Does anyone make an affordable USB-C power sink tester?

[5U4GB]

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.

[dougg]

The "USB Cable Checker" from www.treedix.com is 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.

[5U4GB]

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.

[5U4GB]

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?

[5U4GB]

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...

[artag]

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-analyzer

Also 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 resistors
https://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/

[artag]

The "USB Cable Checker" from www.treedix.com is pretty cheap

I have https://www.tindie.com/products/petl/usb-c-cable-tester-c2c-caberqu/
Costs more and does less but I guess it's smaller !

[cosmicray]

My impression (subject to correction) is that if the USB-C is only supplying 5V, the the comms are optional. The comms are for establishing a contract with the PD on what voltage to send, or to say I'm sorry Dave, I can't do that. If the comms don't respond, then 5V is all you get.

[5U4GB]

I've seen a USB C PD debugger tool advertised only very recently.

The 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.

[thm_w]

Could you use a supply that requires the pulldown resistors to function? Then have an inline monitor if needed to measure voltage and current.

[mwb1100]

If $190 counts as affordable, see if the Cypress CY4500 EZ-PD Protocol Analyzer will 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 Current

Only monitors the PD protocol - it can't modify or spoof the protocol.

There's also the Google Twinkie project and various forks/improvements (such as Twonkie).

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 CC2

Google 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

[5U4GB]

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.  The Plugable TKEY looked the most promising but it's EOL, then there's the Fresh-Twinkie which is DIY hardware, and a bunch of other stuff is non-USB-C.

[mwb1100]

he Plugable TKEY looked the most promising but it's EOL, then there's the Fresh-Twinkie which is DIY hardware

My 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.

[5U4GB]

So it looks like there is such a device (and then some) that's readily available, it's the ST STM32G071B-DISCO which, alongside a huge amount of other functionality, provides a "spy" mode in which it sits between two USB-C devices and reports power profiles and information.

Or at least that's what the docs seem to imply, has anyone every played with one of these?