Let's Make Robots!

Pololu Micro Dual Serial Motor Controller (No Manual)

tc  
Vendor's Description: 

This tiny module can control two motors, 1 A peak each, and you can daisy-chain multiple units to control up to 62 motors with a single serial line. You can also order this controller including a color, printed manual, which is available as a PDF (292k pdf).

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Nebster's picture
well ive had a bit of trouble with mine. i copied that samplecood directly from there into my thingy and tried to send it to my arduino. it said that the file selection or something for the softwareserial is invalid or whateva. i know its probably really easy to fix but any ways can you give me a hand.
buhatkj's picture

Hey cowgod, I'm wondering if you have had troubles with these controllers with them being finicky or overly sensitive to electrical noise.  I bought the regular dual serial motor controller, http://www.pololu.com/catalog/product/376 

I've soldered caps across my motor leads, and finally got it connected right, but still it locks up after just a few seconds.  I've had the pololu forum guy trying to help me, but so far it's still no-go.  I want to get one that WORKS, do you have higher confidence in these micro ones, or  was it pretty hard to get it running?

:-)

TheCowGod's picture

It's funny you should ask, because I've actually been struggling with some sort of problem like this lately, on my BullyBot. I had originally set it up with the Pololu Low Voltage Dual Serial Motor Controller, because I was using a Tamiya dual gearbox with the stock Mabuchi FA-130 motors. It worked fine in testing, but when I soldered everything up and assembled the robot, the motors would pulse for a fraction of a second (along with the indicator LED on the controller), and then they'd stop, and all the lights on the controller would shut down. I decided the motors must be overloading the controller, so I replaced the motors with the RM3 replacements that are supposed to match well with the Micro. I had a spare Micro controller too, so now I'm running a uDSMC with the RM3's, but I'm seeing the same behavior. If I just measure the outputs with a voltmeter, they go high and low as expected, but when I touch the wire to the motor's leads, it pulses for a moment and then stops, and I no longer see any voltage.

So no, I wouldn't necessarily say they're foolproof, although the one I've got in my Little Drum Machine is working flawlessly (though that one too took some fiddling to get working originally). I'm not sure if my problem on BullyBot is due to over current, or noise -- I've got one 10uF capacitor across the leads of each motor, but maybe I should try adding caps from each lead to the motor casing as well.

Dan

I have just purchased one of these motor controllers, and I also purchased two drive motors (http://www.robotshop.ca/home/products/robot-parts/motors/gear-motors/spur-gearmotors/banebots-30-1-25mm-spur-motor-ff180.html) for the controller to power.

 However, the stall current on that motor is 6.7 amps - far higher than the maximum output of the controller. Although the robot I'm making is light enough that it probably won't reach that under normal operation, any resistance it meets could pose a problem. If the motor were to draw more than 1A, what would happen to the controller? Would it be neccessary and/or difficult to build a protection circuit?

TheCowGod's picture

Late response, but I just came across this posting. From what I've read, the motor controller has good over-current and over-temperature protection -- it will just shut down until you reset it by unplugging it. But a motor that stalls at 6.7 amps probably won't run on this controller at all, because motors tend to draw a lot of current when starting up too, usually close to the stall current. But it shouldn't hurt anything to try it out and see.

Dan

jgillick's picture
I really want to get into Adruino, but haven't ordered the parts yet -- but I do have a Picaxe set.  For some reason I cannot get this motor controller to work wth the Picaxe.  Have you tried or seen anybody who has?  Thanks.
TheOther1's picture

Maybe this will help:

http://www.pololu.com/docs/0J2/4

 

jgillick's picture
Ha ha, I know Assembly language even less. :)  I was trying to do it with Picaxe BASIC, but it wasn't working.  I'm going to order an Adruino board today and we'll see if that works.
TheOther1's picture

In the code, if you are using Linux,
#include <softwareserial.h>
Must read:
#include <SoftwareSerial.h>
because Linux is case sensitive.

Are these digital or analog pins?
byte motor_controller_pin = 3;
byte motor_controller_reset_pin = 4;


There is no connection to this pin, at all?
// for rx on all unidirectional software serial objects
byte unused_pin = 10;

Thanks!
TheCowGod's picture

Interestingly enough, I am using Linux, and that code was copied and pasted straight out of my .pde file, which works just fine. But I just checked, and you're right, the actual SoftwareSerial.h file on disk is capitalized. I'm not sure why it works :) The Arduino IDE software must be doing some clever reprocessing.

And yeah, as I said in my email, pins 3 and 4 in my code refer to digital I/O pins (though there's no reason why you couldn't use the analog pins too, since those can be used as digital pins as well -- you'd just need to refer to them as 14-19 rather than 0-5). But it's just serial communication, and an output at that, so there's no need to use a pin with analog input capability.

And yes, pin 10 is not connected to anything -- the SoftwareSerial constructor wants you to specify both an rx pin and a tx pin, but I only needed the tx pin, so I just used some unused pin as my rx pin for the SoftwareSerial() initialization. 

Dan