Wednesday, June 8, 2011

Stepper motor references

Recently I have been playing around with stepper motors on my Arduino. (An overview of one project is on my photography blog.) Here's a list of online resources I've found helpful in my education:

How to wire a stepper motor has a good overview of the different types of steppers and how to identify the wires on an unknown motor.

Circuits for Unipolar motors on the Arduino site uses a ULN2003 or ULN2004 chip. One circuit has a couple resistors and a diode to allow two pin control of the motor. The other uses only the chip but requires four pins. I built the two pin configuration and it worked flawlessly. Note: the ULN2003 will only source up to 500mA. Higher current motors will cause its magic smoke to escape.

Stepper motor controller circuit uses two logic chips, four each of resistors, transistors and diodes and is controlled by two pins. Since it uses discrete components, it's easily modified for higher current motors than the ULN2003/ULN2004 can support. I haven't built this one, but have the components to do so in the future.

The 28BYJ-48 stepper motor is a really cheap, high resolution stepper motor that comes in both 5V and 12V ratings. Not sure how reliable it is, but so far in my experiments it has worked well. It has a 64:1 reduction gear head built into it, so it is pretty high torque for the current draw (I think it's spec'd to be around 250ma) and a whole lot of steps per revolution.

Stepper Motors and Control is a good overview tutorial. It includes logic charts for different ways of driving stepper motors for different purposes: lower power, higher torque and higher number of steps. It also talks about identifying different types of steppers and how to select a current limiting resistor.

I'll update this list if I find anything else that seems like it'd be good to have here.
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