Dual BDC Controller

Apr 4, 2017

1 min read

This board was designed for small battlebots with dual brushed motor drive. Delivering a peak current of 3.6 Amps with up to a 20 volt input voltage. For control, the board has two pwm inputs and jumpers to enable and disable on board arcade mixing.

This was a quick project to that was done over the course of a weekend. Due to the small size and minimal number of components this was an easy task. This was the first board I'd made using a (new to me) cad program, (KiCad). The board is based off the DRV8872 DC motor driver, with an atmega 328p for control.

Additional features include, active stall and over current protection. The DRV8872 will prevent current draw that exceeds 3.6 amps and go into an error state, and after a certain time, resume normal operation. This behavior is good, but a better approach to protecting the drive motor can be implemented. During a fight it is common to lose one side of you chassis and in the heat of the moment slam on the sticks to try and make your bot move. The problem with this is that one side of your chassis, if you're arcade mixing, will constantly be getting stalled and slammed with full current. My method to prevent damage to motors is to detect these stall conditions and allow for cool down time, potentially ignoring all PWM input once a motor has stalled for an extended period of time. This will allow the driver to not have to worry about damaging their drive motors while trying to move around a battlebot with a damage drivetrain.