I've built a Parallax Boe-Bot which has servo driven wheels but have decided to move to Arduino and dc motors. I do not have specific motors in mind yet just some salvaged ones to play with for now. So my questions are:
1 - Is it worth getting a driver shield/kit or should I save the money and try something like a l293d on my breadboard?
2 - What shield/board do you recommend? I was considering the following:
A - Adafuit motor shield - I love their site and stuff always good, Has an Arduino library, has four H-bridges and can do two steppers which I am also interested in playing with
B - l298 Compact Motor Driver from Solarbotics - recommended by Frits, simple, I like the led indicators, can power Arduino
C - Robot Builder's Shield - cool idea combo driver/proto shield, abundance of three prong headers, can power Arduino
I have searched the forum but would love to hear what you guys are using and why!
EDIT: Can anyone recommend a good place to read up on motor and driver selection?
Full disclosure, yes, I am very much in favor of buying local --even if our “LMR local” happens to be quite global. Even without this fact, it is still a solid board. Everything one would need is there via female headers, solder pads and 3-pin “servo” connectors. There is room for a breadboard, screw terminals for motors power --everything is right where it should be. Beyond that, there is nothing else and thats a good thing. No crap, no gimmics, clean, every inch of the board is used and everything is in its place. The hardest thing to do is design a really perfect, simple thing. This is just that, simple and straight forward with no BS. A great board.
I think it’s not a good idea to pick a motor driver before you know what kind of motor you’re driving. And what kind of power source. Find out what motors, what they are rated at (Amps at run, stall, and voltage for that current), how you want to power, then figure out a motor driver suited to those parameters.
It would probably be good to look for gearmotors, that are rated to use a 6 to 12 volt power source, that have a stall current of less than an Amp. Some folks recommend 50 rpm to be an output speed, I like about double that for a more entertaining robot, though harder to control. 50 rpm would be about the same as the servos used for the BOE-Bot. For something like the above motors, an L293 or 754410 driver would work well. Even better are FET based drivers, like the LMD18200, though that requries a 12 volt supply.
Adafruit has some great boards, but the ability to switch things around, trying different drivers can be best on a prototyping board.
Thanks for the info. I also appreciate simplicity in design and like buying from someone here on LMR or even Adafruit who also give a lot to the community. Speaking of buying local have you found any where here in Mass you can buy anything? I am from the north shore even You-do-it never seems to have what I am looking for. By the way Walter is AWSOME! and I saw you copper and wood guy on I think on the Make blog. Nice work.
First thanks for the feedback. I was looking at something like a Tamiya gear motors maybe like this one. I like that you can change the gear ratios so I can adjust the speed range. Flexibility is really good as a beginner. I would like something faster that the boe-bot he really just puts around. Let me know if you have any better suggestions I am open to any that’s why I’m here!
I have found nothing. Then again, I am on the Cape so there is not really much of anything, let alone robot parts. I am sure there has got to be something in Boston, but I have not found it yet and at one point I found a “electronic surplus” place out in western mass, but again, never been there. If I order something that is non-Ebay, I pretty much stick to SparkFun and Pololu --both have awesome shipping times and you will get your stuff in 3 days with Priority shipping. HWV (HVW?) has most of the picaxe stuff one would want and even from Canada it is pretty quick. Other than that, and I hate to say it, Radio Shack has a few of the things you may need. --Ugg.
All the advice I’ve seen says don’t pick a motor controller first, but I figured that if you’re going to it might as well be one that costs $10. I have it running a tamiya twin gearbox right now (it is literally wandering the floor in front of me right now) at 1/5th speed (PWM value 50) and so far I have noticed no excessive heat coming from the motor controller. That being said I am 100% sure I’m going to burn out the motors eventually, but as has been pointed out by others pololu sells a drop-in replacement that is actually perfect for said motor controller. This is my plan for once I burn out these motors in the Tamiya gearbox.
Robot builder shield took a lot of frustration out of my build! Stacked two 754410 to double the motor amps. Don’t know if that’s a good idea in the long run.
What would be a good motor to pair with the Robot Builders Shield? The thing that i liked about the Tamiya was the ability to change the gear ratio to find the balance of torque to speed. I am not sure what ratio would be good for me right now. Thanks to everyone for their suggestions!
In general it is OK to stack the 754410 motor driver. You should check them carefully for heat during use. A heat sink may be advisable.
The only problem I can think of is that the traces on the RBS were designed with the current for a single 754410 in mind. They may be just fine with two, but it was probably not designed for it. If it works well, let us know about it.
