I'm using an L298N driver (powered by a 12V, 1.5A adapter) on a MEGA Sensor Shield (powered by a USB cable). Everything works fine and I can control the direction and the speed of the DC motor, however when I activate anything else on the shield - the motor will not spin unless I set the PWM to its highest frequency.
Please note that I am using Max/MSP to controls the motors, so when I say activate - I mean setting up the PinMode of pin 17 to "Servo". If I set up the Servo first and then the DC motor pins - it will again start spinning only at maximum PWM, there's no signal reaching the driver otherwise.
Am I missing something in my setup? I would use Arduino Mega on its own, however I need to use over 25 Servo motors together with the L298N driver, which makes the sensor shield inevitable.