SPI slave not receiving messages

[Herre Vermeer]

Hello DevZone,

I am using the following example: github.com/.../ncs-spi-master-slave-example.git to test the functionality of the SPI slave device driver under zephyr. However, data does not seem to arrive at the SPI Slave RX, sent by the SPI TX. I have connected the pins as follows:

A5 <--> D0
A4 <--> D1
A3 <--> D2
A2 <--> D3

And I have compiled this repository for the nRD52840dk. When observing the NRF terninal, I get the following output, which makes it appear that the input for SPI_slave_RX is floating:

I have analyzed the logic state on the MOSI pin and I get the following, which makes it seem valid that data is on the pin:

I have also tried enabling pull up resistors by adding: bias-pull-up; to the &pinctrl, but this does not seem to fix it.

When compiling, I get a warning: Experimental symbol SPI_SLAVE is enabled.

Is there any knowledge on whether the SPI Slave drivers are working at all, if so, what can be done so that communication is possible from master TX to slave RX?

[Jørgen Holmefjord]

Hi,

I'm seeing similar behavior on my end when testing this on a nRF52840 DK, but my Slave RX buffer contains all 0xff. I checked with the developer of the sample, and he say he has seen similar behavior on some devices as well. There might be a misconfiguration somewhere. I will try to debug it a bit more to find the cause of this behavior.

Best regards,
Jørgen

[Herre Vermeer]

Hi Jorgen,

What exactly is the difference between the NRF and NRFX drivers?

[Jørgen Holmefjord]

Hi,

If you by NRF mean the nrf_%peripheral%.h files inside NRFX, this is the peripheral HAL, which is not a driver but only an abstraction layer of the hardware interface to the registers. The nrfx implementations (nrfx_%peripheral%.c/.h) is the driver implementations.

In nRF Connect SDK there is also additional driver implementations that adapts to the Zephyr RTOS APIs. These drivers are typically implemented using nrfx_ driver APIs.

Best regards,
Jørgen