NRF9160 zephyr SPI - CS stay low too long

RE: NRF9160 zephyr SPI - CS stay low too long

Mateusz Gancarczyk — Thu, 24 Feb 2022 13:56:00 GMT

I figure out this problem - looks epic :) :

I can't share a code because it's commercial but:
it use 2 gppi channels. One connect SPIM Start event to gpiote toggle pin task and second connect SPIM end event and the same gpiote toggle pin task.

RE: NRF9160 zephyr SPI - CS stay low too long

Saleh — Mon, 03 Jan 2022 17:50:39 GMT

It seems the problem is coming from Zephyr side, a similar question was asked before and results show that this annoying delay is the normal behavior of the current Zephyr's version.

https://devzone.nordicsemi.com/f/nordic-q-a/81966/slow-spi-performance-with-zephyr

RE: NRF9160 zephyr SPI - CS stay low too long

Sigurd — Mon, 20 Dec 2021 08:59:08 GMT

Hi,

I see similar results here.

Zephyr SPI API:

nrfx driver(based on this example https://devzone.nordicsemi.com/f/nordic-q-a/70105/how-to-use-spi-interface-in-a-zephyr-sample-example/288587#288587 )

When the CS pin is set high/low is handled in the SPI driver(SW). There could be ways to optimize the driver SW here, but if you need minimal/no latency here, and the SPI sensor support that, I would look into using (D)PPI to toggle the GPIO. https://devzone.nordicsemi.com/f/nordic-q-a/63466/control-of-ss-pin-of-spi-with-ppi