5v to USB-C Cable, 56k resistor? Confused on Power Negotiation

LIGISTX · November 8, 2021

I am sure this has been answered many times over in many places, but I am struggling to find an answer as all my results more or less end up in custom USB cables for keyboards... not what I am after.

I am a bit confused on the USB C standard and am having trouble making a cable for my needs. Its a very simple need: 12v to 5v converter in my car (this part works, no problem...), with 5v going to a gopro USB-C port to power it without the need for battery. I have it simply wired up so the ground goes to ground, and +v goes to my 5v source. It powers fine, everything "works" as expected, until I use my GoPro USB-C to 3.5mm mic port and USB-C for charging adapter. When I use this, I get no audio from my mic. When I use the same adapter with my Anker PD cable batter bank, the gopro works as intended and I get audio over the 3.5mm input.

Clearly I am missing some handshake logic so the gopro doesn't assume the USB-C cable I have coming from my car is "something that it isn't" (what I am not sure, maybe it thinks its a USB C mic? Maybe it thinks its a computer? I have no idea). I just need to be able to plug my 5v USB-C cable into my gopro and have it work as intended, which is clearly possible as my Anker battery bank does this just fine.

What am I missing here?

LIGISTX · November 9, 2021

18 hours ago, James Evens said:

Do you use with the anker powerbank the same DIY cable?

Yes, the cable is an Anker Cable, the DIY solution is all custom wired with a USB C end on it, I can't plug it into anything as its directly soldered to my 12v to 5v converter.

I have decided to just go the "easy" route and replace my 12 to 5v converter with a female cigarette lighter, and got an anker cigarette lighter that I will plug USB-C into.