I'm working on a project where I want to set up a network of Arduinos. I want to have one master Arduino that talks (two-way communication) to several slave Arduinos within the network. I plan to do this via an SPI connection and found many examples.
However, each of the slave Arduinos needs also to talk to a MCP4922 DAC via SPI. That means that each slave Arduino needs to be master for a second SPI connection. Is there a way to implement this? So far I'm working with Arduino Nano but I could switch to a different model. A different DAC would also be possible if necessary.
My last idea is to use I2C to get the data from the slave Arduinos to the master and do the backwards channel via single digital connection. However, I need to count I/O ports for that.