Best protocol/way to simply connect 2-3 Arduinos to main Arduino

Projects Networking, Protocols, and Devices
8

@MikkelD Welcome to the forum.

SPI is actually simple; it just needs a few wires more than I2C and UART for a single connection. For that you get

  • one data wire for each direction (Master -> Slave, Slave -> Master)
  • a clock signal that tells the slave when the data is valid and when the data line gets updated
  • one chip select signal for each slave

This makes SPI faster and more robust than I2C and UART.

In your case you would need 7 lines and could use just one SPI peripheral.

If you have 4 hardware UARTs on your Mega that can work as well.