2. Motor Driver Truth Tables

We advise against using the fourth state in the above truth table (both motor inputs low). For the Orangutan LV-168, this state results in “brake high”, which is functionally equivalent to “brake low” but less safe (it’s easier to accidentally short power to ground while braking high). For the Baby Orangutan B, this state results in coasting; there is no danger involved in using this coast state, but alternating between drive and break produces a more linear relationship between motor RPM and PWM duty cycle than does alternating between drive and coast. As such, we suggest achieving variable speed by PWMing between drive and brake when using the Baby Orangutan.

Motor 1 is controlled by pins PD5 and PD6 (i.e. OC0B and OC0A), and motor 2 is controlled by PD3 and PB3 (i.e. OC2B and OC2A). These pins are connected to the ATmega48/168’s four eight-bit hardware PWM outputs (PD5=OC0B, PD6=OC0A, PD3=OC2B, and PB3=OC2A), which allows you to achieve variable motor speeds through hardware timers rather than software. This frees the CPU to perform other tasks while motor speed is automatically maintained by the AVR timer hardware.