USB peripheral support

[liamkinne]

Adds the required implementation to support USB device with usb-device and stm32-usbd.

[liamkinne]

@usbalbin I have mostly ripped this implementation from the F3 repo. However I'm not sure if it is not working correctly or if I have a hardware issue since the G4 board I'm using doesn't feature a USB connector.

If you have the ability to test using the example that would be great. Otherwise wait until I can get my hands on the correct hardware before merging.

[usbalbin]

What is the different between critical_section::with (requiring a new dependency) and cortex_m::interrupt::free as used in src/serial/usart.rs?

[usbalbin]

If there would be no downside, I would prefer to avoid the extra dependency

[usbalbin]

Note there is also #50 . @kevswims what is the status and/or plans of #50?

[usbalbin]

@usbalbin I have mostly ripped this implementation from the F3 repo. However I'm not sure if it is not working correctly or if I have a hardware issue since the G4 board I'm using doesn't feature a USB connector.

If you have the ability to test using the example that would be great. Otherwise wait until I can get my hands on the correct hardware before merging.

I do not have access to such hardware right now. Might in several months, maybe, but not now.

BTW, thanks!

[liamkinne]

@usbalbin didn't see #50 but I will have a look at it an see if there's anything to bring across.

I'll go ahead and order the expansion board to give my dev board USB. If that doesn't fix it, my best guess is there's a clocking issue causing the host to reject the connection.

[usbalbin]

@usbalbin didn't see #50 but I will have a look at it an see if there's anything to bring across.

I'll go ahead and order the expansion board to give my dev board USB. If that doesn't fix it, my best guess is there's a clocking issue causing the host to reject the connection.

Awesome!

Correct me if I am wrong, have not looked into USB, but I believe I read about some sort of clock recovery system in #50 for running without a crystal in case that helps.

[kevswims]

Note there is also #50 . @kevswims what is the status and/or plans of #50?

I have switched my project over to use embassy which is why I haven't done anything more with that PR. As far as I remember with a bit of cleanup it should be good to go in if someone wants to use the work from it. I'm happy to answer questions or assist with that if someone wants to take it over.

[liamkinne]

@usbalbin with the correct hardware, all is working now.