Change Polarity of Chip Select line for SPI devices

[benkokes]

Hi,

I would like to know the correct way to change the polarity of the CS line for SPI devices. The SHARP memory display is opposite of most SPI slave devices so I need to use the CSNPOL register so the SPI subsystem can correctly handle the line.  I have the Sharp display and an RTC on the same bus, each one requiring different polarity for its operation.

Currently I am using SDK 15.2 with the SPI manager, and am following the SPI manager example from the SDK. I would prefer it to be a part of the SPI configuration structure so I can use multiple configurations.

Any insight would be appreciated.

Thank you and happy new year!

-Ben

[Jørgen Holmefjord]

You should not have to enable NRFX_SPIM2 to use NRFX_SPIM3, but you might have to remove the legacy config entirely from the sdk_config.h file to avoid that the NRFX config will be overwritten in the legacy layer apply_old_config.h. Please reference the sdk_config.h file in nrfx_spim example in SDK 15.2.0, where only NRFX_SPIM3_ENABLED is set.

[benkokes]

Ah yes, I see. Thank you. 

Is it possible to have 2 seperate NRFX SPI configurations exist simultaneously for the same instance?    I have 2 slave devices attached to the same SPI bus. I would like to define a specific configuration for each device ( CS Pin and CS behavior). I would prefer the CS line for each to be handled by the SPI subsystem. Is this possible?

[Jørgen Holmefjord]

Unfortunately, this is not possible with the SPI driver, and it is exactly why we have implemented the SPI transaction manager. If you are using the driver, you need to handle this manually in your application.