Is it possible to connect 2 Raspberry Pi 3's together using cable? (I read somewhere and show some videos that an Arduino can be connected to a Pi using a serial cable.)
One of the Raspberry Pi's will be used as a gateway and a CoAP server that communicates with sensor nodes that is on the other Pi. The sensor will be a DHT22 sensor for temperature.
The Arduino part of the question is because I saw this. Just asking if it can happen pi to pi.