USB-C instead of micro USB

orangecrab-fpga / orangecrab-hardware

ECP5 breakout board in a feather physical format

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USB-C instead of micro USB #18

Closed jmi2k closed 3 years ago

jmi2k commented 4 years ago

Pros:

It's the new standard, and as time passes, Type C cables will be more common than micro USB
It has better mechanical properties than micro USB
Reversible!

Cons:

It can confuse users, as the board is wired to make use of at most USB 1.1 (even High Speed is not possible according to the docs). Although not related, people usually assume Type-C => USB 3.0.
microUSB cables are cheaper (though that might change).

Feather format allows for Type-C connectors to be used instead of micro USB, so it would remain Feather-compatible.

rowanG077 commented 4 years ago

USB 3.0 is possible using the ECP5-5G variant.

gregdavill commented 4 years ago

It's a good idea. Swapping in a USB2.0 only USBC connector would be a quite easy change, and not effect any other hardware one the board.

While USB3.0 is technically possible with the SERDES that the ECP5/ECP5-5G has (3.2Gbits/5Gbits) I've not seen this working yet. So I'm hesitant to rush to put that in a r0.3 hardware version. That said @enjoy-digital is making good progress on that front here: https://github.com/enjoy-digital/usb3_pipe

Routing SERDES into the USB3 lines does not automatically guarantee we can operate in alternate modes (DisplayPort/HDMI) that's another can of worms using the USB billboard system, and might mean we need to include a dedicated USBC PD controller.

jmi2k commented 4 years ago

I was more concerned about the connector itself more than the protocol. It's awesome to see that you like the idea of putting an Type-C connector while keeping the underlying USB 2.0 system, and I would love to receive my board with it.

About the protocol, I prefer a simple and clean board design (as there are alternative boards which already offer more capabilities, including USB 3.0). In fact, I was astonished when I saw the schematics because there is little hidden: it's a FPGA attached to some DRAM and little else. It's a really understandable system. However I can understand the appeal of a full-featured USB-C connector...

gregdavill commented 4 years ago

I am open to changing it. Unfortunately, at-least at the time of writing this, we already have the design locked in for the group-buy. So it's not possible to alter those designs as they're already in the pipeline.

So this change would likely come on a r0.3 board release.

jmi2k commented 4 years ago

It's fine, I hope there is a group-buy for r0.3 too

gregdavill commented 3 years ago

Implemented in r0.2.1: https://github.com/gregdavill/OrangeCrab/issues/25