fuchsiaaaaaaaaaaaaaaaaa
USB-C P/D hardware design question
I'm quite lost in the weeds of USB Type-C P/D and alt mode negotiation, so hopefully someone can help me out :)
I'm designing a simple sink, that needs to request power (not picky about voltages at all, but requesting max available would be ideal), and gets the DisplayPort signal out
From what I can see most chips don't use this configuration by default, and need either config/firmware flashing through proprietary tooling (eww), or an external controller, and there's a bunch of different (open source) firmware implementations for stm32/arduino/rp2040, with varying functionality.
What's the easiest way to get power + displayport, with the simplest (none) extra flashing steps or chips?
re: USB-C P/D hardware design question
@f0x hm, that's a tricky one, power and alt-mode are both negotiated over the CC pins, so you'd have to have your firmware negotiate the power requirements but also forward the alt-mode stuff for DP.
i'm honestly quite out of my depth with how it could be made to work. my best guess would be to use a micro with two usb-c peripherals for negotiation so you could cleanly forward negotiations.
something like STM32G081B has two type-c peripherals i think.
or you could do a static negotiation for displayport and make it work like a kinda passive adapter with power out.
but again, i have no idea how the alt-mode negotiation works.