Rasbery Pi 3 & Espruino Serial Communication

The Raspberry Pi GPIO is 3.3v I think, so it should work fine. The problem with attaching multiple devices is that the Pi's GPIO isn't very powerful, so would probably struggle over longer distances.

Also, Serial isn't set up very well for multiple devices connecting. You'd need to either:

• Daisy-chain the Espruinos end to end (each one forwards the data it receives on to the next)
  
• Set up all the Espruinos to use af_opendrain mode for the serial TX line, and then add a pullup resistor (which would allow them all to share the same TX line). Sharing the RX line isn't a problem.
  
  

Hope that helps!