RalphBacon
commented
2 years ago Thank you, Brian. I found your very useful comment on YT and have replied to it. I'm pretty sure I have a way forward now. We shall see. I think this link will take you to your comment and my reply: https://www.youtube.com/watch?v=v5_0cHDSYIU&lc=UgxEpi1NsIqlmBwuilF4AaABAg
I originally posted this as a comment on the YT video, but it seems the almighty spam filter has swallowed it!
Hi Ralph, I'm wondering if this would be better done as a video reply but I have looked into PD a bit in the past so I can probably help. I am no expert on the subject though!
In order to negotiate PD, you only really need 4 connections: VCC, Ground, CC1 and CC2. You can get USB-C Connectors that only have 6 nice and chunky pins (at least relatively speaking) that should be even hand solderable. (I've used LCSC part C283540 in the past and it has worked well). the 6 pins are 2xVCC, 2xGND, CC1 and CC2
If I was making this project, I would put two of the above USB-C connectors on your PCB and pass them through one to the other (making the VCC and GND traces between them as big as possible), plug one into your charger and the other into your phone and as you mention connect some form of Buck converter to get your 5v or whatever for your Arduino. The phone and the charger should still do whatever dance they already did and you can just leech the power from the VCC and Ground lines
Don't worry about the cable you use. Basically all cables are capable of doing PD negotiating (as mentioned above there is only 4 wires needed) but some circuitry is required for the cables to advertise that they can do more than 3A, that shouldn't be a problem for your phone.
One thing that I have found very useful for PD things is an inline USB-C voltmeter so you can see what a device and a charger have negotiated. They can be bought pretty cheaply from Aliexpress but there is one Amazon uk that would arrive much faster (B0927KW6W4)
If you want more info I'd be happy to try help!