Shared SPI bus between devices with different SPI modes

[dan-corneanu]

I have a small board that has 2 devices attached to the same SPI bus

• AD9833 DDS that uses SPI MODE 2
• MCP41010 Digital Potentiometer that can use SPI MODE 0 or MODE 3

Each device has its own CS pin.

I am using the following two drivers

• https://github.com/eldruin/ad983x-rs.git
• https://github.com/dan-corneanu/mcp4x-rs.git

The problem that I am facing is that my program can only communicate with one of the devices because
the SpiDevice can not change the mode of the SpiBus.

I think this design decision was discussed back in 2022 in this comment #351 (comment).

Could you please advise on how I could address this problem in my code?

If interested in the code of my application you can have a look at this branch https://github.com/dan-corneanu/ad983x_signal_generator/tree/features/configure_ushell.

[eldruin]

At the moment this must be implemented in a HAL-specific way. The difficulty will depend on the HAL you are using (I cannot access your application repo) but it will probably involve rewriting a bit of embedded-hal-bus so that when a device is activated, the bus is reconfigured.

[dan-corneanu]

Have made it public.