hybridfree/eevblog-posts huggingface dataset:
Having an ESP32 control a reed switch with wifi and deep sleep on LIPO battery - Page 1
Forum section: electronics / projects

author: Stealthrt
author_rank: Regular Contributor
timestamp: November 12, 2021, 05:22:48 pm
content: I’m looking to create a project for my home. I am wanting to place window and door sensors (reed switch) and hook it up to my ESP32 wroom-32 (wemos) microprocessor. The version I have has the JST connector to hook up a LIPO battery to. I have 20 of these to use with a reed switch and a custom 3D printed enclose for it.I found the website that allows me to input the specs of my esp32 and see how long the battery would last depending on the size of the battery. For my math I came up with the following:Capacity rating of battery = 1700mAhCurrent consumption of device during sleep = 0.02 mACurrent consumption of device during wake = 5 mANumber of wakeups per hour = 120 (every 2 minutes)Duration of wake time = 1000 msThis puts it just shy of 1 year (323.7 days) on the LIPO only.I plan on utilizing the deep sleep function that the esp32 has. I’ve seen that its around 150 µA (0.15 mA) and replacing that value with the one provided above (0.02 mA) with the calculator gives me an even lower amount of days. So, I will only wake it up using the external source which would be the reed switch (ext0/vp) and use the Timer function to send and receive data every 2 minutes and then go back to sleep for another 2 minutesThe big question I have though is this – How much does waking every 2 minutes, turning on the Wi-Fi and RX/TX a json string take in mA? Each time I am wanting it to send via WIFI a json string to my home server API to let update my dashboard so it knows that esp32 status (open or closed window/door) and battery level (10-100%).Now the even bigger question is – how would I be able to send a command to the esp32 to let it know if it needs to alarm when it detects the reed switch connection or if I simply want to open the window to get some fresh air without it tripping the alarm? That can be done with every 2 minutes it wakes and send data – I could just send json string back letting it know to not worry if the reed switch is tripped or not. But again, I do not know how much current all that would take to achieve all this?So, to summarize:- I want to place the esp32 into deep sleep every 2-5 minutes.- I want to send a json string every 2 minutes to my API.- I want to send back a json string for “disable” to not care about the reed switch status or “Enable” which would mean to care about the reed switch status.- I want to turn on the Wi-Fi just enough to be able to send and receive json data.I’m sure there’s somebody out there that has done this type of setup or close to it that can lend some helpful advice.
Having doubt on noise countermeasures in DC-DC - Page 1
Forum section: electronics / projects

author: vignesh_shan
author_rank: Contributor
timestamp: December 04, 2020, 05:07:14 am
content: HI ,I have read an article. In that article, the noise frequency is 200MHz, but they are saying that they added 2200pF (160MHz resonance frequency) capacitor to suppress that noise. My doubt is if we use 160MHz resonance freq capacitor, it will be act as inductor right ?.Anyone please read it and explain to me !!!Link:https://techweb.rohm.com/knowledge/emc/s-emc/03-s-emc/7586THanks,Vignesh.M

author: dietert1
author_rank: Super Contributor
timestamp: December 04, 2020, 07:25:24 am
content: The impedance diagram of that 2200 pF capacitor shows the impedance minimum at 160 MHz that results from series resonance, where L is the parasitic inductance of the part (package). Of course you are right that at higher frequency that parasitic inductance dominates impedance. So a part with 200 MHz resonance could be performing better, but apparently that 2200 pF was the best they found. A smaller capacitor will have a higher resonance frequency, but its (minimum) impedance at 200 MHz will probably not be much lower, because parasitic inductance will be similar.Regards, Dieter

author: David Hess
author_rank: Super Contributor
timestamp: December 04, 2020, 04:58:17 pm
content: I have seen through-hole layouts where 5% film capacitors were used for decoupling with carefully tuned trace lengths to notch out specific frequencies. I doubt this is ever necessary on surface mount designs using ground plane where lead lengths can be so short.

author: dietert1
author_rank: Super Contributor
timestamp: December 04, 2020, 05:14:30 pm
content: Yes, if you see the numbers in that paper (reduction of spike from 180 mV to 100 mV), i guess the same improvement could have been achieved without resonance, just placing a second 22 uF or any other SMD cap. The parasitic inductance that dominates with larger capacitors, should be lower with a small package but in this example that doesn't seem to be the case. Maybe the 2200 pF solution is preferable because it achieves a similar result with less material.Regards, Dieter

author: Vovk_Z
author_rank: Super Contributor
timestamp: December 04, 2020, 09:55:09 pm
content: 1. As I see 2200 pF value was chosen by accident, just for an example.2. It doesn't make the main problem if a blocking cap is an inductor or not. The main thing is an impedance of a cap.So they just show there in the article that a cap with a resonance frequency of 160 MHz helps. But some another value cap will help too (possibly even cap with it's resonance freq. of 3-10 MHz will help too). Except a cap with value that will help to resonate at some parasitic resonance frequency.
Having fun with PUTs Programmable Unijunction Transistors - Page 1
Forum section: electronics / projects

author: schmitt trigger
author_rank: Super Contributor
timestamp: January 26, 2019, 10:34:08 pm
content: A follow up of a previous thread.https://www.eevblog.com/forum/projects/having-fun-with-discrete-transistors/msg2108917/#msg2108917I have continued to play with discrete semiconductors, ....I am just sharing the fun.Most everyone, at least if you are nearing retirement age, has seen the bipolar transistor astable multivibrator.This is a classic circuit:http://www.davidbridgen.com/astable.htmA little rarer is theprogrammable unijunction transistorastable multivibrator. I remember seeing a description in an old GE SCR manual, 5th edition. See the attached image and description.Assembling the circuit, and probing the cathode for each device, one can see the alternating pulses.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 27, 2019, 07:08:09 am
content: Nice that it only uses one capacitor -- reminds me of the CD4066 oscillator and such.Tim

author: schmitt trigger
author_rank: Super Contributor
timestamp: January 27, 2019, 05:48:20 pm
content: An acquaintance of mine would joke that the PUT is the triple-lie semiconductor:-It is not programmable, it’s parameters are adjustable.-It is not an UNI-junction, it actually has three junctions like a SCR.-It is not a transistor, as it cannot operate linearly. Again and similar to the SCR, which is a thyristor, it operates either off or triggered.

author: Ian.M
author_rank: Super Contributor
timestamp: January 27, 2019, 07:52:46 pm
content: You used to be able to get one with both anode and cathode gates, theBRY39, in a four lead TO-72 metal can package. It could operate as a normal (low power) thyristor, or as a PUT, which obviously gave you extra triggering options. Although its still available N.O.S. from various specialist suppliers, prices have unfortunately gone crazy.

author: schmitt trigger
author_rank: Super Contributor
timestamp: January 28, 2019, 01:41:57 am
content: This is really a unique component.Thanks for sharing, I have never seen this device applied in a circuit.
Having multiple switching power supplies on one PCB - Page 1
Forum section: electronics / projects

author: Corporate666
author_rank: Unknown
timestamp: March 04, 2013, 07:04:09 am
content: I haven't really worked with a design that needed multiple power supplies on a single board where those supplies would be switchers - which leads me to a question.Let's say you have a device that requires 5V and you're running on batteries such that your input voltage could vary between, say 4.5 and 6 volts depending on charge. Let's also say you need a 12V rail on the board as well.Is there any problem using a boost regulator on the incoming voltage to bump it to 12V, then having a separate buck regulator taking that 12V down to 5V for the 5V rail?In other words, taking the output from a boost regulator and using it as the input of a buck regulator?My gut tells me this is done all the time and should be no issue (especially considering switching power supplies externally), but maybe there are some design tips I am not aware of? Maybe something like separating out ground planes, or making sure the frequencies are sufficiently far apart, or putting extra capacitance, etc?

author: AndyC_772
author_rank: Super Contributor
timestamp: March 04, 2013, 07:38:41 am
content: No issue at all, in principle. There are a few things to consider, though...If you're making a commercial product which will have to go through EMC testing, it might yield worse emissions if both supplies' switching events happen simultaneously, as the resulting switching noise can add constructively and push the overall emissions higher. The opposite can also be true! Sometimes it's better to synchronise them together, sometimes not.If you cascade two supplies, the overall efficiency is affected. Say you have two supplies each of which is 80% efficient, and they're joined together. Power drawn from the second supply incurs losses in both, so you only actually get 64% efficiency overall. Try to draw as little power as possible from supplies which are further down the chain from the main supply to the board. So, for example, if your circuit draws the most power from the 12V rail, then the circuit you suggest would be fine. If it draws the most power from the 5V rail, you might like to consider generating the 12V supply from 5V rather than the other way around. (Or perhaps not in this case, as a circuit that can generate a stable 5V from 4.5-6V is likely to be less efficient than a buck or boost converter).
Having problems with the philips saa1099 soundchip. - Page 1
Forum section: electronics / projects

author: 0w0wkazii
author_rank: Newbie
timestamp: December 25, 2010, 07:07:58 pm
content: Hi everyone,First of all, this is my first time here and I have searched before I was going to post my topic.For my schoolproject, I have to use a soundchip to produce different kinds of frequentie tones. I've chosen for the Philips saa1099. It's a old soundchip and it's pretty much obsolete. To program this soundchip, I'm using a PIC18F2550. Problem is I have been working on this for 2 weeks now and result = nothing. I can't get this soundchip to work and actually from what I've seen in the datasheets, it's looks simple to program.you have 1 databus with 8 pins to send 1 byte at a time parallel. And you have three more other pins: /WR, /CS, A0. the first one is the write enable then de chip select and finally the control/adress select. the /WR en /CS as you can see are active low pins so I send a '0' to activate it. and if A0 = 0, the data you send is the register adress. and if A0=1 then the data is the data of the register itself. So to configure the soundchip, you must first send the register adres and then the data that goes in this register.So in the end, it isn't really that hard to program this. So I've done everything, I configure every register needed to generate a frequencytone. and stil I don't get any results. I have used the hardware schematic from the datasheet itself (http://velesoft.speccy.cz/saa1099-cz.htm) and I've also used this website for some explanation of the chip (http://www.onastick.clara.co.uk/sound.htm).After so many effort, I can't really understand why this thing doesn't work. It looks really simple to program but yet it isn't for some reason. And I've spend alot of time finding some information on the internet, but it seems like that I'm the only one that is doing this lol.So if there are people that have more experience with this soundchip or electronics in general. Please help me out. This is a very important project that I have to do for my school and it's getting frustrating.thx in advance,0w0wkazii.

author: djsb
author_rank: Super Contributor
timestamp: December 26, 2010, 10:27:59 am
content: Have you got a copy of the schematic circuit that you have actually built (or at least a photograph of something on a breadboard/PCB). Have you connected the CLK pin to an 8MHZ clock source?If we can see what you have wired up we may be able to help.

author: GeoffS
author_rank: Unknown
timestamp: December 27, 2010, 02:18:50 am
content: Have you considered a more recent sound chip?The saa1099 is hard to source, not even sure if they still make it.

author: JohnS_AZ
author_rank: Frequent Contributor
timestamp: December 27, 2010, 04:19:25 am
content: Would have to see some kind of schematic tohelp.The first thing that entered my mind was "Where the HECK did you come up with an saa1099?"I would love to have a few of those to play with.
Having trouble finding a Female PC-Sync connector (COMPONENT HUNT) - Page 1
Forum section: electronics / projects

author: Ferroto
author_rank: Frequent Contributor
timestamp: January 03, 2011, 06:07:10 pm
content: I'm looking for a female PC Sync connector, so far I've checked mouser, and digikey and had no luck.A PCsync cable is a cable used to connect a flash head to a camera as an alternative to a hotshoehttp://en.wikipedia.org/wiki/Flash_synchronizationI'm looking for a cable like this so I can make a high speed flash trigger. It will use a laser and a photo transistor or a microphone to trigger the flash during a high speed event such as a water balloon bursting or a bullet in mid air.Basicly I set a long exposure in an area where the only light source is the flash. And then the flash can go on and off faster then the shutter can open\close. This allows me to take images of objects that are too fast for my cameras shutter.I was wondering where I could find the female version of this connector.

author: scrat
author_rank: Frequent Contributor
timestamp: January 03, 2011, 06:16:45 pm
content: You can make your own, or try to find a power supply connector that fits there.

author: Ferroto
author_rank: Frequent Contributor
timestamp: January 03, 2011, 06:26:18 pm
content: This is basically what I'm looking forhttp://en.wikipedia.org/wiki/Prontor-CompurI would just cut the end of that cable off and wire it directly to my design but I want a more professional design.

author: Zyvek
author_rank: Regular Contributor
timestamp: January 03, 2011, 07:37:56 pm
content: If quantity is not an issue, You could buy something like this:http://cgi.ebay.com/Flash-Hot-Shoe-PC-Sync-Cord-Socket-Adapter-Camera-/150538554843?pt=Camera_Flash_Accessories&hash=item230ccc0ddband remove the socket you need.Without going into further detail , this is not the only common connector for a camera flash (studio strobes use "household" as well as 1/4" and 1/8" type connectors) , you could use one of these make a conversion cable..Check:http://www.bocaphoto.com/products/new/lighting/index.htmabout halfway down the page under "Flash Sync Cords" for some ideas. Most of my old flash slaves require a male PC cord to another connector.Just a few ideas, but they might not fit your design requirements...

author: OhmEye
author_rank: Contributor
timestamp: January 05, 2011, 06:09:52 am
content: Is this it?http://www.colinsfoto.com/-Prontor_Compur_PC_Sync_Chassis_Connector/p43950_835874.aspxThis seems to be some commentary on the connector history:http://strobist.blogspot.com/2010/02/its-time-for-pc-jack-to-die.htmlI agree with his suggestion to use a standard 3.5mm connector if you can.

author: Mechatrommer
author_rank: Super Contributor
timestamp: January 05, 2011, 03:30:01 pm
content: Quote from: OhmEye on January 05, 2011, 06:09:52 amme too! very hard to get the pc synch supply in ebay. bookmarked the link, and when i got my photography ee project done with 3.5mm jack, i will tell the guy and hope he will listen and publish/promote it.
Having trouble with a lcd controller. - Page 1
Forum section: electronics / projects

author: David97
author_rank: Contributor
timestamp: September 08, 2015, 11:15:35 am
content: Hi everyone. I'm having trouble with a lcd controller board a picked up off ebay. I bought this cheap and was planning a build of a fpv ground station around it. I also bought a cable to hook it up and a lcd pannel.http://www.ebay.com/itm/121544812588?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIThttp://www.ebay.com/itm/400728937417?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AITThe panel is a LP150X08_A3, which is listed as a supported panel under the listing.I have installed the correct firmware for the panel, however when I hook it up I don't get anything on the display. I have tried it on another panel (LM185WH1) and it works fine. I'm not sure what's going on. Perhaps I bought the wrong LVDS cable?Any help would be greatly appreciated. Thanks!
Having trouble with a voltage doubler circuit....  - Page 1
Forum section: electronics / projects

author: DaveHardy
author_rank: Regular Contributor
timestamp: June 20, 2012, 11:20:56 pm
content: I'm having some strange problems with this circuit. I'm trying to get 100V DC where the blue probe is in my picture. Unfortunately, I am only getting about 25V when measured from the green probe (ground) to the blue probe (output). However, if I measure from the red probe to the blue probe, I get the full voltage without any loading effects.I've tried numerous configurations and have had mixed luck so far.Can anybody help me?

author: T4P
author_rank: Super Contributor
timestamp: June 21, 2012, 01:32:41 am
content: It's a cockroft walton right ?1) AC supply please,no bridge rectifier needed2) Depicted is a two stage multiplier, yours looks like a 2-1/2 stage

author: digsys
author_rank: Unknown
timestamp: June 21, 2012, 01:35:06 am
content: Try it this way -The first step charge is conflicting with the DC supply to the regulator, which need a filter cap, 220-1000uF depending on powerrequired. And it still maintains a reference to the +- rails.

author: DaveHardy
author_rank: Regular Contributor
timestamp: June 21, 2012, 02:31:36 am
content: Thanks for the replies guys. I know that you are going to hate me for this answer, but I tapped into a "Home Brew" PSU circuit that I got from a trade and just assumed that everything was chipper. After very close inspection, I realized that It has two transformers in it and the secondaries are wired in a totally unconventional manner - THEY ARE TOTALLY FLOATING!!. This is why I was getting low voltage when referencing ground.The Circuit Works Just Fine and BTW, tapping into the positive output of the bridge as a reference gives it an added boost with fewer parts.Yes, I forgot to put caps before the regulators:)
HC-05 Bluetooth adapter and keyboard - Page 1
Forum section: electronics / projects

author: netdudeuk
author_rank: Frequent Contributor
timestamp: February 10, 2014, 10:18:09 pm
content: HiI bought a Bluetooth keyboard with a view to using it with an HC-05 connected to an Atmega chip.The idea was that the HC-05 would send out the key presses to the micro controller for processing.I've been able to connect to the BT adapter via a soft serial port on the chip and use AT commands to select master mode, set a PIN, scan for devices, see the keyboard's address and name. The problem is, I cannot get AT+PAIR to pair the keyboard with the BT adapter. I see the FAIL message.Am I trying to do the impossible here ?The keyboard pairs ok with my PC and iPad. My phone can see the HC-05.

author: DomesticHacks
author_rank: Regular Contributor
timestamp: February 11, 2014, 09:06:23 am
content: I think the HC-05 only implements the serial protocol and won't work with a keyboard.
HC-05/06 Bluetooth chopup - Page 1
Forum section: electronics / projects

author: Sac
author_rank: Contributor
timestamp: February 22, 2020, 08:13:47 pm
content: Howdy Strangers.Just needing some advice on adding an external antenna on an Hc-05 bluetooth module. The radio field is all smoke and mirrors to me and i don't have a clue.On the HC-05 module the antenna is built into the board. I'm looking at a project that will be in a metal case so i need to get the antenna out so it can breathe in the outside world. Can i get away with mounting a IPX connector on to the PCB antenna and plug in a external antenna to that?I've had a look and can't find a HC-5 with a jack on them from factory ,I see a CC2540 module has them.https://www.aliexpress.com/item/32833007971.html?spm=a2g0s.9042311.0.0.42534c4dIKcxtCChr Snow

author: profdc9
author_rank: Frequent Contributor
timestamp: February 23, 2020, 02:42:22 pm
content: It's not an elegant solution, but I soldered a quarter wave wire onto my HC-05 at the base on the antenna and it seemed to help the range/reception quite a bit. I have done this on other cheap 2.4 GHz wifi dongles as well with a significant improvement in performance. You could probably twist together two thin pieces of magnet wire to make a low impedance twisted pair transmission line and then fan these out to make a dipole. I think a lot of the RF design in these cheap dongles may be intentionally poor to limit the range or just poorly done and so any kind of wire like that is an improvement.
HC-06 Woes - Page 1
Forum section: electronics / projects

author: Tnixsw
author_rank: Contributor
timestamp: October 07, 2025, 06:59:43 am
content: Hi all,I have been using many HC-06 Bluetooth modules for some time (not the breakout boards) and soldered directly to circuit boards they are ok for the projects I use them in There seems to be two types available one without a LED and one with a blue LED fitted to the board although you only get what the dealer has. The ones with the LEDs work fine, but lately I am getting many faulty modules without the LEDs fitted.They program ok using the AT commands and they pair ok to my PC and an external LED works as it should. However, the serial comm link does not appear to work. I know the baud rate is ok, because I can issue new AT commands and get proper responses. If I replace the faulty unit with a new module with a LED fitted, they work every time.It's a long shot, but I was just wondering if anyone else has been experiencing this issue. I am assuming a bad batch has been unleashed and I doubt they get tested.cheersTony

author: thm_w
author_rank: Super Contributor
timestamp: October 09, 2025, 12:47:58 am
content: If its not a settings issue, you can reprogram them, though it looks like a bit of efforthttps://www.martyncurrey.com/hc-06-hc01-comv2-0/https://www.instructables.com/Upgrade-Your-3-Bluetooth-Module-to-Have-HID-Firmwa/

author: Buriedcode
author_rank: Super Contributor
timestamp: October 09, 2025, 03:34:58 am
content: Quote from: Tnixsw on October 07, 2025, 06:59:43 amThe baud for the link (normal) mode isn't necessarily the same for AT mode.I had real trouble getting a HC-06 to work with windows 10 - it seems the drivers for these isn't the most stable, and would sometimes open several com ports of the same name. I ended up having to remove any hint of CSR based drivers and using windows 10's latest. It works, but I ended up switching back to the 'ol HC-05 since it was jsut easier to work with.
Hc05 Bluetooth Restore to default automatically - Page 1
Forum section: electronics / projects

author: binu_ji
author_rank: Newbie
timestamp: October 13, 2022, 10:19:57 am
content: Hii am using HC05 Bluetooth module in one of my product and its running inside the fishing boat.Its a GPS module with HC-05 module. i am using a 5V usb adapter and using B0505S-1WR3 Mornsun 5V to 5V DC-DC Converter for further power isolation.I renamed the module to my product name before shippingThe module works fine and some of them compliant the module renames to HC-05 automatically, that is its Restored to default value.Dont know how it happens, any body have any possible way to prevent it.Binu
HCMOS Oscillator output waveform measurements - Page 1
Forum section: electronics / projects

author: electronx
author_rank: Regular Contributor
timestamp: June 04, 2024, 08:54:14 pm
content: My ASV-50.000MHZ-EJ-T oscillator's datasheet is here .My goal is to measure the oscillator output with an oscilloscope. The ideal square waveform I expect is as follows,my measurement setupHantek MPO6204d 200Mhz probe 1x modeLet's look at the output value according to the information given in the datasheet.High state 0.9 x Vdd0.9 x 3.3V=2.97VLow state max 0.4VOscilloscope measurement max 2.1Vmin 1.23VI also see a triangular wave, not a square waveWhat is the reason of this?Here are the possibilities1. I see the triangle waveform due to reflections (due to impedance equalization).2. The gnd probe of the oscilloscope probe with which I made the measurement forms a huge loop.3. I completely miss things.4. Oscillator output is as it should be.5.My expectation on the oscillator output is wrong6. load capacitance may exceed maximum capacitance (15pF)

author: Benta
author_rank: Super Contributor
timestamp: June 04, 2024, 09:10:19 pm
content: None of the above.But rather that using alligator clips, long wires, unshielded probing etc. at 50 MHz is bound to fail.Great for DC and low frequencies, but that's it.Take an RF 101 course.

author: electronx
author_rank: Regular Contributor
timestamp: June 04, 2024, 09:17:29 pm
content: Even if I change the gnd probe?

author: tggzzz
author_rank: Super Contributor
timestamp: June 04, 2024, 09:46:50 pm
content: What is the risetime of your signal generator?You don't see a triangular waveform, you see an exponential risetime, characteristic of an RC circuit. The C will be determined by the *1 cable's capacitance, maybe 100pF, depending on length. The R will be determined by your signal source.What is the source of "max capacitance 15pF"? If it is the specified load for your source, then a *1 probe will exceed it.Probesalwaysaffect the circuit and the measurement. To understand how to use probes effectively, see the refs athttps://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/

author: Benta
author_rank: Super Contributor
timestamp: June 04, 2024, 09:58:00 pm
content: Quote from: electronx on June 04, 2024, 09:17:29 pmThat's a better approach. Now you just need to fix power supply and decoupling as well.There's a reason that 50 MHz circuits need a fixture (eg, PCB with test points) and not alligator leads from alibaba.

author: mawyatt
author_rank: Super Contributor
timestamp: June 04, 2024, 10:10:56 pm
content: Make sure the probe is set to 10X or is a 10X probe.Best,

author: tggzzz
author_rank: Super Contributor
timestamp: June 04, 2024, 10:28:43 pm
content: Quote from: electronx on June 04, 2024, 09:17:29 pmThat looks like more than changing the gnd probe. It looks like a *10 probe, which will have a tip capacitance of maybe 15pF.
HD video capture with overlay? (Think dashcam stuff) - Page 1
Forum section: electronics / projects

author: Nogginboink
author_rank: Newbie
timestamp: May 06, 2015, 06:56:32 pm
content: I'm curious to know what it would take to develop an HD DVR similar to the dashcam units easily found on AliExpress. I'd like to build a device that would allow me to capture HD video, overlay character text on top of the video, and store an output .mpg file on an SD card.I haven't had much luck finding any chips that would perform these functions. Then again, this entire industry appears to be walled off from hobbyists.Does anyone have any idea what semiconductor parts might be used to build a solution, and how to get hold of these parts from hobbyist-friendly distributors?
HD44 D-Sub-miniature Breakout Board - Page 1
Forum section: electronics / projects

author: Eric Williams
author_rank: Newbie
timestamp: May 02, 2012, 07:17:06 pm
content: I've seen these boards that allow you to access the individual lines of a simple DB9 connection by simply inserting it between two mating connectors. Has anyone ever come across anything like this for DB44HD connectors?
hd44780 With 14-Pins and PCF8574 IO expander did not work - Page 1
Forum section: electronics / projects

author: robby.roboter@gmail.com
author_rank: Newbie
timestamp: September 03, 2024, 09:15:23 am
content: I have multiple displays and most of them workingbut this display have only 14 pinsI attach it like this ignoring last pins 15, 16as it should be led pinscode works fine and i2c address is found with a scannerWhat did I miss?
HDMI 5 port switch detecting LED with Arduino - Page 1
Forum section: electronics / projects

author: Stealthrt
author_rank: Regular Contributor
timestamp: September 04, 2015, 05:51:54 pm
content: Hey all I am wanting to make a project for this HDMI 5 port switch I have. I want to be able, with an Arduino, to detect which of the 5 ports are being used (only 1 can be used at any given time).Without buying 5 of something like this to detect current (which would be ~$30):Would it be possible for me to just purchase one of these and hook up different resistors values to each of the 5 LEDs and use the Arduino's Analog input to detect the voltage to determine which port LED was on?I'm thinking that the standard red led voltage is around 2.0v? And the Android analog input is 5v. If this is possible then what type of values for the resisters for each of the 5 LEDs would be best to use in order to read the difference enough for each with the Arduino's analog input?Example:Code:(com Gnd)--------------|(led1)---/\/\/----\ | |----------------|(led2)---/\/\/-----\ |----|[-] -->to Arduino 5v Pin(led3)---/\/\/------|-------|[+] -->to Arduino Analog Pin(led4)---/\/\/-----/ | -->to Arduino Gnd Pin(led5)---/\/\/----/ |----------------|Or would this be possible without even using the current sensing module?

author: marshallh
author_rank: Unknown
timestamp: September 04, 2015, 08:19:01 pm
content: No need, just wire each port's HPD (hotplug detect) to your 5v tolerant MCU.
HDMI cabling questions - Page 1
Forum section: electronics / projects

author: Andree Henkel
author_rank: Regular Contributor
timestamp: September 12, 2025, 12:16:04 pm
content: I want to misuse HDMI cabling for another purpose.Mechanical consideration tell I got to use HDMI (upright, for Master/Backplane) and Mini-HDMI for Slave Modules.I got some questionsCurrent rating of the Pins is 0.5A, what is to be expected for the wires and what for the shielding foils?So far I understand are the differential pair shields isolated to each othe and also to the connector body, correct?

author: BILLPOD
author_rank: Frequent Contributor
timestamp: September 12, 2025, 01:54:41 pm
content: Good Morning Andree Henkel, I read the cables can handle 1 to 3 Amps. Lots of good info here:https://fpga.mit.edu/6205/_static/F24/default_files/CEC_HDMI_Specification.pdf

author: mtwieg
author_rank: Frequent Contributor
timestamp: September 13, 2025, 12:59:30 pm
content: I have quite a bit of experience using HDMI for general signaling/power delivery (work related, can't say too much). Like other media cables, there's a lot of variability between models and vendors. Very recently one of the cables on our BOM went EOL so we had to find an alternate. We run significant DC current through them, so of course I tested resistance of the 5V and return path, and found some cables were a factor of five higher than others (for the same length). Nothing in the cables' datasheets hinted at this, so it's important to test things yourself. I didn't tear apart the cables to determine why the variation was so great. I'm guessing the ones with lower resistance use the outer braid as a ground return (unclear if this is permitted by the HDMI spec).I didn't actually try to determine the max current at which the cable fails. I would definitely not expect reliable operation at 0.5A. Contact ratings and conductor ratings are totally different things.Quote from: BILLPOD on September 12, 2025, 01:54:41 pmThanks for posting the spec, but Ion't know where you get 1-3 amps from. Definitely not in this document. Here's what it says regarding max current:Quote
hdmi > eDP converter, RTD2556_eDP_1H_R10.1 board - need firmware - Page 1
Forum section: electronics / projects

author: RobertRupa
author_rank: Newbie
timestamp: September 18, 2019, 08:23:24 am
content: Hi,Where i can get firmware for this board on RTD2556. I want to use it with ST50D80218, but im only getting white screen ;/
HDMI Impedance Matching - Page 1
Forum section: electronics / projects

author: electosleepy
author_rank: Contributor
timestamp: April 26, 2016, 04:39:55 pm
content: Hi, I'm trying to impedance match a HDMI signal on the top layer of my PCB. I have used found following values in the attached picture by experimenting with this calculatorhttps://www.eeweb.com/toolbox/edge-coupled-microstrip-impedance/.My original dielectric (FR-4) substrate thickness was 10 mil which meant that I needed to have a 18 mil trace to meet the HDMI 100 ohm differential signal impedance requirement. This trace was too wide and my ideal trace width is 5 mil which reduces the substrate thickness to 2.5 mil. My question is generally how thin are you allowed to make the dielectric substrate layers generally speaking? What tolerances can you generally expect for the dielectric substrate thickness? As the few manufactures that I have looked at only specify overall board thickness.

author: Apollyon25_
author_rank: Regular Contributor
timestamp: April 28, 2016, 02:43:25 am
content: I use Saturn PCB's (www.saturnPCB.com) PCB toolkit for most things. Trace impedance tinkering especially.Our stackup is 8L and top to bottom our dielectric thicknesses are 0.113 PP, 0.12 FR4, 0.221 PP, 0.36 FR4, 0.221 PP, 0.12 FR4, 0.113 PP (in mm; PP = PrePreg)Ask you local/usual PCB fab house what stackup constraints they have.

author: KE5FX
author_rank: Super Contributor
timestamp: April 28, 2016, 03:16:00 am
content: Quote from: electosleepy on April 26, 2016, 04:39:55 pmThat disqualifies them for your application, I'm afraid. Any board house worth doing business with will provide you with their standard stackups for different layer counts.This is what I use for differential traces withSunstone's 6-layer stackup, for instance. Your board house should have a similar page.

author: electosleepy
author_rank: Contributor
timestamp: April 30, 2016, 04:16:16 am
content: Thank you for taking the time out to write a very detailed reply, this has given me a lot to think about, I'll be back when I have done some more research. At the moment I'm in the development phase for a prototype fortunately the HDMI input trace length is under 25mm with no vias per TMDS pair and the HDMI output trace is under 50mm with two vias per TMDS pair.

author: electosleepy
author_rank: Contributor
timestamp: May 06, 2016, 01:11:58 am
content: Is there any simulation software that you guys can recommend? Also currently the vias on the HDMI signal traces go from the top layer to the bottom layer, would it be better to use a buried via?
HDMI Monitor - Page 1
Forum section: electronics / projects

author: Christopher
author_rank: Frequent Contributor
timestamp: March 30, 2014, 04:43:57 pm
content: Hi all,Soon I'll be working on a few projects with some kind of Linux mini-pc like the Pi or Beaglebone.What I am after is a *cheap* HDMI monitor similar to this:A HDMI input is preferred as then I am not tied to a specific system. My requirements:* Cheap (Approx £50-100) & in stock* I can send a purchase order to them (No dodgy ebay Chinese sellers)* HDMI or micro HDMI input* 6-8" in size* Mounting holes, no case.* No whacky PCB buttons. I'll be adding buttons to my own enclosure, thank you very muchSome help would be greatly appreciated!
HDMI Output from Rasp Pi Pico with RS485 Commands - Page 1
Forum section: electronics / projects

author: salihkanber
author_rank: Regular Contributor
timestamp: July 09, 2023, 06:26:10 am
content: Dear all,I have been working on generating images on an HDMI LCD monitor for a while. For this purpose, we have designed a Raspberry Pi Pico module that includes RS485 and HDMI connections. My goal is to send commands via RS485 to Rasp Pi Pico to display different images accordingly on the HDMI monitor.What do you think about this, and have you experienced such a project?

author: MarkS
author_rank: Unknown
timestamp: July 09, 2023, 10:10:18 pm
content: Does it work? Can the Pico even output proper HDMI signals?

author: abeyer
author_rank: Frequent Contributor
timestamp: July 09, 2023, 10:23:29 pm
content: 👀

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 09, 2023, 10:35:39 pm
content: Quote from: MarkS on July 09, 2023, 10:10:18 pmYes, absolutely. Obviously limited to a relatively "low" frequency. (I have seen other projects about this - I think they achieve 250 MHz or something like this, I guess that should give you 640x480 or thereabouts?)With overclocking the chip of course, and clever use of the PIO and both cores.

author: MarkS
author_rank: Unknown
timestamp: July 09, 2023, 10:52:43 pm
content: Quote from: SiliconWizard on July 09, 2023, 10:35:39 pmI would never had guessed! If I were to make a video-based project with the Pico, I would have gone straight to VGA. This opens up doors I didn't know exist!

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 09, 2023, 11:11:30 pm
content: Quote from: MarkS on July 09, 2023, 10:52:43 pmDitto, getting some VGA output on a Pico is something I plan on doing. While getting HDMI working is doable, it's really pushing things here and you're still limited to a relatively low resolution.

author: themadhippy
author_rank: Super Contributor
timestamp: July 09, 2023, 11:27:55 pm
content: Dont stop at vga,add a ps2 keyboard,lob basic on it and relive the 80's home computer erahttps://geoffg.net/picomitevga.html

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 09, 2023, 11:37:29 pm
content: Yes that's pretty cool. Amazing what you can do with this $1 chip.
HDMI scrolling effect at high resolution - any ideas?  - Page 1
Forum section: electronics / projects

author: Ale2.0
author_rank: Contributor
timestamp: April 04, 2020, 09:36:17 pm
content: Hello dear community!I am currently building up a new FPV setup for my drone. For this I also use a HDMI to AV converter which works great at 480p but i get a scrolling like effect (Video, zipped). It gets better if I lay down a finger on the connector but not perfect (only if I truly touch the contacts) .As I have no real clue of the HDMI standard I don't know of I could force 480p by hardware?Fyi the source is a GoPro Hero 7 Black which outputs 1080p if not filming and during filming 480p. As far I have researched there's no way to enforce 480p output.So if someone has an idea how to change this let me know!Thanks beforehand and greetings from SwitzerlandAle

author: amyk
author_rank: Super Contributor
timestamp: April 04, 2020, 09:37:56 pm
content: Loss of vertical sync.

author: Ale2.0
author_rank: Contributor
timestamp: April 04, 2020, 09:39:40 pm
content: Yeah I thought this is a thing is there any way to fix this? Thanks anyway!

author: Ale2.0
author_rank: Contributor
timestamp: April 04, 2020, 10:17:38 pm
content: I now also reflowed some pins at the connector but it did not helpActually if I press on the contacts I can get it nearly perfect but iI Don't know what I am adding. Maybe some resistance, capacitance? I tried connecting some pins with a 1Mohm resistor which only had an effect on one pin which has a solid 3.2V on it according to my oscilloscope. I also reflowed this pin. No clue what's going on...Edit: I also tried shielding everything with some tinfoil. Had no effect.

author: Ale2.0
author_rank: Contributor
timestamp: April 05, 2020, 08:25:46 pm
content: UPDATE:As touching the pins was the only indicator for help I tried different resistors to short some pins. Dirty but seems to be a way. I could identify one pin which is affecting it. Oscilloscope tells me it's a 3.2v stable. Anyway may investigate more later. If I connect it with one MOhm to the pin beside it, it's getting better. The lower I get with the resistance the better it gets. At a value of 510 Ohms it almost disappeared.I think I'll solder this resistor down but to be honest it's not really satisfying me as I have no clue what it's affecting etc. I think 510 is still a relatively high resistor, especially with only 3.2 V applied.What do you think about this? Is it somehow making sense to anyone?Picture: The two pins I am talking of marked with black points. It's a micro HDMI, but I can't get any Theory around with the pinout either.Thanks for any explanation
HDMI source to DP sink - Page 1
Forum section: electronics / projects

author: Hofi
author_rank: Newbie
timestamp: April 26, 2023, 06:35:34 am
content: Hi,i need to convert a hdmi video source in a display port signal on a board level. Are there any translation ICs available? DP to HDMI is no Problem but for the other way round i can hardly find anyting...

author: wraper
author_rank: Unknown
timestamp: April 26, 2023, 06:45:57 am
content: There are. However it issue is that they are hard to buy and datasheets are not openly available. Most likely you'll need to pay thousands of $ for HDMI licensing before any manufacturer of such IC will want to talk with you.

author: Hofi
author_rank: Newbie
timestamp: April 26, 2023, 07:02:12 am
content: This is no problem because i am planning to use this for a commercial device

author: wraper
author_rank: Unknown
timestamp: April 26, 2023, 07:05:39 am
content: You could get a few different adapters like thishttps://www.techly.com/hdmitm-to-displayport-converter-adapter-with-usb-4k-60hz.htmland look what's inside to get more clue about who makes them.

author: Someone
author_rank: Super Contributor
timestamp: April 26, 2023, 07:53:53 am
content: Quote from: Hofi on April 26, 2023, 07:02:12 amTalk to your rep at Avnet.

author: Hofi
author_rank: Newbie
timestamp: April 26, 2023, 11:00:25 am
content: Quote from: Someone on April 26, 2023, 07:53:53 amThank you for the hint. I have already planned a meeting with them today for another topic, so i can ask them.I also found this thing:https://www.kinet-ic.com/uploads/STDP2600-03b_Datasheet_Brief.pdfSeems to be exactly what i am looking for. Eval board is on its way from DigiKey.
HDMI terminations - Page 1
Forum section: electronics / projects

author: wanton789
author_rank: Newbie
timestamp: August 21, 2013, 10:47:14 pm
content: I hesitated to open another post so quickly, but this is a different topic and figured it was better than tagging onto theother one. The other post will get bumped down.This question has to do with terminations on an HDMI line - specifically the fourTDMS (Transition-minimized differential signaling)lines:1. clock2. data 03. data 14. data 2This post looks long, but if you follow the instructions closely it should be quick and easy to navigate. Thanks in advance.I am using aPericom PI3HDMI101. This IC is a "HDMI/DVI Buffer + I2C Buffer for Source Applications".I will simply be using it as a switch or relay for some automation of testing by controlling the Output Enable. It will sit on a PCB between two HDMI connectors.On thevery first pageof thisapplication note, the first two paragraphs talk about different termination resistors for the TDMS signals. Using an input pin (RX_SENSE), one can toggle the termination on the CLOCK lines between 50 ohms and 250k ohms.The datasheet says it is possible to interchange the clock and data lines in which ever way the designer likes if necessary (e.g. for layout reasons).My question is:Why does the clock have options for termination resistors?If the designer decides to interchange lines, the RX_SENSE pin should be toggled to set the termination at 50 ohms (so that they match the data lines - data lines have 50 ohm pull ups by default).If it is possible to interchange the lines and maintain functional operation - again, why does the clock have different termination options?Further, refer to the2nd half of page 2onthis datasheetfor the PI3HDMI101.NOTE: there are two versions of this chip - the PI3HDMI101 and PI3HDMI101B<---They are nearly the exact same as far as pin out and operation.2nd half of page 2further illustrates the operation of the RX_SENSE pin. It again mentions that the lines can be interchanged.. blah blah..Scroll down to page 5for an example schematic of the terminations.I believe these terminations are all internal. But then check out that firstapplication noteagain,looking at page 2 and 3 - the two Source Application Schematics.-The first schematic iswithoutRX_SENSE function - RX_SENSE is tied to VDD - setting termination to 50 ohms-The second schematic iswithRX_SENSE function - RX_SENSE is... going to a voltage divider tied to the output of the CLK_OUT--also CLK_OUT+ is terminated via 20k to GND, which itwas notin the first schematic-CLK_IN+ is 1.5k to gnd, which itWASin the first schematic-CLK_IN- is 22k to gnd, which itwasnot in the first schematicFinally, in thedatasheet for theBversion -(see page 2, the TMDS Receiver Block paragraph)....it says the termination is done automatically.And now I'm lost. If I had slightly more knowledge on terminations and t line theory...
HDMI to CVBS?  - Page 1
Forum section: electronics / projects

author: jasons520
author_rank: Newbie
timestamp: May 10, 2018, 12:06:58 am
content: Hi everyone,I was wondering if anyone has had any luck building a HDMI to CVBS (Pal or NTSC) converter?There seems to be hundreds of them for sale for cheap (Below $100), but i was wondering if anyone knows what kind of Integrated circuit these things would be using to make them so cheap? HDMI seems very intricate and fast to me, but you can convert it to an analog signal for below $100?Is there black magic inside one of these?Has anyone ever pulled one apart?Regards, Jason

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 10, 2018, 03:16:24 am
content: They use small, cheap ASICs.

author: Scrts
author_rank: Frequent Contributor
timestamp: May 10, 2018, 12:55:22 pm
content: Quote from: jasons520 on May 10, 2018, 12:06:58 amYou should check Renesas (former Intersil -> former Techwell) TWxxxx series parts. As well as Analog Devices HDMI receivers and CVBS encoders.
HDMI to Displayport conversion, how? - Page 1
Forum section: electronics / projects

author: dzseki
author_rank: Frequent Contributor
timestamp: December 18, 2020, 12:28:22 pm
content: I have a Displayport to VGA converter here that is based on the STDP3100 IC from ST. Now I don't have any source with Displayport output, only HDMI. Is there any easy way to convert a HDMI signal to be accepted by this converter?I know there are direct HDMI->VGA converters, I am mostly just cuirous if I can make use of the converter what I already have?

author: wraper
author_rank: Unknown
timestamp: December 18, 2020, 12:52:23 pm
content: You need active HDMI to VGA converter. Your DP to VGA converter is active as well but inputs completely different signal. If you have DVI output, there may be additional pins (DVI-I) for analog signal and then you can use passive adaptor, however modern graphics cards dropped that and only have DVI-D.

author: bson
author_rank: Unknown
timestamp: December 19, 2020, 07:29:25 pm
content: I don't think there's anything in HDMI that can't be passed through to DisplayPort - the latter can handle all that the former can. LPCM audio etc. It's the electrical signaling and negotiation that differs. In fact, googling seems to suggest there's no shortage of small HDMI-to-DP adapters. (HDMI in DP out dominates, but the other direction is I believe not much more complicated.)