Pololu Micro Dual Serial Motor controller - review and example code
Dennis Ferron
Posts: 480
I'm pleased to see that Parallax is now carrying this device. When I built a robot last year Basic Stamp 1 USB stick, I had to make two orders; one from Parallax for the Basic Stamp and another from Pololu.com for the motor controller. Being able to order both from Parallax will be much more convenient.
Having had some bad experiences with motor controllers from other companies, the Pololu product came as a great surprise to me. It has a straightforward command protocol and was easy to use. The ability to put multiple controllers on the same serial lines is a nice touch, too, but I haven't tried that out yet.
I used the motor controller on a small robot named "Dobby". The motors I was using were 2.4 volt pager motors drawing about 150 mA each, but my battery was 7.4 volts. I ran the motors at a very narrow pulse width to make up for the difference in voltage; still the motor controller did get too hot after extended use. It apparently has a good thermal shutdown protection though because I overheated it many times and it always came back working again after it cooled. I would recommend attaching a small heatsink if you are going to run the motors for long periods of time. I superglued a small half-square inch piece of aluminum to the chips and it took care of the problem. Later I switched to a 4.8 volt battery pack as well, and the thermal issue seems to be resolved.
One thing to note is that the motor controller only does the PWM at 500 cycles per second, which is a somewhat lower frequency than I expected - AFAIK 500 Hz could cause unwelcome vibration in an industrial motor - but it seems to pose no problem for toy motors. I'm getting more than an hour of running time for the robot off just four AAA NiMH batteries, so I can't complain!
The example code is for the Basic Stamp 1, and shows some simple commands for making a differential drive robot go forward, turn, etc., using the dual serial motor controller.
Having had some bad experiences with motor controllers from other companies, the Pololu product came as a great surprise to me. It has a straightforward command protocol and was easy to use. The ability to put multiple controllers on the same serial lines is a nice touch, too, but I haven't tried that out yet.
I used the motor controller on a small robot named "Dobby". The motors I was using were 2.4 volt pager motors drawing about 150 mA each, but my battery was 7.4 volts. I ran the motors at a very narrow pulse width to make up for the difference in voltage; still the motor controller did get too hot after extended use. It apparently has a good thermal shutdown protection though because I overheated it many times and it always came back working again after it cooled. I would recommend attaching a small heatsink if you are going to run the motors for long periods of time. I superglued a small half-square inch piece of aluminum to the chips and it took care of the problem. Later I switched to a 4.8 volt battery pack as well, and the thermal issue seems to be resolved.
One thing to note is that the motor controller only does the PWM at 500 cycles per second, which is a somewhat lower frequency than I expected - AFAIK 500 Hz could cause unwelcome vibration in an industrial motor - but it seems to pose no problem for toy motors. I'm getting more than an hour of running time for the robot off just four AAA NiMH batteries, so I can't complain!
The example code is for the Basic Stamp 1, and shows some simple commands for making a differential drive robot go forward, turn, etc., using the dual serial motor controller.
