RE: SPI problems trying to communicate nRF9161 DK Master with ESP32 Slave

Kenneth — Thu, 06 Mar 2025 20:19:46 GMT

Hello,

An espressif,esp32 node cannot be placed under a nordic,nrf-spim node in the Zephyr Devicetree because the espressif,esp32 is not an SPI peripheral—it represents a full SoC (System-on-Chip), not an SPI device.

In Devicetree, nodes represent hardware components, and the hierarchy should reflect how devices are connected in hardware.

- nordic,nrf-spim represents an SPI controller (master), which means it can have SPI devices (slaves) as child nodes.

- espressif,esp32 represents an entire microcontroller, which cannot be a child of an SPI controller since it is not an SPI peripheral.

If you have problems communicating between an spi master and an spi slave, my suggestions are:

- make sure both devices are powered, have a common ground and same power supply level.

- connect the 4 pins: chip select, clock, miso and mosi.

- attach a logic analyzer to the pins

- execute an spi transfer from the master, look that data is correct on mosi, check values on miso is received correctly in the rx buffer on the master.

- if there are any errors, try to add a small delay (e.g. 100us) between chip select go low (active) and the spi tranfer (clock), in case the slave needs some time to be ready to receive the data.

Kenneth