Drive a Stepper Motor with an AVR Microprocessor

Step 8 The End

So what did I learn? Driving a stepper motor with an AVR (and an H-bridge chip) is pretty easy, even in the "fancy" half-stepping mode.

Not sure what I'll do with the little stepper motors just yet, though. Any suggestions?

Comments

[uberdum05]

An idea for the stepper motor, use two of them in a small robot as the drive motors to do fancy precision moves :)

[TobiasPl]

I really like this tutorial! Very easy to follow, but I have a questions left: Lets say the sequence is BLUE BLACK RED YELLOW and RED is set to 5V, all others to 0V. Now I turn off the current and later on, I turn it on again but the IC now again starts with BLUE at 5V instead of RED. What will happen?

[The Real Elliot]

It doesn't really matter where in the cycle you start, although the motor might turn backwards one step before it gets going in the right direction. So in your example, you stopped the motor with RED energized. If you then went back to BLACK, it would take one step backwards so that it was lined up with BLACK. At that point, you'd continue the cycle either to BLUE or RED, and that would determine the direction that the motor rotated. As for BLUE... It would be 50/50 whether it goes clockwise or counter-clockwise. Try it and see? Repeat it like 10 times or so. Regardless, it won't hurt the motor.

[TurboTronix]

I want to use this setup to open and close a valve (for water current)...

[The Real Elliot]

Are you in the US? If so, you probably want a "sprinkler valve" instead. They're like $10-15 at Home Depot or many hardware stores.

Or a dishwasher repair place may have a similar solenoid-driven water valve for use in dishwashers.

Unless your application is very strange, buying a purpose-built solenoid valve is probably a lot easier, cheaper, and more reliable.

If your application is very strange, you may need more torque to open/close the valve than a direct-driven stepper motor can provide. You may need a gearbox.

[Herodotus]

I went to the hardware today (Sydney, Australia) to get a solenoid garden watering valve to use on my yacht. All seemed to be either mains power or 24 volt DC - no 12 volt available. Anypne know where I can get a 12 volt DC one please?

[TurboTronix]

It is for a school project. I changed it a little though. Now all I need is to use your setup but with some sort of a switch that will allow me to choose the spinning direction. I tried adding a simple ON/OFF switch to one of the ATTINY2313 chip without success. I ordered the H-bridge and should be getting it shortly. Do you know by any chance how should your code look with an input?

[The Real Elliot]

Setting up a button-press input with the AVR (or any microcontroller) is a classic problem. Basically, you can configure a pin as an input pin, and then you use the button to send either a high or low voltage to that pin.

There's some extra tricks because usually switches "bounce" back and forth between on and off as you press them down. You're gonna want to debounce the switch.

This PDF on debouncing is pretty good. And google around to find more examples.

[TurboTronix]

ya i guess you are right... A selenoid would be a better idea. I saw an electrical one so basically it would be a simple ON/OFF switch rather then spin.