I am quite new to the world of Arduino but have tried already a few things. I have an RC car with a 7.2V DC motor and one servo that I would like to control with arduino. My plan is to get the arduino motor shield from oomlout. That shield can control 2 big motors and 4 servos.
and also an ultrasonic range finder. I have a 3000mah 7.2V NiMh battery that I am planning to connect to the motor shield and also I am thinking to have a 9V battery supply to the Arduino. Do you know if I will have enough pins left to add more sensors or should I be looking at other shields? Initially I would like to add only one range finder at the front but at some point add one in the back too. And maybe look at accelerometers later on. But if I have used all my pins for the motor shield then what are my options?
thanks for the replies. Yes I have chosen the shield from the oomlout website, unfortunately I cant put the link in here. So from what you say I can put the sensors on the board underneath the motor shield. Excuse my ignorance but I have only played with the arduino board, I havent tried a shield yet and wasn't sure if practically I can plugin the sensors underneath any shield. Programmatically I should have no problems I am an experienced programmer.
Do you know the ratings of this motor (running and stall current)? I have a feeling that if this motor is anything like other r/c car motors running at 7.2VDC, its going to pull way more current than the L293 on that motor controller can supply. For example:
This motor may be similar to yours; it pulls 700mA while running, 21.2 amps stalled; the L293 on that shield can only supply 1.2A of current max (bridged mode, possibly needing a heatsink).
You need to find out -first- how much current your motor draws in both conditions; then you can decide on a motor driver. For higher current drivers, check out Pololu; there's also other options (if you can find a brushed DC motor controller for R/C cars - not airplanes - they can be fairly inexpensive)...
Hmmm ok I am a bit concerned now. Here is the link for the motor my rc car has
Hmm - that's kinda low on details...
Current Consumption at Best Efficiency: 7.9A at 7.2V
What that generally means is that at it will pull that much current while running, but that number is -not- the stall current, nor is it the "free running" (no load) current. The stall current is going to be much higher, and the no-load running current lower (probably around an amp or 2) - this sheet here is pretty close:
As you can see, you're probably looking at about 35A when stalled, so you want a controller that can at least handle that, and probably around 8-10A under normal running conditions.
You might be able to get away with something like this:
Especially if the dual outputs could be bridged together for more current handling (not sure if they can).
As you can see, there's a wide variety of choices out there - plus none of them are particularly cheap (some of them I consider inexpensive, given what they are doing - high-power h-bridges are easy to design).
Any other recommendations for a motor that I can use with this shield?
The kinds of motors that you use with that kind of shield (or more precisely, the L293 h-bridge chip) tend to look like this:
In other words, small hobby motors that may only pull several hundred milliamps when stalled; needless to say, these motors won't work for your application (unless you want to scale down the size of your vehicle)...
ok so this shield is for quite "small" in power motors. I am using arduino uno so ideally I would like to connect a motor shield on that. I will have a better look on your recommended controllers just in case I can connect them to arduino.
I had a look at my Tamiya TEU-101BK speed controller and it can output Max. continuous current at 60A Forward and 60A Reverse. Any ideas as to which shield I can use with Arduino?
I had a look at my Tamiya TEU-101BK speed controller and it can output Max. continuous current at 60A Forward and 60A Reverse. Any ideas as to which shield I can use with Arduino?
well..what do you need sheilds for ? if you want to use the motor controller you won't need a sheild just post a link to waht you want to control with the arduino and we'll get back to you and help
Yep you are right I found out a few minutes ago that I can just plug in the ESC on arduino like a normal servo and thats all there is to it. Hmmm sorry for the question but I just realized how much trickier I was going to make my project :).
