I built a Arduino robot car which accepts instructions via bluetooth. The instructions are pretty simple, they tell the car to stop, go forward, reverse, turn left or turn right.
When I have the car powered through the computer USB (ie when I have just uploaded the sketch), all works fine. However, when I run off independent battery power, the arduino seems to restart whenever I give the car an instruction which means the motors have to operate.
I know the sketch is restarting inside the Arduino because the blue tooth terminal displays the startup text which is inside the 'setup' function.
What is going wrong here? What issue am I encountering?
The board is an Arduino UNO with an Arduino Motor Shield attached. The blue tooth and two sonic sensors are attached to the motor shield pins.
Also, I have a 9V battery attached to the motor shield. Plus 4 times 1.5V batteries powering the UNO. Am I screwing up the power at all? Getting too much? Or too little?