1
\$\begingroup\$

I'm having issues with a board with USB-C not being powered. I've simplified everything back to basics to try confirm my understanding. I have a USB-C breakout board, I've wired 2 10k's in parallel (didn't have any 5k1 to hand, but is within 10% so should be ok), wired between CC1 and Ground and CC2 and Ground. Plugged into my laptop, laptop dock and two different USB C chargers (generic one and this Spigen), I don't get 5V on VBUS on any of them.

What am I missing?

\$\endgroup\$

1 Answer 1

Reset to default
3
\$\begingroup\$

You need to follow the USB C standard if you want to see power.

You followed the standard for a receptacle, but you are working with a plug.

You have a plug, which means you need to wire a single CC pin (not both) to ground via a 5.1k resistor (20% or better). Your 2 x 10k in parrallel will work fine here)

\$\endgroup\$
4
  • \$\begingroup\$ Thanks @Ferrybig, that's kicked the breakout board into action. I have the receptacle version on order. The issue I was trying to resolve is my board, with receptacle, fitted with the two 5k1 resistors, I see three spikes at 5V then it settles to 0.4V but I'll verify my setup with the new breakout then create a new question with the relevant details. \$\endgroup\$
    – epac-tom
    Nov 16, 2022 at 14:08
  • \$\begingroup\$ @epac-tom If you have 2 of those plug breakout boards, wire them directly like an USB C to C cable (eg connect A1,B1,A12 for GND, connect A4, B4, A9, B9 for VBUS, A6 for D+, A7 for D- and A5 for CC). That way you can probe each signal pin \$\endgroup\$
    – Ferrybig
    Nov 16, 2022 at 14:26
  • \$\begingroup\$ So I hooked up the two breakout boards, as suggested (well I didn't bother with all the grounds and VBus, and I'm not running firmware has enabled the USB so D+ and D- we also skipped) and it works. So is the issue is now narrowed down to one cable (of 3 so I'm ordering a few more to test with), this is the culprit Startech USB31CC50CM, which I believe should work like any other I am testing (I believe the rest are USB 2.0 though). \$\endgroup\$
    – epac-tom
    Nov 17, 2022 at 15:25
  • \$\begingroup\$ One common cause for a device only powering with USB C2C 2.0 cables is yet another violation of the USB C standard, instead of using 2 5.1K resistors, they join both CC lines together and use a single 5.1K resistor. Your USB 3.0 cable contains a a resistor and a chip in the cable pulling the normally unused VCONN line strongly to ground. This was also an issue with the raspberry PI 4: bartlomiej-klocek.medium.com/… \$\endgroup\$
    – Ferrybig
    Nov 18, 2022 at 8:14

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.