This is an interesting DC motor controller that uses a MOSFET H-Bridge with AVR ATmega8 micro controller. This looks like a nice start to powering your next robot project.
Here is a very simple project of controlling a small DC-motor (taken from an old personal cassette player) with ATmega8. The ATmega8 is having three PWM channels, out of which two are used here. PWM waveforms are fed to MOSFET (RFD3055) H-bridge.
More about Simple PWM DC motor control with an AVR
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