Adding several SPI slaves to one RPi SPI bus and adding several SPI buses to one RPi

[hcet14]

Thank you for your quick answer.

@Sineos

On the same SPI bus you need to differentiate the devices via an own CS pin. MISO, MOSI, SCLK are shared. The active SPI device is chosen by pulling the CS pin high. This is done automatically by Klipper.

I guess every SPI bus works like this.

@Sineos

Above is the case, e.g. when you share a MAX board on the same SPI bus as your stepper drivers.

Yes, e.g.

@Sineos

On the RPi it is a bit different.

I guess you refer to ADXL345 Raspberry pi4 multi SPI - #12 by koconnor
But, Raspberry Pi 4 - Multiple SPIs and Raspberry Pi 4 - Device Tree should get writ of that. Do I understand something wrong? Of course we have to consider bandwith and how the whole SPI bus is connected (cables, connectors, etc)!

@Sineos

Example:

Thanks a lot.

@Sineos

• SPI0 and SPI1 pins are on completely different ALT functions from the SPI buses 3 through 6
• SPI0 and SPI1 partially overlap with SPI4 and SPI6

Yes, I read about that.

@Sineos

• SPI1 and Klipper seems problematic. Best to avoid it

Could you please explain why or add a link to read about?

@Sineos

• If you want to use the buses SPI3 to SPI6 then deactivate the default SPI overlay

That should be handled here Raspberry Pi 4 - Device Tree, or?