So I'm using arduino + 2 channel relay shied v1.4, how do I pin my arduino to raspberry over gpio And what the differences between UART and GPIO

Serial communication between arduino and raspberry

Topic		Replies	Views
Communicate arduino to raspberry pi gpio Networking, Protocols, and Devices	2	1324	May 6, 2021
2 pin serial communication Programming	4	1935	May 5, 2021
Connessione tra Arduino e Raspberry distante quasi 10mt. Hardware	18	9019	May 7, 2021
Comunicación serie entre RaspberryPi y Arduino Español	1	1509	May 6, 2021
can I use the RX TX pins (0/1) to interface with my pi? Programming	4	721	May 5, 2021