Does nRF52840 SPIS configure GPIO pullup for CSN?

[machine]

Previous versions of nrfx_spis.h:nrfx_spis_config_t had a "csn_pullup" field but the latest version does not.

The nRF52840 Product Specification is not very clear about how the CSN pin configuration is handled.  Does the GPIO pin need to be configured using the GPIO PIN_CNF registers or does the SPIS take control over the PSEL.CSN pin?  Will SPIS override GPIO configurations for this pin?

Thank you!

[Jørgen Holmefjord]

Hi,

The pull config is set on the GPIO before the pin is set in the SPIS peripheral. The SPIS peripheral will control the pin once it is set in the peripheral, but this pull and drive-configs from the GPIO will still be effective.

Previous versions of nrfx_spis.h:nrfx_spis_config_t had a "csn_pullup" field but the latest version does not.

I'm not sure what you mean by this. I checked multiple versions of nrfx (1.6.2, 1.8.0, 2.0.0, 2.1.0) and they all have this member in the config struct.

Best regards,
Jørgen

[machine]

I was looking a Zephyr 2.2.0 "modules/hal/nordic" which seems to pull from master here:
 https://github.com/NordicSemiconductor/nrfx/blob/master/drivers/include/nrfx_spi.h

[Jørgen Holmefjord]

There is still a csn_pullup member in the config struct in the master branch. Your link was for the SPI master driver, not the slave driver.