dcmotor.js

var b = require('bonescript');
var MOTOR = 'P9_16';
var FORWARD = 'P9_18';
var BACKWARD = 'P9_22';
var POT = 'P9_36';
var BUTTON = 'P8_19'
var speed = 0;
var increment = 0.01;
var direction = 1;

b.pinMode(BUTTON, b.INPUT);
//b.pinMode(MOTOR, b.OUTPUT);
b.pinMode(FORWARD, b.OUTPUT);
b.pinMode(BACKWARD, b.OUTPUT);
b.digitalWrite(FORWARD, direction ? b.HIGH : b.LOW);
b.digitalWrite(BACKWARD, direction ? b.LOW : b.HIGH);
updateDuty();

function updateDuty() {
    b.analogWrite(MOTOR, speed, 60, scheduleNextUpdate);
}

function scheduleNextUpdate() {
    setTimeout(doRead, 20);
}

function doRead() {
    b.analogRead(POT, onRead);
}

function onRead(x) {
    if(!x.err) {
        speed = x.value;
    }
    doButtonRead();
}

function doButtonRead() {
    b.digitalRead(BUTTON, onButtonRead);
}

function onButtonRead(x) {
    if(!x.err) {
        if(direction != x.value) {
            direction = x.value;
            b.digitalWrite(FORWARD, direction ? b.HIGH : b.LOW);
            b.digitalWrite(BACKWARD, direction ? b.LOW : b.HIGH);
        }
    }
    updateDuty();
}