How to communicate between two arduino boards?

Projects Programming
1

I am using an arduino mega and an uno for a project and the uno is controlling the robotic arms. i want to send a signal from my mega to the uno and start moving the arm. Now I don't know if this is even possible but if it is, please tell me how to.

2

Now I don't know if this is even possible

It is.

please tell me how to.

How do you want to "send the signal"? I2C? Serial? Set a input pin HIGH?

3

I want it through serial communication. Thank you so much for guiding me. Please elaborate on this!

4

Please elaborate on this!

What do you need to know? On the Mega, pick a matching pair of TXn and RXn pins. Connect them, and ground to the UNO. Use Serialn.print() to print the data of interest (or Serialn.write() to send binary data).

On the UNO, choose two unused pins, connect the wires from the Mega to them, and create an instance of SoftwareSerial using those two pins. Use the available() and read() methods of the SoftwareSerial class to get the data from the Mega.