Application Notes

M1_reverse(63);

Motor outputs M1A (blue) and M1B (yellow) for driving “reverse” at 25% duty cycle

(OCR0B=63, OCR0A=0). The green channel shows motor current.

If you use the Pololu AVR library, the equivalent function call would be set_m1_speed(-63). (see the Pololu AVR

command reference [http://www.pololu.com/docs/0J18/7] for more information).

Here the M1A output is high for 25% of the time and low for 75% of the time, and the M1B output is low 100% of

the time. While M1A is high, the motor is being driven in reverse, and while M1A is low, the motor is braking. The

net effect is that the motor speed is approximately 25% of its full speed at the supplied motor voltage.

The green line shows the current flowing through the motor. Note that the zero point of this has been moved up since

the current is flowing in the opposite direction when the motor is moving in reverse. At lower speeds, the motor noise

decreases and the current draw does not change much from one PWM cycle to the next.

Application Note: Using the Motor Driver on the 3pi Robot and Orangutan Robot

Controllers

Corporation

6. Motor Voltage Waveforms Page 9 of 12