SPI Slave not working on nRF9160DK

RE: SPI Slave not working on nRF9160DK

mike.bush.valtech — Wed, 25 Sep 2024 12:54:22 GMT

Turn out the CS line from the master was active high instead of active low. For anyone needing SPI working on the nrf9160dk working sample can be found here: https://github.com/mbush91/nrf9160dk_spi_test

RE: SPI Slave not working on nRF9160DK

Menon — Fri, 20 Sep 2024 13:18:46 GMT

Hello,

Is there any error message or error code? If not, try adding debug logs or using error handling to determine whether the SPI driver on the nRF91 is receiving and processing data correctly. Capture any errors returned by the spi_read calls on the nRF91 side.

One more thing I noticed while checking the application is that you have defined small buffers on both sides (rx_buffer[2], tx_buffer[2]). Ensure that the data you're sending fits into these buffers. If you're transferring more than 2 bytes, the buffer size should be adjusted accordingly.

Kind Regards,

Abhijith

RE: SPI Slave not working on nRF9160DK

mike.bush.valtech — Thu, 19 Sep 2024 11:55:38 GMT

Hi Abhijith,

I'm currently building with the v2.6.1 SDK. uart1 is disabled in both the nrf52 and nrf91 applications but I've also tried switching to spi3 which doesn't work either. I can see data on all four lines with the logic analyzer but the data doesn't seem to make it into the driver

RE: SPI Slave not working on nRF9160DK

Menon — Thu, 19 Sep 2024 07:07:59 GMT

Hello,

Which SDK version are you using? I reviewed the 91 overlay, and it looks good to me. However, please check if the selected pins (P0.17, P0.18, P0.19, and P0.21) are not being used by other peripherals or functions in the application. If any of these pins were previously used for UART1, ensure that disabling the UART has fully released them for SPI use.

Could the issue be that the nRF52 is not correctly driving the SPI clock (SCK) as the master and is not initiating SPI transactions? The SPI slave (nRF91) relies on the master to start transactions, so if there’s no active clock signal from the master, that could explain why the RX buffer on the nRF91 isn't receiving data. Can you verify this with a logic analyzer or oscilloscope?

Kind regards,
Abhijith