MKR WAN1300/1310: microcontroller to LoRa-module communication?


I'm trying to understand how ATSAMD21G18A communicates with Murata LoRa-module.

I assume with SPI bus on PA12_MOSI_TX, PA15_MISO_RX and PA13_SCK.
With scope I can see traffic on PA12_MOSI_TX and on PA15_MISO_RX but NO clock signal on PA13_SCK. And I can not see PA14_RF_SSN pulled down during the communication.

How that could be possible that no clock signal? How do they communicate?

I have checked with MKR WAN 1300 board and with MKR WAN 1310 board and same thing. I'm testing with Arduino MKR example sketch FirstConfiguration.ino.


Perhaps the MKRWAN is using the Murata module in UART mode, i.e. with RX and TX communications.

Not sure you can communicate direct with the SX1276 module on the Murata module, comms appears to be through the Muratas STM32 processor.

Hmm... could somebody confirm if it's in UART mode.
Yes, you are right communication goes to STM32 processor in Murata module.