This code was written in the summer of 2015 for a rolling robot guided by a Sonar and using two wheels on the left and right. It is also configured to accept interrupts from pin3 (int1). Hardware Used: Arduino Uno, Sonar, Servo, 2 3V-6V DC Motors+Wheels, Adafruit Motor Shield (made by Sainsmart) My code for the interrupt cycle is in my "SonarInterrupt.ino" file.
