Connecting a Zero(SAMD21) and 328P AND RFM95

Official Hardware Classic Zero
1

Hi,

I need to connect a Zero to a 328P which act as a co-processor connected to a RFM95. This is because of the low power mode of the 328P. The 328P handles all the radio stuff and needs to receive and send commands to a Zero. I'm considering SPI as a connection between Zero and 328P as it's fast and reliable. My question is now: SPI is used by the RFM95, can I also connect a 328p via SPI? Or is only one device possible with SPI in this case?

2

RFM95 and Zero both run on 3.3 volts. You would need to level shift SPI pins if the 328P runs at 5.0 volts.

Zero provides power management features. I don't see why you wouldn't want to use Zero's SPI function to directly connect to the RFM95.

3

Thanks for your reply. The 328P also runs off 3.3V and is very energy efficient. Much better than the Zero's SAMD21 chip plus there is an excellent RFM95 lib that uses the low power RX feature of the RFM95.
That's why I'm asking for help how to connect those two µCs AND a RFM95