hybridfree/eevblog-posts huggingface dataset:
usb lipo charger - Page 1
Forum section: electronics / beginners

author: kaiDev
author_rank: Newbie
timestamp: January 11, 2014, 01:42:27 pm
content: The projectMy friend has a system for warming his ski boots, and a solar powered portable usb charger battery pack, and when he is out on a trip (multiple days) he wants to charge the ski boot warmer with the solar battery.The electronicsThe ski boot warmer batteries aretherm-ic ic950http://www.therm-ic.com/ThermicSoles/Packs/Smartpack-IC-950.htmlthey are promoted as litium-ion batteries and the charger's output is 8.4v so i reckon they are dual cell batteries.I do not know the make or model of the solar usb battery but it's usb so it must be 5v and between 500-1000mA.My planI know charging litium batteries can be tricky. So i have found a charging circuit that i want to usehttp://www.ti.com/lit/an/slua023/slua023.pdfto charge a dual cell battery it requiers 9-13Vdc inputMy problemThe missing link is a DC to DC converter that can boost 5v to 9-13v. I have searched around and have found the datasheet for LT1302http://cds.linear.com/docs/en/datasheet/lt1302.pdfwith an application example for 2v to 12v converter. I have duplicated it in LT Spice to test and connected it to a 5v battery and it gives a 12v output. So far so good (i think).But the application example dose say 120mA so i dont know what happens if the solar usb battery can deliver more than 120mA and i dont know how to test it with output load in LT Spice so i don't know if it wil actualy produce 12v when connected to the charging circuit. I have tested it with various resistor values between OUT and GND but i do not know if that is a good test or not.Can some one help me in figuring out if the converter will work or if any one has a better idea. i would appreciate sugestions.LT Spice file:http://kaidev.net/charger/voltage%20converter.asc(right click > save as)

author: peter.mitchell
author_rank: Super Contributor
timestamp: January 11, 2014, 03:52:55 pm
content: Depending on the Solar usb Battery, it may actually be easier to just modify it to provide a higher output voltage to charge the pack.However, also, depending on the solar usb battery and the power usage of the "therm-ic ic950", this may be completely impractical (if it draws too much power, or if the solar battery pack doesn't store enough charge or if the solar pack does not charge fast enough ect)

author: kaiDev
author_rank: Newbie
timestamp: January 11, 2014, 03:59:04 pm
content: I agree that it would bee easyer to modify the solar usb battery but that would make it imposible to chare any thing else like a phone or any thing built to charge from usb. I was hoping to make a circuit that connects with a mini or micro usb.
"USB memory" and Arduino on same serial port? - Page 1
Forum section: electronics / beginners

author: MysteriousH
author_rank: Newbie
timestamp: May 01, 2022, 07:46:50 pm
content: Yes, "'USB memory' and Arduino on same serial port?" might be the wrong question to ask, but thats why am asking, since I am not sure what to actually ask...So, what is it I actually want to do? Well the basic idea is to build a datalogger (i.e. a Arduino with an amplifier circuit to read temperature/strain etc.), which when connected to a PC launches an executable from its memory to display the readings (with some additional features). My limited understanding of the issue is that the memory and the datalogger would not be able to share the same serial port and an usb hub circuit would be needed, or is there some nice searchterm to Google? Doing something like alternating between the sources, loading the executable into RAM and then switching to the Arduino serial or something similiar?Or should I just read up a bit on serial comms?Thank you in advance, for any searchterms, or other advice you may provide

author: tooki
author_rank: Super Contributor
timestamp: May 01, 2022, 08:04:53 pm
content: USB storage doesn’t use serial communications.Basically, what you want is some kind of microcontroller that can both access a storage medium of some kindand present it to the computer as a USB Mass Storage device.(The latter is a requirement if you want to be able to launch a program from the storage.)Apparently, this kind of thing has been done before:https://hackaday.com/2019/05/29/drag-and-drop-files-on-select-arduino-boards/But it seems it won’t work with every type of Arduino, and is quite difficult:https://forum.arduino.cc/t/arduino-as-mass-storage-device/872958

author: MysteriousH
author_rank: Newbie
timestamp: May 01, 2022, 08:19:15 pm
content: Thank you for the reply, nice links and an clear indication that I should read up at bit more the topic of USB interfacing in generalIf having the microcontroller access and present the memory as a "USB Mass Storage device" doesn't work out, the stupid solution would just be to make/add a USB hub so it appears as two separate devices?ignore this, I'll just test it myself to see if it works
USB Noise filtering - Page 1
Forum section: electronics / beginners

author: Sythen
author_rank: Contributor
timestamp: October 03, 2013, 03:23:15 am
content: Morning all!Me and a friend are working on an SDR project around the RTL-SDR Dongles, and we have come up with a possible method of filtering noise from the 5V line, but we are in dispute around what capacitor/s to use to do the job.Here is the board we came up with to do the job, its main intention was to distribute power to 2 devices at the same time from one USB port, but as we were coming up with the design, we decided to add filtering.The intention was to use a 10uF Electrolytic Cap.Any insight into what caps to use, or if the design needs tweaking would be greatly appreciated.Copies of the design files are available if you want a copy.Thanks!

author: jorisbeurden
author_rank: Newbie
timestamp: October 03, 2013, 08:37:56 am
content: Do you only want to use the USB connection as a voltage source or is the PCB also required to transport data?

author: Sythen
author_rank: Contributor
timestamp: October 03, 2013, 09:40:45 am
content: @jorisbeurden: The board will carry data, but only to one device, it will however be providing power to more than 1 device.@mojo-chan: Yeah, that was another option we are looking at right now, its likely that ill add that feature in on a later revision of the board.
USB output from audio device (SPIDF/I2S) - Page 1
Forum section: electronics / beginners

author: Toney
author_rank: Contributor
timestamp: August 28, 2020, 08:39:53 pm
content: Hi,I have an audio device that has audio format in I2S or SPIDF. What kind of ready made solutions exist to convert this format to USB output capable of recording the audio device to a computer? Musical instruments and effects often contain such USB capability, and I want to know how they accomplish the task.

author: oPossum
author_rank: Super Contributor
timestamp: August 28, 2020, 11:38:39 pm
content: TI has several chips that can do this. PCM2902C, PCM2903C, PCM2906C, and possibly others.

author: Toney
author_rank: Contributor
timestamp: August 29, 2020, 12:30:15 am
content: Quote from: oPossum on August 28, 2020, 11:38:39 pmAnything higher fidelity than 48kHz/16 bit? And what about the physical outputs?

author: oPossum
author_rank: Super Contributor
timestamp: August 29, 2020, 05:12:49 am
content: XMOS and CMedia are two other commonly used USB audio chips. Using them is quite a bit more complicated than the TI solutions.https://www.cmedia.com.tw/products/USB20_HIGH_SPEEDhttps://www.xmos.ai/software/usb-audio
USB port connections - Page 1
Forum section: electronics / beginners

author: RyanT
author_rank: Contributor
timestamp: March 25, 2018, 12:57:01 am
content: I bought a micro USB port that I intended to use to supply 5V to a project (no data). It was part of a larger order and I didn't check the pin dimensions as thoroughly as I should have, and so I have a relatively expensive USB port that I have no easy way of connecting to my prototype project. Or any project for that matter.Samtec SPM-05-S-B-RA-PF datasheet (PDF).It's a right angle through hole panel mount component, but I think would pretty much require a custom PCB. Is there a connector (or individual pin connectors) that might work with that? I didn't have any luck searching.If it comes down to it, I might try tinning the pins and soldering wires to them, but due to their tiny size, close separation, and surrounding plastic, there's not a lot to work with. I don't need the thing to be easily removable later, I just need a decent connection on the power pins.I guess a third option would be to simply order a more suitable connector, but I'm feeling a bit stubborn at the moment.

author: RyanT
author_rank: Contributor
timestamp: March 25, 2018, 01:09:43 am
content: Aye, only reason I went with mini was because I already had some cables that were the perfect length for my application. It would not be plugged/unplugged very many times at all... maybe a dozen times over the entire lifespan of the product.

author: Raj
author_rank: Frequent Contributor
timestamp: March 26, 2018, 06:01:35 pm
content: For me, it's always the plug that fails, never seen a failing socket for usb mini...But there must be some tests published on the internet somewhere
USB Power Inquiry - Page 1
Forum section: electronics / beginners

author: Krowez
author_rank: Newbie
timestamp: March 18, 2016, 01:00:33 am
content: I have been playing with my raspberry Pi 2 ( more than a xmbc media center that is ) as of late since the release of the Pi 3.I have found that my usb external hard drive that I use with it has drawn the pi to a near stop due to it's power draw from the bus.I have remedied this with a powered hub but was thinking since I have a half dozen cables & power adapters lying about that i might be able to skip the hub all together and just power the drive from that rather than pulling from the Pi.My Plan is to take the primary USB cable and cut the reb and black wires so it doesn't provide power from the pi's USB bus.Then take the second cable and connect red to red and black to black and have it powered from a usb wall adapter that has the proper power support.Is there anything that might cause problems as the pi's bus not being able to acknowledge that hard drive's existence without the power connected ?I have done some similar off the cuff things before and have ruined other projects in the past.thanks for your input in advance.

author: Krowez
author_rank: Newbie
timestamp: March 18, 2016, 01:22:26 am
content: Quote from: blueskull on March 18, 2016, 01:14:25 amI am confused with that statement.I understand the cut the red part, but should I splice in the black cable from the new power cable ?

author: PeteH
author_rank: Unknown
timestamp: March 18, 2016, 01:38:33 am
content: You should splice the black as you've stated.The raspberry pi needs to be ground referenced to the hard drive... The wall adaptor should be isolated if it is a reputable manufacturer which breaks any ground loop. USB has a somewhat limited common mode range even though it's differential signalling.

author: Krowez
author_rank: Newbie
timestamp: March 18, 2016, 02:07:49 am
content: the power adapter i have is a cheap brand but honestly provides the full 5v 1a that is says it does.but thanks for the input i shall put this to the test here shortly.
USB Power regulator "stabilizer?" - Page 1
Forum section: electronics / beginners

author: ElektroQuark
author_rank: Unknown
timestamp: November 06, 2013, 07:15:01 am
content: Hello:I'm working in a little project with a microcontroller powered from USB.As USB power can be from 4.5 to 5.5V (more or less).Can you suggest a simple buck-boost regulator for 5V?Any other solution will be welcome.Iñigo.

author: dr_p
author_rank: Frequent Contributor
timestamp: November 06, 2013, 07:22:05 am
content: can't you run the micro at 3.3 from an LDO?

author: ElektroQuark
author_rank: Unknown
timestamp: November 06, 2013, 07:35:37 am
content: No, it runs at 5V.

author: AndyC_772
author_rank: Super Contributor
timestamp: November 06, 2013, 07:47:15 am
content: What's the specified operating range in the data sheet? It might well work over, say, 4.5 - 5.5V and you don't have a problem.If you really need a regulator that will deliver a fixed 5.0V output over that input range, I'd look at a SEPIC controller. Head on over towww.linear.com, download LTSPICE, and have fun picking out and simulating a controller IC.

author: mariush
author_rank: Super Contributor
timestamp: November 06, 2013, 07:47:44 am
content: most microcontrollers will work just fine with as low as 4.5valso in reality rarely the usb voltage will be THAT low. Usually you'll only see as low as 4.7-4.8v due to voltage drop on the wires.I would just use a very low vdrop linear regulator set to 5v, to simply smooth voltages above 5v. There are Microchip ldos that have 50mV drop or something like that so even if you get 4.8v at the input, the 5v ldo will output about 4.75v which should still be good enough for your microcontroller.if you really want 5v, use a buck/boost regulator that can work in sepic mode. Higher frequency regulators will require smaller inductors and will work just fine with ceramic capacitors.. see LT1307 or LT1308 for example(but they're a bit expensive being linear parts)

author: sleemanj
author_rank: Super Contributor
timestamp: November 06, 2013, 09:58:25 am
content: Search eBay for LM2577 Buck-Boost, cost is less than $10 USD, they work well.

author: ElektroQuark
author_rank: Unknown
timestamp: November 06, 2013, 10:25:00 am
content: Thank you for all those suggestions.I will look at them.
USB power requirements - Page 1
Forum section: electronics / beginners

author: Matt-
author_rank: Newbie
timestamp: August 04, 2020, 07:48:30 am
content: Hi!I have a project, being powered off ~25v DC, with two regulated rails -- a 12v and a 5v. I'd like to have a single USB port for charging devices, but am confused by the way in which USB devices negotiate power delivery and battery charging. It's my understanding that higher levels of USB negotiate voltage and power delivery, but I'm unclear on basic power supply.Can I hook the 5v power rail to a USB breakout board, and let the remote device manage battery charging and power consumption at 5v, or do I need something 'smarter' to regulate the negotiation and power delivery to the device?Many thanks in advance.

author: sleemanj
author_rank: Super Contributor
timestamp: August 04, 2020, 08:34:12 am
content: For plain old 5v USB, yes connect 5v directly to the USB socket, and short the data pins togethor will work for most things (Android).If iPhone then you might need to use combination of resistors on the data pins to convince it to draw more than 500mA, google it for details.

author: Matt-
author_rank: Newbie
timestamp: August 04, 2020, 08:51:33 am
content: Awesome. Thanks very much!
USB QC3.0 for charging a 43.6 Wh battery / Help on step up XL6019 module - Page 1
Forum section: electronics / beginners

author: downloaders
author_rank: Contributor
timestamp: June 24, 2018, 06:16:52 pm
content: I would like to charge a drone battery from a QC3.0 chargerThe battery is pretty big and I know it will take a couple of hours, but since everybody in the drone scene says it can't be done, I wanted to give it a go.To the specs:- The battery is a DJI Mavic pro with a High Voltage 3S Lipo (3.8V) 3830 mAh 43.6 Wh (Starts charging at exactly 13.05V)- The charger I will be using outputs 1.5A at 12V (no 20V on this one)- I wanted to use a XL6019 step up module to to step up the 12V to 13.1Vhttps://www.ebay.com/itm/XL6019-DC-DC-Step-Up-Boost-Power-Supply-Module-Adjustable-Power-Converter-Board/201819767941?hash=item2efd654485:g:zOoAAOSwfVpYo83UAs for the most difficult part which is to make the QC3.0 charger output 12V I was thinking of this:http://blog.rnix.de/12v-from-a-usb-powerbank/Or since that last one is pretty time consuming, this:https://www.banggood.com/JUWEI-Qualcomm-QC2_0-QC3_0-Automatic-Voltage-Current-LCD-Tester-p-1110201.htmlSince the charger can output 1.5A at 12V I would expect to charge 3830mah in at most 4 hours, right?Also, is the XL6019 the best choice for this?

author: firehopper
author_rank: Frequent Contributor
timestamp: June 25, 2018, 07:58:08 am
content: your biggest issue I think is the endpoint voltage of the lipo battery when fully charged lipos top out at 4.2 volt per cell. high voltage ones might top out at 4.35 volts per cell so 3 cells times 4.35 = 13.05 volts (instead of 12.6 volts for normal lipo) you should read up on how to charge a lipo, if you get it wrong, you could burn down your house. they use a constant current and constant voltage controllers.. to keep things within safe limits.

author: CustomEngineerer
author_rank: Frequent Contributor
timestamp: June 26, 2018, 03:29:02 am
content: Quote from: downloaders on June 24, 2018, 06:16:52 pmFrom that linkQuote

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: June 26, 2018, 11:01:19 pm
content: Here is some theory to support on you're quest for the charger :http://blog.deconinck.info/post/2017/08/09/Turning-a-Quick-Charge-3.0-charger-into-a-variable-voltage-power-supplySource code is also on Github:https://github.com/vdeconinck/QC3Control
USB - RS485 DMX interface problem - Page 1
Forum section: electronics / beginners

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: February 12, 2016, 09:30:03 am
content: I posted a thread in Repair section a few weeks ago concerning three 36 LED RGB stage spotlights that I had acquired for repair.I have three working LED spot lights now, and decided to have a play with the DMX interface just out of interest. I found the cheapest USB to RS485 interface on eBay and ordered it (I didn't want to spend too much time getting involved in knocking up an interface...)This was the item:http://www.ebay.com.au/itm/USB-to-RS485-Converter-Module-for-Computer-USB-RS485-Port-PL2303-Drive-S-/191736124887?I struggled to sort out a driver for the interface but finally got a PL2303 driver that 'worked'.The chip on the interface is a Prolific PL2303 (or clone) with a MAX485.I downloaded copies of QLC+ and a couple of other lighting control programs suggested on the previous thread and installed them on an old workshop XP laptop.I cannot get any of the programs to recognise the interface, and the only theory that I have is that they will only work with FTDI chips.The PL2303 is recognised by name by '232Analyzer' so I assume that the interface is working.Has anyone any experience of this issue.Is my theory correct, so do I need to knock up/purchase an interface with an FTDI chip ?Regards, BT
USB selector via transitors  - Page 1
Forum section: electronics / beginners

author: andrewlapham
author_rank: Contributor
timestamp: May 03, 2020, 01:27:42 pm
content: Ive been playing around with a cheap car stereo i got from aliexpress and was thinking of expanding on its stock USB playback. The idea is to use the existing buttons on the headunit that select radio memory, cut their traces and feed them into an arduino that selects from multiple USB drives hidden inside the case. This way i can have a fast way of changing through my music genres and styles.I was hoping this could be achieved by just using simple transistors on the positive rail of each USB disk?So all the disk drives would be wired into the back of the USB port and the transitors would be breaking the connection to each 5v rail until one of them is pulled high via the microcontroller.Would this work?

author: Manul
author_rank: Super Contributor
timestamp: May 03, 2020, 01:41:55 pm
content: No, because ESD diodes will be effectively shorting the data lines if you have unpowered devices on the bus.

author: andrewlapham
author_rank: Contributor
timestamp: May 03, 2020, 02:28:52 pm
content: What if i connected 5v and GND straight through and only swiched the D+,D-?

author: OwO
author_rank: Super Contributor
timestamp: May 03, 2020, 02:39:02 pm
content: You have to switch the D+ and D- pins but you might be able to get away with leaving everything powered on. RF switches might do the job but beware that unselected ports get shorted to ground.

author: langwadt
author_rank: Super Contributor
timestamp: May 03, 2020, 02:43:56 pm
content: Quote from: OwO on May 03, 2020, 02:39:02 pmthat depends on what kind of rf switch

author: Manul
author_rank: Super Contributor
timestamp: May 03, 2020, 02:51:42 pm
content: Out of interest I measured my SanDisk ultra usb 3.0. Data lines clamp at 0.8V while injecting 1mA of current. So, no, you can not switch just +5.

author: janoc
author_rank: Super Contributor
timestamp: May 03, 2020, 02:56:55 pm
content: Why not use something that is actually designed for the purpose?https://eu.mouser.com/Semiconductors/Switch-ICs/USB-Switch-ICs/_/N-7590j?P=1ynzmedE.g. ISL54225 (2:1 multiplexer) or MAX4899AE (4:1 multiplexer) sound just like what you need.If you want more than 4 devices I would rather start thinking about a different solution - implement a mass storage device using a microcontroller that will permit you to swap between music collections (I guess the idea is to swap between them quickly without going through the clunky radio menu) and will pull data from one or multiple memory sticks/cards attached via a regular USB hub.Definitely a better solution than trying to physically switch the USB lines (which could end up even corrupting your USB sticks if you switch at the wrong moment).

author: andrewlapham
author_rank: Contributor
timestamp: May 04, 2020, 01:05:15 am
content: Ok ive completely shifted gears and gone with an RPI with a voice assistant that pulls music from a local source.
USB sniffer - Page 1
Forum section: electronics / beginners

author: Jane
author_rank: Frequent Contributor
timestamp: July 31, 2015, 10:29:14 am
content: Can anyone recommend a good USB and I2C sniffer?I have USB - I2C bridge ( developement board) and would like to check the data both on USB side and I2C side.Or how do YOU check the data on USB that a program sends to?

author: 6thimage
author_rank: Regular Contributor
timestamp: July 31, 2015, 02:58:22 pm
content: Hardware USB sniffers tend to be very expensive, I have, in the past, used a virtual machine (vmware) and got it to log the USB traffic. But either way, you will end up with lots of data that will take quite a while to process (USB is really quite complicated).Just capturing the I2C is probably going to be easier - I haven't come across many I2C sniffers, as for most uses a logic analyser (or digital oscilloscope) is more than adequate. The only advantage of a sniffer would be collecting data over a longer period. As far as recommending logic analysers, it really depends on your needs - the open bench logic sniffer is really cheap, but has only a short memory, many people like the Saleae products for a low cost logic analyser, but they aren't cheap by any means. If you give more information on your needs, it might be easier for people to make recommendations.

author: Matje
author_rank: Regular Contributor
timestamp: July 31, 2015, 10:34:54 pm
content: Quote from: Jane on July 31, 2015, 10:29:14 amEthereal/Wireshark running on Linux can capture and show USB data, provided the "usbmon" kernel module is loaded.
USB Supercapacitor - Page 1
Forum section: electronics / beginners

author: Mp3
author_rank: Frequent Contributor
timestamp: March 03, 2022, 02:22:24 pm
content: Please hear out my idea and let me know if it will work before I get started.- A USB powered device (ADC) is briefly power cycled twice during a PC reset.- The device is used with an ADUM3160 based isolator for protection of the PC.- It would be ideal to keep the unit powered during reboot.Of course one possibility is power from separate 5V, but i don't like that idea. The unit only draws ~35mA so it should be easy to keep on for under a minute during reboot.I thought- make a circuit with ADUM3160 feeding into supercapacitor 5.5V-schottky diode between usb from host and ADUM3160- have this device between PC and USB device (ADC)

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 03, 2022, 03:25:40 pm
content: What's doing DC isolation?Supercap is fine, as long as ESR is low enough (i.e. memory backup types probably aren't enough), and it's supplied from a resistor or current source to limit charging current. So like, the load might be supplied from diodes to wired-OR it between cap and direct input, and input into current limiter into cap. So as soon as input is removed, the load seamlessly transfers to the cap.Looks like a couple F should be enough for a minute uptime, even without special features (like a boost to maintain supply as the cap drains).Some calculators here:https://www.seventransistorlabs.com/Calc/PSHoldUp.htmlTim

author: NorthernWing
author_rank: Contributor
timestamp: March 04, 2022, 01:48:53 pm
content: Also, just be aware that there is a maximum inrush limit in the USB spec (50uC, or 10uF of capacitance), so you'll have to limit the charging current going into the capacitor to within the 500mA USB spec past that - don't just put it across the +5V VBUS. Doesn't take much, you could probably make this as simple as a resistor and a diode.
usb swicth schematic review request - Page 1
Forum section: electronics / beginners

author: mastupristi
author_rank: Newbie
timestamp: June 03, 2025, 04:35:22 pm
content: Hi.I would like to ask you for a review of this schematicIt should serve as a switch for USB power between two USB-C-USB-A ports.The switch is controlled by an STM32F042F4P6 microcontroller. There is another USB-C port from which power is taken for the microcontroller and all the logic. On this USB the micro will implement a USB CDC (virtual serial) with which it is possible to control the switch from a PC.There is also a pushbutton (on reset) and a slide switch (on boot0) for the micro to enter DFU mode for field update. There are footprints for SWD connector and crystal. I will try to get the micro to work in crystal-less mode.Do you see any errors in the pin assignment of the micro?Do you think a ferrite bead is also needed on the GND of the USB connectors?Do you have any other suggestions?best regardsMax
USB Test Gizmo - Page 1
Forum section: electronics / beginners

author: WaveyDipole
author_rank: Frequent Contributor
timestamp: November 23, 2017, 12:32:28 pm
content: I recently purchased a couple of these cheap USB testers. I saw them being used on a couple of YouTube videos and thought htey might be useful. For the price I did not expect them to be accurate. Although the voltage reading seem to be correct to within 0.1v or so, the current reading for a plugged in device is very inaccurate. Both behave in pretty much the same way and do not show a current reading for any load much below 200mA. According to my PSU (which is accurate against my 4.5 digit DMM to within one count) the LED array draws 58mA and the SDR radio 98mA, yet both show a reading of 0.00A on both of these testers. The dummy load is rated 1A (reads 5.004ohms), but shows a reading of only 0.88mA on one gizmo and 0.82 on the other. I would have thought is should be within a count or two (I could live with maybe 4 or 5) of 1.00A.Is this quite usual for these testers?Why are they so inaccurate on current readings?Why do they sometimes show no current reading at all?(Please note that on this charger being used, the top port seems to have a slightly higher voltage reading than the remaining ones).

author: frogblender
author_rank: Regular Contributor
timestamp: February 07, 2018, 06:06:36 am
content: Yeah, they suck.As you've found, the current measurement below about 500mA is horrible. The exact reason escapes me (dang brain)... but it is a common issue with "low-side" resistor current sensing - basically, at low currents, the opamp's inputs and output are all ground or very near ground. And the mfg was too stingy to create a negative supply rail, so the opamp's negative power pin is ground too. And the opamp is pole-axed by it's finite common mode input range.Once the current rises, the sense resistor voltage rises, and the opamp inputs and output rise away from the ground pin.... and all is good.

author: phil from seattle
author_rank: Super Contributor
timestamp: February 07, 2018, 06:57:34 am
content: I have one of those (around here somewhere) that I bought from AdaFruit a while ago. It only shows 2 decimal places on the current but within those bounds, it appears to correct. Voltage is pretty close to my other DMMs.

author: paulca
author_rank: Super Contributor
timestamp: February 07, 2018, 07:58:49 am
content: I use the little grey one with the oLed for "indicative" readings. I'm not really interested in accuracy or characterising, just "How much is the device pulling, roughly"
USB to Sata chip. - Page 1
Forum section: electronics / beginners

author: PepiHax
author_rank: Newbie
timestamp: December 30, 2018, 02:40:31 pm
content: Hello.A little back story.So i have one of these TS-809 Chassis from QNAP, this Chassis has a repaired board from a TS-509 in it, with a E7400 intel core two duo processor.This NAS is currently running Ubuntu server and works great.However as the processor is an older one, it uses a lot of power compared to some of the newer arm processors. Especially the Raspberry Pi or the ROCK64.I would therefore like to make a breakout board, that would fit inside the chassic, which can control and power the harddrives.Which is where my question comes from, as i have seen these USB to Sata breakout adapters on Ebay and other such sites, and they generally go for anywhere from 5 bucks and up.So i have been looking on Digikey and Mouser for chips that can be used as a USB to Sata bridge, and i have found some like the TUSB9261, JMS578 and the ASM1351.The TUSB9261 seems like massive overkill as it has an arm core inbuild.And the last two seems impossible to buy, even for their newer versions.( Do note that any raid functionally can be done within the OS )And last the question, does anybody know of any of these USB to Sata bridges which isnt impossible to get? or would it be easier to program a microcontroller to do this?I am more or less hoping that someone can point me in the right direction.Anyways happy new year.

author: mvs
author_rank: Frequent Contributor
timestamp: December 30, 2018, 04:20:25 pm
content: Quote from: PepiHax on December 30, 2018, 02:40:31 pmYou can buy JMS578 in low quantities at aliexpress

author: bitwelder
author_rank: Super Contributor
timestamp: January 02, 2019, 01:13:07 pm
content: If what you are after is powering off the HDDs when not needed, shouldn't it be that possible from software, running an appropriate 'hdparm' command to set the HDD idle time?
USB to serial bridge - Page 1
Forum section: electronics / beginners

author: IconicPCB
author_rank: Super Contributor
timestamp: January 16, 2016, 04:25:21 am
content: Other than the solutions offered by Atmel, FTDI ( FT232R ) and WCH CH340 families of chips what else might be worth consideration?

author: MLXXXp
author_rank: Frequent Contributor
timestamp: January 17, 2016, 01:02:34 am
content: https://www.eevblog.com/forum/reviews/alternatives-to-ftdi-usb-to-uart-converter/
Usb to serial rs 485 ACPi adapter - Page 1
Forum section: electronics / beginners

author: OLopezNYC
author_rank: Newbie
timestamp: March 22, 2013, 07:14:53 pm
content: I am currently working on a USB TO Serial converter. please look at schematic enclosed of the RS232 to 485 converter that I am using currently. My question is, can I make this cable USB instead of db9 serial. The Cable is used to interface with Elevator PLC controllers but my issue is that those cables are not usb. Is there any way I can do this?The second image shows the configuration another configuration that also works for us using a B&B 485CON Converter. I can not make it work with USB to serial converter because I need to set the port to ACPI Communications at my device manager port driver settings. I hope I'm in the right place for this kind of stuff.

author: somlioy
author_rank: Regular Contributor
timestamp: March 23, 2013, 08:06:48 pm
content: Couldthis (page 27)be something?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 23, 2013, 08:17:45 pm
content: Why reinvent the wheel - there are plenty of perfectly good USB-485 adapters out there (and a few rubbish ones)Easysync do a good range :http://www.easysync-ltd.com/category/145/usb-to-rs485.html
USB to UART -- CH341A based -- Cannot connect -- Win 11 - Page 1
Forum section: electronics / beginners

author: PinheadBE
author_rank: Regular Contributor
timestamp: June 05, 2023, 04:40:51 pm
content: Hi,I just bought an USB to Serial adapter based on the CH341A chip.The exact model is this one:http://www.chinalctech.com/cpzx/Programmer/Serial_Module/2019/0124/266.htmlI installed the drivers (http://www.mediafire.com/file/r9yjxqp7k753jei/LC-TTL-CH341A_EN.zip/file), Rebooted my computer, checked if the drivers were installed correctly (which was the case, see screenshot with the phrase meaning "The device is functioning normally")Then, I try to access it with Termite, but I cannot connect to any serial port: nothing appears in the drop down list (second screenshot)What did I wrong ?Is there another terminal program I could try ?Any help is welcome.

author: RAPo
author_rank: Super Contributor
timestamp: June 05, 2023, 04:50:39 pm
content: Press Winkey+R, and the device manager should start.Check if there is an entry in the com-ports section.

author: PinheadBE
author_rank: Regular Contributor
timestamp: June 05, 2023, 05:38:44 pm
content: Is it this ?I have not the COM ports section, but the driver is well installed

author: PinheadBE
author_rank: Regular Contributor
timestamp: June 05, 2023, 10:41:51 pm
content: Does anyone have a Win11 and successfully used this USB-to-serial tool ?I am planning to send it back as defective, but then, what other USB-to-serial adapter could I use (based on which chip ?)

author: DavidAlfa
author_rank: Super Contributor
timestamp: June 05, 2023, 11:59:21 pm
content: The Ch341 has a pin to set the working mode, uart or SPI/I2C/EPP, that board has a jumper for it, must be in the wrong mode, check this picture:Also try the official driver:http://www.wch-ic.com/downloads/CH341SER_EXE.html

author: PinheadBE
author_rank: Regular Contributor
timestamp: June 06, 2023, 11:48:41 am
content: Thanks DavidAlfa !It works in UART mode (And Termite communicates with it without any problem), this will already be of great help for me.But in I²C/SPI mode, in the list of peripherals, it appears now as "Unknown device" (with the official driver you mentionned)I tried the "Uninstalling/Reboot/Reinstall/Reboot/Plug the device in" sequence, but still not OK in I²C/SPI mode.Any idea ?Is there a specific driver for that mode ?

author: DavidAlfa
author_rank: Super Contributor
timestamp: June 06, 2023, 12:24:58 pm
content: It's a different driver! Should use both.
usb to uart confusion - Page 1
Forum section: electronics / beginners

author: m3vuv
author_rank: Super Contributor
timestamp: September 03, 2021, 09:21:10 am
content: Hi all,i have a smart 13s bms,it comunicates to my phone via a bt modual,there is pc software available as well for it,however this requires you to buy a uart modual from then,i already have one from another bms, the cable from the bt modual had gnd,tx,rx and vbus connectionsthe wires from my uart modual has only 3 wires,i assume it uses the same wire for rx and tx,hence only 3 wires,is this likley correct?,i want to connect the bms to the pc using what i already have,should i just find v+ and gnd and link the tx and rx wires and try it?,tia.

author: Vovk_Z
author_rank: Super Contributor
timestamp: September 03, 2021, 01:50:55 pm
content: I guess you have to connect GND, TX, RX to make a connection.

author: m3vuv
author_rank: Super Contributor
timestamp: September 03, 2021, 02:15:08 pm
content: what about the vcc?

author: Vovk_Z
author_rank: Super Contributor
timestamp: September 03, 2021, 06:52:10 pm
content: You have to consider available and needed voltages.
USB to USB bridge - Page 1
Forum section: electronics / beginners

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: September 29, 2016, 04:14:22 pm
content: What would it entail for a power supply of a PIC microcontroller based USB to USB bridge.I am a bit unsure about the power supply section.Basically it would be bus powered, the circuit has 2 uC's and these 2 are connected via a uart.Each uC would be connected to a computer.Each uC has a LDO regulator for itself my question is how to make the grounds common.Would i need it to be optocoupled UART interface, or just short out the USB negative of both PC's.Your comments would be highly appreciated.

author: Ian.M
author_rank: Super Contributor
timestamp: September 29, 2016, 04:25:06 pm
content: If you direct couple them and one end's USB is plugged in and the other isn't you have the situation where one MCU is trying to power the other via the idle (high) level of its UART TX pin and the unpowered MCU's input protection diodes. This can result in the other MCU failing to initialise properly when its USB is plugged inThis means you have to add extra circuits to shut off TXD if the other MCU isn't powered. If you optocouple them, you don't get that problem + it no longer matters if thre is any ground potential difference between the PCs,

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: September 29, 2016, 05:08:52 pm
content: Quote from: Ian.M on September 29, 2016, 04:25:06 pmIf I understand you correctly. Power from TX of uc1 would flow into RX of uC2 and then forward bias the top input protection diode and feed into VDD of uC2. This would cause excessing current draw from TX of uC1 and might damage that pin. Did I get you right?

author: Wilksey
author_rank: Super Contributor
timestamp: September 29, 2016, 05:26:25 pm
content: Essentially when the USB is plugged in it gets power then it will try to enumerate, I think what Ian is saying, is that if you only plug one end of bridge in, it will pass power through to the 2nd PIC via the pull ups, so when you plug the 2nd PIC's USB into the computer it will already be "powered" and will not enumerate. Using optocouplers will eliminate this issue as they will be isolated.

author: Ian.M
author_rank: Super Contributor
timestamp: September 29, 2016, 05:30:59 pm
content: Not just risk of damage to the pins, but it may provide enough voltage to the core for it to to get in an unexpected state where it fails to come out of reset or comes out of reset with SFR values different to its normal power on defaults. To a large extent it can be mitigated by enabling BOR on both MCUs and putting 1K resistors in series with the serial data lines, but that may reduce the max baud rate.

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: September 29, 2016, 06:06:16 pm
content: Ian.M / WilskyThese are some really profound understandings...Have some opto's lying around will check it out...
USB to UUT isolation - Page 1
Forum section: electronics / beginners

author: NivagSwerdna
author_rank: Super Contributor
timestamp: June 13, 2018, 08:58:12 am
content: I'm embarking on a gadget that on one side is connected to a PC via a FTDI chip etc and on the other side is connected to a UUT which is a vintage microprocessor board with its own power supply.One side of the circuit is 3V3 whilst the other is 5V derived from the UUT. I'm planning some kind of TI voltage level translation between the two.But that got me to thinking... can I really connect the GND together between the 3V3 and the 5V side? The 3V3 side is relative to PC ground; the 5V side is relative to UUT ground?(This is for my poor man's Fluke 9010a project)Thanks in advance

author: NivagSwerdna
author_rank: Super Contributor
timestamp: June 13, 2018, 09:41:24 am
content: Looking at the original Fluke it appears that the Power Supply is derived from mains and that the different power signals are derived from various secondaries on the transformer so it is not ground referenced.I guess my scenario applies to all test gear that has a PC on one side but a UUT on the other

author: Ian.M
author_rank: Super Contributor
timestamp: June 13, 2018, 11:05:51 am
content: For many applications it isn't a problem to have a common ground shared with the PC, but a common ground is undesirable for test equipment due to the risk of ground loops. You can easily optoisolate the FTDI chip on its I/O pin side, with an isolated DC-DC converter fed by USB Vbus to power the isolated section.For logic level conversion look at 74LVC1T45 or 2T45 buffers. They support partial power down operation so if you power the DUT side from the DUT, they'll tristate all their outputs if either the DUT is powered off or the USB interface is powered down or disconnected. Powering from the DUT also auto-sets the logic level. Add 50mA polyfuses for robustness.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: June 13, 2018, 11:17:49 am
content: Thanks. I was just looking at Murata CRE1 as a 5V:5V isolated supply, looks feasible.For the USB data it is differential... do I really need to opto isolate it?

author: Ian.M
author_rank: Super Contributor
timestamp: June 13, 2018, 11:23:05 am
content: USB isn't pure differential - it uses single ended signalling for framing - and has poor tolerance for ground offsets.*DONT* isolate the USB side of the FTDI chip - that's a royal PITA to do properly, and even if you use a dedicated USB isolator chipset it makes it impossible to support USB speed negotiation or to support USB speeds faster than 12 Mbit/s. Its far easier to isolate the FTDI chip's serial or parallel I/O side.
USB torche - Page 1
Forum section: electronics / beginners

author: IQ12345
author_rank: Newbie
timestamp: October 18, 2024, 01:19:25 pm
content: Good Morning Guys,I’m hoping you can help me out, I’m a woman at the end of my tether.I have been give the task of redesigning a circuit for a torch. As thecomponents are slightly too close.. I have attached a copy of the way students solder the copper strip-board . The new board is slightly wider allowing for less errors, we hope. It’s not a rectangle anymore, as you see by the photo.For some reason the Red LED just stays on like a beacon of failure.I’m not sure if I need to move the resistor around the switch or move the switch.Is my capacitor charging? The torch should charge and come on when the push to make is pressed.I have sent an image of the nearest I have got to a working prototype.Unfortunately the torch only works when it is in the USB socket, and the light goes off when I push the push to make switch.I need the torch to come on when the bus to make is pressed and out of the charger.Rant over! Hellllllp

author: Old Printer
author_rank: Frequent Contributor
timestamp: October 18, 2024, 02:17:57 pm
content: You need to add a picture of the other side of your circuit board so we can see your actual connections.

author: ataradov
author_rank: Super Contributor
timestamp: October 18, 2024, 02:18:57 pm
content: Neither of your pictures shows schematic or any of the component connections. It is literally impossible to tell for sure what may be wrong.Based on the components, I would guess it it charges the super cap though the diode and then the button connects the cap to the LED. The best guess here, assuming no gross assembly errors, is that you used the wrong pins on the button. The button has two pairs of pins that are internally shorted and the press shorts those pairs.

author: wasedadoc
author_rank: Super Contributor
timestamp: October 18, 2024, 02:48:32 pm
content: If you don't have a multimeter (Ohms range) to check which pins of that type switch to use, my experience is that using either of the two pairs of diagonally opposite ones will always work.

author: jm_araujo
author_rank: Regular Contributor
timestamp: October 18, 2024, 02:53:00 pm
content: My guess would be the switch is rotated 90º, the "original" assembly the switch terminals seem to be in the top/bottom, and in the new wider board they are left/right.

author: Gyro
author_rank: Super Contributor
timestamp: October 18, 2024, 05:05:05 pm
content: I hate to say it, but the idea of pushing the end of the stripboard into USB sockets is a terrible idea, it's going to ruin them. The thickness is wrong and the kids will snap the internal plastic tab of the socket, which will get very expensive (in IT equipment or whatever).EDIT: On a more positive note, as the supercap is being charged to 5V, using a (much more efficient) White LED at much lower current would probably give longer run time.
USB trace impedance - Page 1
Forum section: electronics / beginners

author: mandor
author_rank: Regular Contributor
timestamp: January 06, 2025, 10:18:36 am
content: Hello.Working on a keyboard and want to have usb hub and ports on each side of the keyboard so want to run usb signals on 2-layer board.trying to get traces right for usb 2.0 and I've read it should be 90ohm differential impedance.KicadallaboutcircuitsdigikeyjlcpcbEither I'm doing something wrong or they are all giving a different result?

author: Terry Bites
author_rank: Super Contributor
timestamp: January 28, 2025, 09:25:27 pm
content: https://resources.altium.com/p/routing-requirements-usb-20-2-layer-pcb
USB Type-C: capacitors between CC1/CC2 and GND - Page 1
Forum section: electronics / beginners

author: aix
author_rank: Regular Contributor
timestamp: December 25, 2019, 01:29:14 pm
content: I'm looking at the schematic of a breakout board forFUSB302(Programmable USB Type-C Controller with PD).The schematic (attached) has 470pF caps between the CC1/CC2 lines and ground.The official breakout board (https://www.onsemi.com/pub/Collateral/EVBUM2509-D.PDF,page 3) also has caps, only 200pF.I can't seem to find any docs about the purpose of those caps. Would appreciate if someone could explain why they're needed.(I'm designing an FUSB302-based USB-PD sink, for my own amusement/education, and am trying to figure out whether I should include these caps and how to choose them.)

author: mvs
author_rank: Frequent Contributor
timestamp: December 26, 2019, 01:15:06 pm
content: This caps are needed to comply with USB PD specification (BMC cReceiver capacitance 200-600pF). According to Datasheet of FUSB302, cReceiver capacitance is just 50pF typ, so there is room for additional cap and/or TVS protection diode.

author: aix
author_rank: Regular Contributor
timestamp: December 26, 2019, 11:04:52 pm
content: Thanks for this. Now that I know what to look for, I found this note that future readers might find useful:https://www.onsemi.com/pub/Collateral/AN-5086-D.PDF(ON semi AN-5086/D: USB Type-C, CC Pin Design Considerations)
USB Type-C - PCB layout - Page 1
Forum section: electronics / beginners

author: Tantalum
author_rank: Regular Contributor
timestamp: May 03, 2019, 04:25:59 pm
content: HelloI'm designing a PCB of an USB device, and I'm realizing that this USB-C is really a mess.Is there somewhere a kiCAD PCB layout I would only need to copy from?It should include:- SMD USB-C connector (no through hole)- USB 3 + 2 Mux,- CC Controller,- ESD ProtectionThank you

author: LapTop006
author_rank: Unknown
timestamp: May 04, 2019, 01:26:50 pm
content: Quote from: Tantalum on May 03, 2019, 04:25:59 pmAt least a few years ago when I was playing in this space while the pinout for the connector pins was fairly standard, there wasn't any standards for the actual connectors, you'll likely need to make your own footprint.