I'm fairly new to the practical side of robot building, and have almost completed construction on my first autonomous bot. I studied Cybernetics at university, so I'm alright at the software stuff, but the electronics can stump me sometimes.
I'm using a PIC16F876 to control a differential drive 'bot using 2 DC motors. The test circuit I've made uses an H-Bridge to control the direction of the motor. The circuit is set up on a prototyping board. I know the control signal from the control circuit is OK. The output of the H-Bridge is providing a voltage drop of +3.3V across the connector for the motor. however, when I actually connect the motor, it nothing happens (the motor doesn't turn). If I measure the voltage across the connection terminal again, I get ~+0.5V. If I simply connect the battery cells directly to the motor, it turns fine, as I'd expect. The motor is rated to operate at 3V.
What am I doing wrong, and why isn't my motor turning when it's connected to the circuit?
It's doing my nut now, and I'd appreciate some help!