Arduino as SPI Master & I2C Slave at the same time?

Hi all,

I was wondering if anyone knew if the following is feasible: I'd like to have an arduino (ATMEGA32U4) act as an SPI Master whilst also acting as an I2C slave.

It's controlling 8 ATMEGA328's over SPI as an SPI master, and also acting as an ISP. It's primarily controlled over USB, but I'd like to have the option of also controlling it over SPI. To that end, I'm looking to get an SPI-I2C bridge, so that I can talk to it over SPI.

In this set up of course, it's an SPI Master but an I2C slave to the bridge. Is there anything problematic with this setup? Are the interfaces on the ATMEGA32U4 for SPI/I2C separate? It is just a matter of manipulating the proper registers to set it as an I2C slave and setting up the interrupts?


I2C and SPI are independent, you can have an SPI master act as an I2C slave.