USB-C Confusion - 5v source to USB-C

Thread Starter

LIGISTX

Joined Nov 7, 2021
4
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?
 

Yaakov

Joined Jan 27, 2019
3,967
Welcome to AAC.

USB C is very complicated. You are far better off buying a 12V to 5V supply designed with all the necessary handshaking of the standard which will accommodate all of the cases you might encounter.

There are modules of various sorts for PD (Power Delivery) as opposed to the “PD” in the standard that means “Portable Device” (very confusing to read) that you might use but there are so many car adapters you can get cheap(ish), I would just do that.
 

geekoftheweek

Joined Oct 6, 2013
736
I don't know if it's the same with USB C, but usually you would short D+ and D- together at the charger to designate it as a charger. As already mentioned buying a charger would be easier, but I have been down this road myself. A pair of panel mount USB A socket and a converter tucked up under the dash made things look nice.
 

Yaakov

Joined Jan 27, 2019
3,967
I don't know if it's the same with USB C, but usually you would short D+ and D- together at the charger to designate it as a charger. As already mentioned buying a charger would be easier, but I have been down this road myself. A pair of panel mount USB A socket and a converter tucked up under the dash made things look nice.
USB C uses various specific resistances across the data lines to identify different types of devices. It also has active negotiation which uses either I2C or something like it, I am not sure of the specific of that.
 

Thread Starter

LIGISTX

Joined Nov 7, 2021
4
Welcome to AAC.

USB C is very complicated. You are far better off buying a 12V to 5V supply designed with all the necessary handshaking of the standard which will accommodate all of the cases you might encounter.

There are modules of various sorts for PD (Power Delivery) as opposed to the “PD” in the standard that means “Portable Device” (very confusing to read) that you might use but there are so many car adapters you can get cheap(ish), I would just do that.
Yea, it’s certainly complicated… I had it wired with a USB micro B cable and cut that end up and spliced in a USB C, clearly it’s not that simple :/.

Do you happen to know of a12 to 5v supply that would work? Ideally I’d remove my current converter and replace it with a new one.
I don't know if it's the same with USB C, but usually you would short D+ and D- together at the charger to designate it as a charger. As already mentioned buying a charger would be easier, but I have been down this road myself. A pair of panel mount USB A socket and a converter tucked up under the dash made things look nice.
USB A female socket? Then use a USB A to C cable? Is that what you are doing with success?

Which Go-Pro ?
A battery eliminator on the Hero 2 is 4V and small adapter board also can have additional filtering.
Its a hero 9, but I had the same issue with my 5. My 9 has overheating issues, which is pretty lame… but with the battery removed it 1) produces less heat as the battery isn’t creating heat and 2) gives the GoPro a large cavity to help dissipate heat.

I could just use my battery bank, but I am looking for a more permanent power solution that I don’t need to think about charging as my car is used as a track car, one less thing to think about charging or plugging in is always a plus. Thanks for all the help, sounds like one of these ideas will likely get me there.
 

Papabravo

Joined Feb 24, 2006
17,573
USB C uses various specific resistances across the data lines to identify different types of devices. It also has active negotiation which uses either I2C or something like it, I am not sure of the specific of that.
USB uses USB to negotiate. I would think that might be kind of obvious...Captain. Unless the dilithium crystals are disintegrating.
 
Last edited:

Yaakov

Joined Jan 27, 2019
3,967
USB uses USB to negotiate. I would think that might be kind of obvious...Captain. Unless the dilithium crystals are disintegrating.
Actually, it turns out I had skipped sections in a document and ended up conflating negotiation on the PHY layer with
I2C-Over-AUX capabilities (which is actually part of Display Port). Sorry.
 

Papabravo

Joined Feb 24, 2006
17,573
Actually, it turns out I had skipped sections in a document and ended up conflating negotiation on the PHY layer with
I2C-Over-AUX capabilities (which is actually part of Display Port). Sorry.
That's OK. It's a fairly minor slip and you might only know about if you actually had to implement it at some point.
 
USB A female socket? Then use a USB A to C cable? Is that what you are doing with success?
I kind of slipped... I haven't done A to C quite like you are. It is possible the A to C adapter would help in that it would handle the pins and such to set your GoPro to look like a slave device instead of OTG (if it actually has that functionality). It may have something to do with that. Other than that I really don't know. USB isn't something I've really studied much.
 

cmartinez

Joined Jan 17, 2007
7,552
Most, if not all, USB-C to USB-A cables (the ones ordinarily used in chargers, and to connect the phone to the computer) contain an active device that does "something" to its signal ... I don't really know the details, but as Yaakov's just said, it's quite complicated.

1636402652097.png

What I recently did for a device that I built a few weeks ago that I needed to connect to my Android phone (which has a USB C port in it) was buy a USB C to USB micro cable (which doesn't have the embedded active components), and then connected it to a USB micro to USB A adapter. That way the comms signal and the 5V connection go straight through, without any additional electronics intercepting them.... worked like a charm.
 
After a little poking around I found I may be wrong in my thinking. The USB B connectors have a pin that can be used to designate a device as a slave or master depending on how the pin is connected. I was thinking that may be where things are going wrong, and I was thinking that was carried over to the C spec, but isn't. In all reality a USB C device should work as an USB A device without signal modification as the basic connections are the same. C just has some extra pins that would have to be enabled based on if the host device is capable and sends the configuration commands, switches to the right configuration number, or whatever it takes to set up the extra pins. Good luck!!
 

sparky 1

Joined Nov 3, 2018
648
I am not sure if the project is complete but for those interested in board connector there is a picture that shows the front of the mother board
it shows the USB, on one side circled in red is the ground and also in red the other side 5V+ those points are easier to solder to a micro USB C female assembly.
https://oscarliang.com/naked-gopro-hero-9/

Some of the specs for Hero 9 battery and charger ( a hefty battery designed for a power challenge not sure what the current draw is on one of these ? )
https://gopro.com/en/us/shop/mounts...ery-charger-plus-spare-battery/ADDBD-001.html
 
Last edited:
Top