Is it possible to control 3 Arduino Motor Shields R3 with Arduino Mega 2560?

Hello Community,
for a Project I need to control 5 DC motors and one servo motor. All of them need 12 Volts.
I bought one Arduino Mega 2560 and 3 Arduino Motor Shields because I thought that I can control the motors via them if I just don´t plug the shields on the board but connecting them separated via wires to different pins of the mega.
So I wrote my programm and finished the wiring. First time of testing 12V and 5V circuit was completely separate (no common ground) --> All motors turned on instantly at full speed and my Mega´s USB Chip got grilled when I turned the 12V power supply off. So I thought the reason for the failure was that I had no common ground. Bought a new Mega and did it again with common ground. ---> Mega got grilled instantly when I turned the power supply on and my Laptop crashed (I had to remove the battery of my Laptop to start it again) .... :o Now I don´t know what I should do next because I don´t want to grill my next mega, too ....

Please post schematic or picture of how you have this wired, it sounds as if some how you are supply the mega with 12Volts or you are drawing to my current through the 5V side.

If the 12V was isolated from the 5v connecting the grounds would not be the issue.

I will do this tomorrow morning for you. Do you maybe know a good programm with which I can do it well? :slight_smile:

Hi again,
I finished the circuit Diagramm this morning. I hope you can work with it :slight_smile:


Has anyone already found an issue or has an idea what can cause my problem? The only Thing i can consider is that i had a wiring error from Megas 5V-Pin to the MotorShields Vin-Pin instead of the 5V-pin. Thats the only thing i can consider that causes the shield to draw too much current through the controller. I checked the connections about three to four times and I thought that everything is right but I can´t assume any other issue.

Daniel :slight_smile:

I think that I have found the issue.
Yesterday I checked Megas´ and Motorshields´ schematics and saw that there is a NC solder bridge that connects Vin-Pin directly with the VMOT-Clip to which the +12V power supply is connected.
So if I should have done a wiring mistake from 5V-Pin of the Mega to the Vin Pin of the MotorShields the 5V and the 12V power supplys are parralel connected, this would have caused a potenzial equalization which destroyed my controller.

I opened the solder bridge for safety now and when my next Mega arrives I will test my work again and hope it works now :smiley: