adding spi slave

[Arnaud078]

as mentionned in issue #483

[Arnaud078]

I tested that roundtripping between all the modes is fine with :
let spi3 = Spi::new_slave(spi, (sck, miso, mosi), mode, 8_000_000.Hz(), &clocks);
let spi3 = spi3.to_master_operation();
let spi3 = spi3.to_bidi_transfer_mode();
let spi3 = spi3.to_slave_operation();
let spi3 = spi3.to_normal_transfer_mode();

Slave mode is able to transmit.

I can't test that nothing was broken in bidi or master mode though.

[burrbull]

Could you add any tested example?

[Arnaud078]

added tested example of spi slave with dma in rtic

[burrbull]

Add example to Cargo.toml with rtic feature.

What about embedded-hal traits? Are they usefull for master mode only?

[burrbull]

rustfmt

[Arnaud078]

Added example to Cargo.toml. I am not sure it will solve all the build errors though, I am using undeclared crates :/

I checked embedded-hal, but I don't see any reference to slave or master mode. I don't think I can reference other traits than what was already referenced. I think we can add the 2 new type structs there (Master & Slave), as it is now duplicated in stm32f1xx and stm32f4xx.

[burrbull]

bors r+

[bors]

Build succeeded:

• ci (stm32f401, stable)
• ci (stm32f405, stable)
• ci (stm32f407, stable)
• ci (stm32f410, stable)
• ci (stm32f411, stable)
• ci (stm32f412, stable)
• ci (stm32f413, stable)
• ci (stm32f415, stable)
• ci (stm32f417, stable)
• ci (stm32f423, stable)
• ci (stm32f427, stable)
• ci (stm32f429, stable)
• ci (stm32f437, stable)
• ci (stm32f439, stable)
• ci (stm32f446, stable)
• ci (stm32f469, stable)
• ci (stm32f479, stable)
• Rustfmt

[Arnaud078]

Great ! Thank you for your time.