Stepper Motor Module

Note: For a more in-depth look at Stepper Motors, see the Stepper Motor page - this page deals with the stepper motor module.

You can see the source for the StepperMotor (About Modules) module here.

Wiring Up

See the Stepper Motor page for more information on wiring. For this module you need to have attached your stepper motor driver to any 4 IO pins on Espruino.

Simple Usage

Just create an instance of StepperMotor and pass in an array of pins for each of the 4 stepper motor coils. For most stepper motor & driver combinations that you would buy, just supply the 4 pins in the order they are numbered on the driver board (1 to 4).

If your stepper motor doesn't move smoothly, you may need experiment with different orderings of the pins.

When initialised you can call moveTo on it to move the motor.

var StepperMotor = require("StepperMotor");

var motor = new StepperMotor({
  pins:[B10,B13,B14,B15]
});

setWatch(function() {
  motor.moveTo(motor.getPosition()+100);
}, BTN, {repeat:true, edge:"rising", debounce:50});

Advanced usage

If your motor is stepping too fast or slow then you can set stepsPerSec to a differen number (default is 100):

var motor = new StepperMotor({
  pins : [B10,B13,B14,B15],
  stepsPerSec : 50,
});

You can also choose the speed at which you wish to move the motor by specifying it in moveTo - you can also have a callback function when the position is reached, and by specitying true for turnOff (the very last argument) you can turn the motor off when finished:

// Move to step 100 in 1 second
motor.moveTo(100, 1000, function() {
  // Move back to step 0 in 0.5 seconds
  motor.moveTo(0, 500, function() {
    // we're done!
    console.log("Done!");
  }, true);  
});

If you want to use a different step pattern or your motor driver uses different polarities for some pins, you can set these on initialisation.

It may also be important to set the output pattern used to turn the stepper motor completely off.

For instance the following sets an 8 step pattern.

var motor = new StepperMotor({
  pins : [B10,B13,B14,B15],
  stepsPerSec : 100, /* default */
  pattern :  [0b0001,0b0011,0b0010,0b0110,0b0100,0b1100,0b1000,0b1001],
  offpattern : 0b0000, /* default */
  onstep : undefined, /* default - or specify a function to be called once per step */
});

Reference

// Set the current position to be home (0)
StepperMotor.prototype.setHome = function () { ... }

// Get the current position
StepperMotor.prototype.getPosition = function () { ... }

// Stop movement, and if `turnOff` is true turn off the coils
StepperMotor.prototype.stop = function (turnOff) { ... }

/* Move to a specific position in the time given. If no time
is given, it will be calculated based on this.stepsPerSec.
`callback` will be called when the movement is complete,
and if `turnOff` is true the coils will be turned off
*/
StepperMotor.prototype.moveTo = function (pos, milliseconds, callback, turnOff) { ... }

// Create a new stepper instance
function (obj) { ... }

Using

(No tutorials are available yet)

Buying

You can get all kinds of stepper motors and drivers, however the small 5V geared stepper motors on eBay are amazingly cheap, and very easy to wire up to Espruino.