til311 demo in bonescript

til311.js

/*

Jeff Albrecht February 9, 2015

An experiment to display digits on a Texas Instruments TIL311. And practice my .js
    http://www.ti.com/lit/ds/symlink/til311.pdf
    
Not implemented in this til311 experiment 
    left and right decimal points
    configurable blank leading zeros
    PWM blanking input for brightness control

Notes / stuff to remember.
jha handy pins http://kilobaser.com/blog/2014-07-15-beaglebone-black-gpios
 oscon 2012 slides see 18 of 24
 
*/

var b = require('bonescript');

var latchA = "P8_46";
var latchB = "P8_42";
var latchC = "P8_38";
var latchD = "P8_34";
var strobeA = "P8_45";
var strobeB = "P8_41";
var strobeC = "P8_37";
var strobeD = "P8_33";
var til311pins = [latchA, latchB, latchC, latchD, strobeA, strobeB, strobeC, strobeD]; // order important. strobe lines calculated with offset of 4 in code

initPins();

// count and display from 0 to 9999
for (num = 0; num < 9999; num++) {
    // setInterval(displayNumber(num), 1000); // odd this did not pause a second between digits display.
    displayNumber(num); 
    sleep(1000);
}

// display a number on the four til311 elements. Pad with preceding 0s 
function displayNumber(number) {
    // console.log("number ", number);
    var arrayNumber = ("" + number).split("");
    // console.log("arrayNumber ", arrayNumber);

    var pad = 4 - arrayNumber.length;
    for (i = 0; i < pad; i++) {
        arrayNumber.splice(0, 0, '0');
    }

    var i = 0;
    for (digit in arrayNumber) {
        displayDigits(arrayNumber[digit], i++);
    }
}

// display a single digit on a single element where number to be displayed on place element position 0...3
function displayDigits(number, place) {
    // console.log("number ", number, "place ", place);
    b.digitalWrite(til311pins[place + 4], b.LOW); // strobe line for segment
    var bNumber = parseInt(number).toString(2);
    // console.log("bNumber ", bNumber);
    var digits = ("" + bNumber).split("");
    // console.log("digits ", digits);
    // console.log("length of digits array ", digits.length);

    if (digits.length < 4) { // left pad with '0' for an array length of exactly 4

        var pad = 4 - digits.length;
        // console.log("pad ", pad);
        for (i = 0; i < pad; i++) {
            digits.splice(0, 0, '0');
        }
        // console.log("digits ", digits);
    }

    // kludge! The bits are in a disadvantageous order for the for in loop. Swap the order of the array.
    var digitsFix = new Array(4);
    for (j = 3, k = 0; j >= 0; j--) {
        digitsFix[j] = digits[k++];
    }

    for (digit in digitsFix) {
        // console.log("charToState ", charToState(digits[digit]))
        b.digitalWrite(til311pins[digit], charToState(digitsFix[digit]));
    }
    b.digitalWrite(til311pins[place + 4], b.HIGH); // inhibit strobe
}

function initPins() {
    for (var j in til311pins) {
        b.pinMode(til311pins[j], b.OUTPUT);
        b.digitalWrite(til311pins[j], b.HIGH);
    }
}

// I should experiment with just using 1 or 0 in the line that calls this.
function charToState(bit) {
    // console.log("bit ", bit);
    if (bit !== '1') {
        return b.LOW;
    }
    else {
        return b.HIGH;
    }
}

// blocking delay
function sleep(delay) {
    var start = new Date().getTime();
    while (new Date().getTime() < start + delay);
}