DSMC Problem

Here is a problem I am experiencing with the micro motor controller.

The two motors I have tried are GM2 and Tamiya 70110. With the GM2 attached to the motor controller and applying 5V to Vin, motor would only run at speed setting of 25 or below on controller. At speed setting of 50, motor would run for about 1ms and stop. Same thing happens for higher speed settings.

With no load on motor controller, I tried to observe the PWM waveform at the output of the controller. The shape looks correct and frequency is around 650 Hz. Even the duty cycle changes with different speed settings. I assume the controller is functional.

By the way, there is already a capacitor across the motor. Anyone know the motor controller output is not modulating with load applied and speed setting higher than certain value? Thanks.


It sounds as if you are trying to power the motors through a voltage regulator (how else are you getting 5V?). Using a voltage regulator to power a motor is usually not a good idea for several reasons. The main problem is that most regulators cannot handle the high current and the big fluctuations that come from controlling a motor using PWM. It is likely that as you increase your speed setting, the voltage on your 5V line is dropping. If you have other electronics connected to the line, the voltage eventually gets too low for everything to run.

Regulators also waste a good deal of your energy. If you have a 7.2 V battery pack going into a 5 V regulator, you are losing 30% of your energy right off the bat.

If this does not solve your problem, please provide more details about how you have everything connected.

- Jan