PinIO - Arduino pin management in javascript

This is a simple node.js library for controlling multiple arduino boards and groups of pins. This is intended to be a fairly low-level library that exposes an API which makes lower-level management of Arduino pins easier.

Beginners

Beginners with arduino would be better off looking at the excellent Johnny-Five Library: https://github.com/rwldrn/johnny-five. This library will abstract away a lot of pain points of dealing with pesky bits.

Installation

npm install pinio

Turning a LED on and off

var pinio = new (require('pinio')).Pinio()

pinio.on('ready', function(board) {

    var led = board.pins(11)
    led.output()
    led.high()

    setTimeout(function() {
        led.low()
    }, 2000)

})

Managing multiple boards

var pinio = new (require('pinio')).Pinio()

pinio.on('ready', function(first, second) {

    function turnOn(board, pin) {
        var led = board.pins(11)

        led.output()
        led.high()

        setTimeout(function() {
            led.low()
        }, 2000)
    }

    // Turn on an LED connected to the first board on port 11
    turnOn(first, 11)

    // Turn on an LED connected to the second board on port 10
    turnOn(second, 10)
})

Ping distance sensor

var pinio = new (require('pinio')).Pinio()

pinio.on('ready', function(board) {
    var ping = board.pins(13)

    setInterval(function() {
        ping.pulse()
    }, 500)

    ping.on('read', function(distance) {
        console.log('Distance is:', distance)
    })
})

Continuous Rotation Servo

The best way to position a continuous rotation servo is to set it to stopped, servo.write(90), then adjust the potentiometer until the servo no longer moves.

var pinio = new (require('pinio')).Pinio()

pinio.on('ready', function(board) {
    // "0" is full speed backwards.
    // "90" is stop,
    // "180" is full speed forward, 
    // TODO: I would like to make this -90, 0, 90

    var servo = board.pins(9)

    servo.mode('SERVO')

    var incrementer = 10
    var current = 90

    function setPosition() {
        servo.write(current)
        current += incrementer

        if (current >= 180 || current == 0)
            incrementer = 0 - incrementer

        setTimeout(setPosition, 500)
    }
    setPosition()

})

Shift Register

This example will implement a binary counter with 8 LEDs connected to a shift register on pins 2, 3, 4.

var pinio = new (require('pinio')).Pinio()

pinio.on('ready', function(board) {

    var dataPin = board.pins(2)
    var latchPin = board.pins(3)
    var clockPin = board.pins(4)

    dataPin.output()
    latchPin.output()
    clockPin.output()

    function shiftOut(clockPin, dataPin, value) {
        for (var mask = 128; mask > 0; mask = mask >> 1) {
            clockPin.low()
            dataPin[ value & mask ? 'high' : 'low' ]()
            clockPin.high()
        }
    }

    var counter = 0
    function loop() {

        if (counter >= 256)
            return

        latchPin.low()
        
        shiftOut(clockPin, dataPin, counter)

        latchPin.high()

        counter++
        setTimeout(loop, 100)
    }

    loop()
})

Potentiometer

Reads the value of a potentiometer on pin analog 0.

var pinio = new (require('pinio')).Pinio()

pinio.on('ready', function(board) {
    var pot = board.pins('A0')
    pot.read(function(val) {
        console.log(val)
    })
})

PWM Writing

Outputs a value using pulse-width modulation.

var pinio = new (require('pinio')).Pinio()

pinio.on('ready', function(board) {
    var control = board.pins(2)
    control.pwm(200)
})

Encoder

Detecting motor speed with an encoder. This example uses two PWM digital motors along with two optical encoders. This is similar to code I use in a personal robot.

var pinio = new (require('pinio')).Pinio()

pinio.on('ready', function(board) {

    board.firmata.setMaxListeners(100)

    var movement = [0, 0]

    var encoders = [

        // Encoder 1
        [2, 3],

        // Encoder 2
        [11, 12]
    ]

    function setupEncoder(pins, idx) {
        console.log('Setting up encoder:', idx, pins)
        var encodeA = board.pins(pins[0])
        var encodeB = board.pins(pins[1])

        function gotData(val) {
            movement[idx] += val
        }

        function startRead() {

            try {
                encodeA.mode('INPUT')
                encodeA.high()
                encodeB.mode('INPUT')
                encodeB.high()
            } catch(e) {
                console.log('Err ', e)
            }

            encodeA.read(gotData)
            encodeB.read(gotData)
        }
        startRead()
    }
    encoders.forEach(setupEncoder)

    setInterval(function() {
        console.log('Movement: ', movement)
    }, 300)
})

Board API

After initialization, the ready event will be fired with several board objects. A board object may create a pin wrapper with the following commands:

var myLed = board.pins(12)
var myGroup = board.pins(8, 9)

Pin API

Each pin group has shortcut methods.

• pin.output() - Sets the pin to output mode
• pin.high() - digital high
• pin.low() - digital low
• pin.pulse() - for things like IR sensors
• pin.write() - analog signals