Do the Serial stuff again

[Lokathor]

The serial port stuff didn't survive the update to 0.4, it's still in the backup directory.

[ids1024]

"SIO Normal Mode" is a variation on SPI that doesn't use chip select), so embedded_hal::spi::SpiBus may also be useful. As well as just the digital pin abstractions for the "GPIO" mode of the link port.

I still need to setup hardware properly and write some code to test these things.

[Lokathor]

I was setting up the TOC for a revised https://github.com/Lokathor/gba-from-scratch lesson set and i had to remind myself to even put the serial port down as a subject.

I really don't know anything about it XD

[ids1024]

I mainly know what gbatek says about it.

For the UART mode, the link port can act as a UART, with somewhat more limited options for baudrate and such than serial ports often offer. "Normal Mode" is a variation on SPI (some SPI peripherals don't need chip select; not sure if they'd work or need a different connection. Or if the fourth pin could be manually set in RCNT). Not sure how to compare "Multi-Player Mode" or "JOY BUS Mode" to anything. The four data pins can also just be used as digital inputs or outputs.

I don't even have two GBAs to connect, and I guess emulators only have limited link port support. I'm just wondering what the wildest thing I could connect to a GBA is. (Serial modem? Maybe not worth buying one just to connect to a GBA...)

(Probably more useful to see how the embassy async executor could be used on the GBA, and things like interrupts could be handled with async.)