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?


1 Answer 1


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)

  • \$\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

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