[riot-notifications] [RIOT-OS/RIOT] cpu/sam0_common/spi: move out pin muxing into spi_acquire / spi_release (#14107)

Juergen Fitschen notifications at github.com
Fri May 22 11:56:34 CEST 2020


Two other findings, while I had a look into the Wikipedia article of SPI [1]: The figure showing the different SPI modes shows two interesting points:

1. If CPOL is 1, the SCK line is high when the bus is idle. Thus, we may should set the GPIO accordingly?
2. The MOSI line may be High Z during idle. If implemented this by just muxing and demuxing the SCK line and for the `samr30` thats also working! But I don't know if every SPI slave is happy with MOSI being High-Z ... I would leave it this way it's implemented currently.

What do you think?

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[1] https://en.wikipedia.org/wiki/Serial_Peripheral_Interface#Clock_polarity_and_phase

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