DRV8835 module - Motors on briefly at power up

Support Motor controllers/drivers and motors
1

I have a problem with my Pololu DRV8835 module whereby the motors turn on briefly when power is applied to the chip. Can’t really have a robot shooting off every time it is switched on.

Anybody else experiencing this? What is the remedy?

[Clarification]
Looking more closely, the problem is initial noise on the PWM input as the microcontroller powers up. The 8835 seems to be happy with noisy DC as the PWM signal. I’m not sure what I can do about it yet. I haven’t had the problem with full H-Bridge drivers, perhaps since both control inputs can be off, leaving no voltage at the motor. Seems more like good luck.

Regards
Murray

2

Hello, Murray.

Depending on what state the mode is in and what your control signals are doing as your microcontroller starts up, that could be expected behavior from the driver. If you tell me more about your system, I might be able to make suggestions on how to get your preferred startup conditions. What microcontroller are you using? Which of our DRV8835 boards are you using? How are you using the mode pin?

-Jon