Does anyone make an affordable USB-C power sink tester? - Page 1
Forum section: electronics / testgear

author: 5U4GB
author_rank: Super Contributor
timestamp: November 07, 2023, 11:55:58 am
content: Given the ever-increasing amount of stuff that's powered via USB-C connectors and the annoying percentage of it that gets it wrong since it was only ever tested with a USB-A to USB-C cable, does anyone know of an affordable tester that'll check at least the pulldown resistors on a USB-C sink? I'm currently doing it with a USB breakout board and a multimeter, but having a quick go/no go check would make things much easier. Something a bit more sophisticated that also monitors USB PD comms and reports what's going on there would be icing on the cake. While there are a million devices that test everything related to the source and/or the cable, I haven't been able to find anything under three to four figures for the sink.

author: dougg
author_rank: Regular Contributor
timestamp: November 08, 2023, 07:56:25 am
content: The "USB Cable Checker" fromwww.treedix.comis pretty cheap and will test just about any USB to USB cable plus it can test lightning to USB cables. However it just tests continuity. For testing USB pull-downs a multi-meter could be used with the CC1, CC2 and Gnd solder covered pads near the edge of the checker's board. I bought the version with the perspex cover. Was a bit disappointed that there is only one piece of perspex that covers the front. The provided bolts include 4mm plastic standoffs for the exposed back.

author: 5U4GB
author_rank: Super Contributor
timestamp: November 08, 2023, 12:24:24 pm
content: Yeah, that's what I'm using at the moment but it's a bit of a hassle to set up and read values on pins each time I want to test something, thus my hope to find something like the LimePulse cable checker on Tindie that just shows the overall status, but for USB-C sinks rather than cables or sources.

author: 5U4GB
author_rank: Super Contributor
timestamp: November 17, 2023, 11:44:04 am
content: Just found another one, a USD ~400 device that omits the pulldowns on the CC lines, sigh. Anyone with a Tindie account want to do a USB-C sink fixer-upper with a male connector on one side, female on the other, and 5.1k pulldowns in between?

author: 5U4GB
author_rank: Super Contributor
timestamp: February 29, 2024, 11:15:44 am
content: And another one, only just released, the BliKVM which requires that you use a USB-A to USB-C cable because they've messed up the USB-C power signalling on the device. It'd be really useful to have something like this...

author: artag
author_rank: Super Contributor
timestamp: February 29, 2024, 08:42:39 pm
content: I've seen a USB C PD debugger tool advertised only very recently.Maybe crowd supply or kickstarter ?edit:found it !https://www.crowdsupply.com/elektrothing/spark-analyzerAlso note that there's a sigrok PD protocol disassembler. just needs a breakout and capture.Re the adapter - found this on tindie - more expensive and functional than need be but at least it's ready to add the resistorshttps://www.tindie.com/products/treble/usb-cthrough/This might also do it if one of the female connectors were replaced with a male. However the pinning on USBC connectors varies widely and sometimes includes commoning which may make it hard to find a compatible part.https://www.tindie.com/products/crowbartech/usb-c-ondom/

author: artag
author_rank: Super Contributor
timestamp: February 29, 2024, 09:13:31 pm
content: Quote from: dougg on November 08, 2023, 07:56:25 amI havehttps://www.tindie.com/products/petl/usb-c-cable-tester-c2c-caberqu/Costs more and does less but I guess it's smaller !

author: cosmicray
author_rank: Frequent Contributor
timestamp: February 29, 2024, 09:41:54 pm
content: My impression (subject to correction) is that if the USB-C isonlysupplying 5V, the the comms are optional. The comms are for establishing a contract with the PD on what voltage to send, or to sayI'm sorry Dave, I can't do that. If the comms don't respond, then 5V is all you get.

author: 5U4GB
author_rank: Super Contributor
timestamp: February 29, 2024, 11:49:41 pm
content: Quote from: artag on February 29, 2024, 08:42:39 pmThe problem with all of those is that they test the wrong end of the connection, the upstream device (PD power source) or cable, not the downstream device, the thing that's misconfigured to request the wrong amounts or levels of power. There's a million things that test the upstream end but I haven't been able to find anything that tests the downstream end. The USB-CThrough looks like it's a start, but at least for the CC stuff you can do the same with a USB-C breakout board and a multimeter, which is what I've been using so far. Unfortunately this doesn't handle broken PD negotiation.What would be useful to have, not just for me but for all of the countless organisations creating broken USB-C devices, is a tester that you can plug your device into that reports something like "the device is asking for 5V@500mA max" or "the CC resistors are installed wrong" or similar.

author: thm_w
author_rank: Super Contributor
timestamp: March 01, 2024, 01:00:16 am
content: Could you use a supply that requires the pulldown resistors to function? Then have an inline monitor if needed to measure voltage and current.

author: mwb1100
author_rank: Frequent Contributor
timestamp: March 01, 2024, 06:30:16 am
content: If $190 counts as affordable, see if theCypress CY4500 EZ-PD Protocol Analyzerwill do what you need. Some of the features:- decoding USB Power Delivery packets in real time on the CC lines- Decodes PD 2.0, PD 3.0, Extended messages and USB4 messages- CC line Voltages, VBUS Voltage and Current monitoring- Graphical view of the CC lines, VBUS Voltage and CurrentOnly monitors the PD protocol - it can't modify or spoof the protocol.There's also theGoogle Twinkie projectand various forks/improvements (such asTwonkie).features:- Sniffing USB Power Delivery traffic on both Control Channel lines (CC1/CC2)- Transparent interposer on a USB Type-C connection- Monitoring VBUS and VCONN voltages and currents (Twonky supports USB PD 3.1 EPR voltages up to 48V, Google's Twinkie only SPR voltages up to 20V)- Injecting PD packets on CC1 or CC2- Putting Rd/Rp/Ra resistors on CC1 or CC2Google the terms to find out more.There's someone selling assembled Twonkie devices for 112 EUR here:https://shop.3mdeb.com/shop/open-source-hardware/twonkie-usb-c-sniffer/Disclaimer: I have used exactly none of these devices

author: 5U4GB
author_rank: Super Contributor
timestamp: March 01, 2024, 10:08:44 am
content: Ah, the magic search term seems to be "usb-c pd sniffer" rather than (say) "usb-c analyzer". Unfortunately all the stuff from an initial search has been quite expensive, or discontinued, or hard to use (e.g. supported under one particular release of one particular OS), but I'll keep looking. ThePlugable TKEYlooked the most promising but it's EOL, then there's theFresh-Twinkiewhich is DIY hardware, and a bunch of other stuff is non-USB-C.

author: mwb1100
author_rank: Frequent Contributor
timestamp: March 01, 2024, 08:29:17 pm
content: Quote from: 5U4GB on March 01, 2024, 10:08:44 amMy understanding is that the Pluggable TKEY was pretty much a faithful implementation of Google's Twinkie. The Fresh-Twinkie is a Google Twinkie with changes to make it easier for a DYIer to build.The only place I found pre-assembled Twinkie-like devices is the the Twonkie I posted the link to. If it works well, it seems the price (112 EUR) isn't a bad ask. Maybe I'll pick one up - I have a bunch of the various USB "power meter" gizmos, but it would be interesting to be able to look a bit more under the hood. I have no real need (other than curiosity), but that's the same for my small collection of multimeters and oscilloscopes.

author: 5U4GB
author_rank: Super Contributor
timestamp: March 18, 2024, 10:42:43 am
content: So it looks like there is such a device (and then some) that's readily available, it's the STSTM32G071B-DISCOwhich, alongside a huge amount of other functionality, provides a "spy" mode in which it sits between two USB-C devices andreports power profiles and information.Or at least that's what the docs seem to imply, has anyone every played with one of these?

author: 5U4GB
author_rank: Super Contributor
timestamp: September 24, 2025, 12:48:54 am
content: And something like this has finally turned up, the QianLi iBridge A3 available for a few tens of dollars from your favourite crapvendor. It reports the status of all the downstream USB-C pins including the CC resistors and similar. It's self-powered so you just plug it in and turn it on, you can also use it as an inline tester for power delivery and it'll report the status of D+/- and CC1/2 as it's powering the device. Unfortunately there are no docs so it's unclear what it's reporting in the non-power-delivery state, a bunch of values between 0 and 1. I've only just got it so I'll have to try and dig through the USB-C specs to see if there's a clue there on how to interpret the values.

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 24, 2025, 01:15:37 am
content: There's this:https://manuals.plus/asin/B0FJ7F9ZCDNot sure how useful that will be to you, but I'm sure you'll rectify it.Thanks,Josh

author: thm_w
author_rank: Super Contributor
timestamp: September 24, 2025, 02:24:05 am
content: Quote from: 5U4GB on September 24, 2025, 12:48:54 amIts injecting voltage and telling you what voltage is being read back. Normal data pin might be 0.5 (diode drop?), if its not seeing any impedance its OL (ok or not, depends on the pin), if its shorted to Gnd (reads 0.01) then there is a problem with the port.Nothing to do with USBC spec.There is also a YCS version:https://www.aliexpress.com/item/1005009412793815.htmland Relife version:https://www.aliexpress.com/item/1005008146627785.html

author: 5U4GB
author_rank: Super Contributor
timestamp: September 24, 2025, 10:20:14 am
content: Quote from: thm_w on September 24, 2025, 02:24:05 amRight, that makes sense, thanks.I'd seen some of the others, given their similarity to the Qianli and the how prolific the Qianli's are I assumed they were the ur-type for the design.

author: DaneLaw
author_rank: Frequent Contributor
timestamp: September 25, 2025, 03:36:43 am
content: Quote from: thm_w on September 24, 2025, 02:24:05 amPurchased one of those 20 $ tail-back testers around a year back..A purchase mainly driven by curiosity.As far as I could tell, this handful of different models that were on the market back then' all seemed to be based around the same inner hardware, just with different enclosures.Though haven't tried the PC software or tested what kind of accuracy they are synonymous with.* Its ability to also act as a standard Type-C USB PD meter V/A & W are not good, its accuracy is way off (could just be my unit).

author: 5U4GB
author_rank: Super Contributor
timestamp: September 25, 2025, 03:50:28 am
content: Interesting, several of the photos show readings outside the 0-1 range that are usually shown. I wonder if that's a YCS thing or it's just coincidence that stock images used by sellers always seem to show 0-1.

author: thm_w
author_rank: Super Contributor
timestamp: September 25, 2025, 09:28:27 pm
content: Quote from: 5U4GB on September 25, 2025, 03:50:28 amThe readings from that power bank are definitely a bit odd, I wouldn't expect much to be connected up other than vbus/cc1/cc2/etc. Unless it has some kind of data connection.Since you have a the USBC breakout board you can test it on that.

author: DaneLaw
author_rank: Frequent Contributor
timestamp: September 25, 2025, 09:56:37 pm
content: It's primarily on the second socket, it shows high reading in the 2... That one is a Type-C PD3.0 100W socket, while its lower on the other Type-C, jwhich is a PD3.1 140W.Its a powerbank, so likely limited how many of these 24pins that are used for backlog inner circuitry, and are active..On a 100W PD TypeC socket like the one above, I would guess around 10-14 of the 24 pins are active, the rest I would guess, are not used, as no data/Alt-mode is required..Confidence is not that high in these tail-plug units, as the accuracy on the "powermeter" interface seems of... Could look like that power-interface has been dropped on some of the other models?Example of the *notice in post #18 above.Fx Charging the powerbank, the correlated values don't add up.// A brief search shows even their own promotion video seems to simulate that behaviorhttps://www.facebook.com/watch/?v=958609672856327)Even the promotional pictures of Qianli and YCS seem to have this lack of correlation between the charge V/A & W values, or the decimal point that seems misplaced.https://ae01.alicdn.com/kf/S0bd63a7af1fd4e19a4fed35ff7ba22c8f.jpg?width=750&height=9761&hash=10511

author: 5U4GB
author_rank: Super Contributor
timestamp: September 26, 2025, 04:13:47 am
content: Quote from: DaneLaw on September 25, 2025, 09:56:37 pmCould it be that they're correcting for advertising issues like in 5S2P batteries that are variously sold as 18V, 19V, and 21V depending on which brand it is? That doesn't explain the DP but it could explain the non-Euclidean maths.