2. Motor Driver Truth Tables

 input   Orangutan LV-168 output   TB6612FNG-based controllers 
 PD5, PD3   PD6, PB3   M1A, M2A   M1B, M2B   motor effect   M1A, M2A   M1B, M2B   motor effect 
H

H
L
L
brake low
L

L
brake low
L

H
L
H
“forward”*
L

H
“forward”*
H

L
H
L
“reverse”*
H

L
“reverse”*
L

L
H
H
brake high
OFF (high-impedance)

coast

* Note that the concept of “forward” is arbitrary as simply flipping the motor leads results in rotation in the opposite direction.


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 TB6612FNG-based controllers (i.e. the Orangutan SV-xx8, Baby Orangutan B, and 3pi robot), this state results in coasting; there is no danger involved in using this coast state, but alternating between drive and brake produces a more linear relationship between motor RPM and PWM duty cycle than does alternating between drive and coast.

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 ATmega48/168/328’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.