I want to use the Arduino MotorShield to drive 2 motors: 12V, 78mA max each.
The documentation of the MotorShield says: "If your motor require more than 9V we recommend that you separate the power lines of the shield and the Arduino board on which the shield is mounted."
Is this necessary and what is it good for?
12V is the max you can put into the regulator without a heatsink. If you get the regulator hot enough, it will go into thermal shutdown.
To me it seems the easiest to power the MotorShield with 12V and let the Due recieve its power through the MotorShield.
However, if I follow the recommendation, separate the power lines and power MotorShield and Due separately: can I use the same external power supply for both (i. e. 12V) or should I power the Due with only 9V to relieve the voltage regulator of the Due?
Many thanks for any hints!
You should power the DUE separately so you don't risk melting anything.