How to Make Communication between Two Arduino Boards?

In this tutorial, we will use SPI Protocol for communication between two Arduinos. Here one Arduino will act as Master and another one will act as Slave, two LEDs and push buttons will be connected to both the Arduino. To demonstrate SPI communication, we will control the master side LED by the push button at the slave side and vice versa using the SPI Serial communication protocol.

To start communication between master and slave we need to set the required device's Slave Select (SS) pin to LOW, so that it can communicate with the master. When it's high, it ignores the master. This allows you to have multiple SPI devices sharing the same MISO, MOSI, and CLK lines of master. As you can see in the above image there are four slaves in which the SCLK, MISO, MOSI are common connected to master and the SS of each slave is connected separately to individual SS pins (SS1, SS2, SS3) of master. By setting the required SS pin LOW a master can communicate with that slave.

Before start programming for SPI communication between two Arduinos. We need to learn about the Arduino SPI library used in Arduino IDE.

Check out the complete step-by-step guide for communication between Two Arduino which consists circuit diagram, code, required libraries, and other additional information.