Currently there's an 8 pin connector that has two CAN buses plus power and ground. But I'm probably gonna have to drop one if I want the USB port to have dual-role functionality since it shares pins with the I²C bus I'd need for the USB controller chip.
Alternatively I could maybe use a microcontroller as a protocol converter but then the backpack expansion header would have to go away. That'd free up some space but I'm not sure it'd all still fit since it's not an integrated solution.
But another big choice is I've realized I could probably power the system via the USB port, too, using the 20V/5A standard. PCIe connectors are (kinda) rated to 75W which would be enough. For that I'd have to use *both* the CAN/I²C *and* the expansion header GPIO lines.
So, like, I dunno.
1x CAN bus
1x DRP USB-C with Power Delivery + Accessory support
1x CAN bus
1x DRP USB-C only
1x GPIO/SPI Expansion Header w/Clock source
2x CAN bus
1x UFP USB-C
1x GPIO/SPI etc
Did a bunch of other posts on Twitter I forgot to crosspost, but that's okay because: NEW PLAN! (Re)discovered the UPD350B aaaaaand yep, it uses SPI, does PD 3.0 comms, has GPIO, it's pretty much fantastic as far as USB-C port controllers go. (Which, you know, could be better, could be worse.)
Basically I'll have parallel SPI connections for the GPIO header + controller, maybe put some of the GPIO of the port controller onto the header, too. Will see, have to fuck around. PD 75W+ may be done through the header too. All stuff to figure out as I work on it.
When you're trying to label pins in a compact manner but are basically reduced to doing pixel art.
*looks at the analog inputs symbol, only sees a dreidel*
On the plus side, I'm hoping to get this sent off to the fab by the end of the month. We'll see if it happens or not, but I've gotten past most of the roadblocks in making this so, fingers crossed!
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