in a more modern platform. I can only change the programming and the motherboard hardware.</p> <p>I asked over in StackOverflow and was suggested I ask here.</p> <p>I am new to the locating hardware side of embedded programming and so after being completely overwhelmed with all the choices out there (pc104, arduino, rabbit, custom boards, a zillion options for each board, beagle, volume discounts, devel kits, ahhh!!) I am asking here for some direction borrowing from your experience. (What would you do?)</p> <p>Basically, I must find a new motherboard and (most likely) re-implement the program logic. Rewriting this in C/C++/Java/C#/Pascal/BASIC is not a problem for me. so my real problem is finding the hardware. This motherboard will have several other devices attached to it. Here is a summary of what I need to do:</p> <p>Software requirements: Very minimal. No need for RTOS or multitasking, very low CPU requirements, I just need something I can program and something I can put a remote update mechanism into (updates to the code will be downloaded via modem maybe 1-4 times a year).</p> <p>Required hardware:</p> <ul> <li>2 RS232 serial ports (one used all the time for primary UI, the second one not continuous use [it's a serial printer])</li> <li>1 modem (9600+ baud ok) [Modem will be in simultaneous use with only one of the serial port devices (UI), so interrupt sharing issues with one serial port is OK, but not both]</li> <li>Minimum permanent/long term storage: Whatever O/S requires + 1 MB (executable) + 512 KB (Data files)</li> <li>RAM: Minimal, whatever the O/S requires plus maybe 1MB for executable.</li> </ul> <p>Nice to have:</p> <ul> <li>USB port(s)</li> <li>Ethernet network port</li> <li>Wireless network</li> </ul> <p>Implementation languages (any O/S I will adapt to):</p> <ul> <li>First choice Java/C# (Mono ok)</li> <li>Second choice is C/C++/Pascal</li> <li>Third is BASIC</li> </ul> <p>Ok, given all this, I am having a lot of trouble finding hardware that will support this that is low in cost. Every manufacturer site I visit has a lot of options, and it's difficult to see if their offering will even satisfy my must-have requirements (for example they sometimes list 3 "serial ports", but it appears that only one of the three is RS232, for example, and don't mention what the other two are, or how much it costs (or is even possible) to make it RS232). The #1 constraint is cost, #2 is size.</p> <p>Can anyone help me with this? This little task has left me thinking I should have gone for EE and not CS :-).</p> <p>Also, please let me know if I can phrase my question any better.</p>

How to find an embedded platform?

2010-04-13T16:54:06.347

2235

|rfid|sensor|usb|

<p>Have you tried using a powered USB hub?</p>

<p>I am hoping someone here can help me.</p> <p>I am having trouble with a RFID kit I bought from SparkFun. I purchased the <a href="http://www.sparkfun.com/commerce/product_info.php?products_id=8852" rel="nofollow noreferrer">USB RFID (SEN-08852)</a> with the <a href="http://www.sparkfun.com/commerce/product_info.php?products_id=8419" rel="nofollow noreferrer">RFID Reader ID-12 (SEN-08419)</a> and some RFID cards.</p> <p>When I hook up the reader or try to use it, it goes into a constant "read" mode. The green "Read" LED flashes constantly and the buzzer clicks with each flash. This will not stop until I unhook the USB cable. </p> <p>I have found that if I connect the USB part without the reader and then connect the reader to the board, the device works properly for the very first RFID card (and I can read the serial output using PuTTY). As soon as the first card is read, it starts the read loop again. </p> <p>Any ideas as to why this is happening? Is my device broken, or am I just doing something wrong? </p> <p>I have Windows 7 x64, and I did not install any drivers when I hooked up the reader - Windows downloaded them for me.</p> <p><strong>Edit:</strong> Apparently the port I was using wasn't providing enough power for the reader - once I tried a powered hub (and eventually another port on my laptop), it was working flawlessly! I now have no problems swiping a card more than once.</p>

Problems with a RFID reader from SparkFun

2010-04-14T16:52:06.607

2245

|zigbee|development|board|wireless|

<p>If you are into the home automation, why don't you opt for real thing? It's called <strong>Z-Wave</strong>, a the facto industry standard for wireless home automation (the next X10), and there are hundreds of products Z-Wave enabled. Digikey has boards and dev kits, and there is even a small power plug linux box with Z-Wave and ethernet embedded.</p> <p><a href="http://www.z-wave.com/modules/Products/?id=66&amp;chk=94b8927269761c1a0c94de9268724ddb" rel="nofollow">http://www.z-wave.com/modules/Products/?id=66&amp;chk=94b8927269761c1a0c94de9268724ddb</a></p> <p><a href="http://web1.zen-sys.com/modules/Products&amp;Techonology/?id=33&amp;chk=7c18247ff46da755b3d1753888e2a342" rel="nofollow">http://web1.zen-sys.com/modules/Products&amp;Techonology/?id=33&amp;chk=7c18247ff46da755b3d1753888e2a342</a></p> <p><a href="http://www.tricklestar.com/US/300ZW_US_W.html" rel="nofollow">http://www.tricklestar.com/US/300ZW_US_W.html</a></p> <p><a href="http://www.ionicsplug.com/stratusplusplus.html" rel="nofollow">http://www.ionicsplug.com/stratusplusplus.html</a></p> <p><a href="http://www.digiwave.dk/en/programming/an-introduction-to-the-z-wave-protocol/" rel="nofollow">http://www.digiwave.dk/en/programming/an-introduction-to-the-z-wave-protocol/</a></p> <p><a href="http://www.digiwave.dk/en/programming/an-introduction-to-z-wave-programming-in-c/" rel="nofollow">http://www.digiwave.dk/en/programming/an-introduction-to-z-wave-programming-in-c/</a></p> <p><a href="http://www.smarthome-products.com/p-625-homepro-zcu201-z-wave-usb-interface-euro.aspx" rel="nofollow">http://www.smarthome-products.com/p-625-homepro-zcu201-z-wave-usb-interface-euro.aspx</a></p> <p><a href="http://plugcomputer.org/plugforum/index.php?topic=1462.0" rel="nofollow">http://plugcomputer.org/plugforum/index.php?topic=1462.0</a></p>

<p>i want to start a home automation project, so finally i choose zigbee as the communication system between the devices. I need something easy to start, so, what do you recomend to buy? there is some nice starter or development kit, with something like RS232 or USB output, just to forget about the zigbee protocols and issues, i need something that almost works out-of-the-box...</p> <p>thanks! Br</p>

Zigbee starter kit, any suggestions?

2010-04-15T19:38:22.717

2254

|pic|programmer|

<p>Apparently there is a problem with the device file that comes with v1.20 of pk2cmd.exe.<br> Reverting to the device file that comes v1.01b of pk2cmd.exe fixes the issue.<br><br> Working configuration:<br> - PK2CMD.EXE v1.20<br> - Device File v1.42.00 (Comes with PK2CMD.EXE v1.01b)<br> - PICkit2 Firmware v2.32.00</p>

<p>I'm having a problem programming a PIC18F97J60 with pk2cmd.exe. Using the same hex file I can program the device fine with MPLAB and the PicKit2 programming utility, but I'd like to be able to program the chip from the command line. The chip will program, but verify fails. I should mention that I have the code protect bits set on the PIC18F97J60.</p> <p>Original Configuration:<br> - PK2CMD.EXE v1.20<br> - Device File v1.55.00<br> - PICkit2 Firmware v2.32.00</p>

Problem programming PIC18F97J60 with PicKit2

2010-04-16T14:34:11.220