johnny-five/eg/seven-segment.js

Firmata based Arduino Programming Framework.

/**
 * This example uses a single seven-segment display (common anode) and a
 * 74HC595 shift register. See docs/breadboard/seven-segment.png for wiring.
 */
var five = require("../lib/johnny-five.js"),
    board;

board = new five.Board();

board.on("ready", function() {
  var isCommonAnode, digits, segments, sr, led, i;

  /*

    This assumes the segments are as follows:

       A
      ---
    F | | B
      --- <---- G
    E | | C
      ---
       D  o DP

   */

  isCommonAnode = true;
  digits = [];

  //                    .GFEDCBA
  digits[0] = parseInt( "00111111", 2 );  // 0
  digits[1] = parseInt( "00000110", 2 );  // 1
  digits[2] = parseInt( "01011011", 2 );  // 2
  digits[3] = parseInt( "01001111", 2 );  // 3
  digits[4] = parseInt( "01100110", 2 );  // 4
  digits[5] = parseInt( "01101101", 2 );  // 5
  digits[6] = parseInt( "01111101", 2 );  // 6
  digits[7] = parseInt( "00000111", 2 );  // 7
  digits[8] = parseInt( "01111111", 2 );  // 8
  digits[9] = parseInt( "01101111", 2 );  // 9

  segments = {
    //              .GFEDCBA
    a   : parseInt( "00000001", 2 ),
    b   : parseInt( "00000010", 2 ),
    c   : parseInt( "00000100", 2 ),
    d   : parseInt( "00001000", 2 ),
    e   : parseInt( "00010000", 2 ),
    f   : parseInt( "00100000", 2 ),
    g   : parseInt( "01000000", 2 ),
    dp  : parseInt( "10000000", 2 )
  };

  sr = new five.ShiftRegister({
    pins: {
      data: 2,
      clock: 3,
      latch: 4
    }
  });

  led = new five.Led(5);

  function invert( num ) {
    return ((~num << 24) >> 24) & 255;
  }

  sr.digit = function( num ) {
    sr.clear();

    sr.send(
      isCommonAnode ? invert(digits[num]) : digits[num]
    );
  };

  sr.segment = function( s ) {
    sr.clear();

    sr.send(
      isCommonAnode ? invert(segments[s]) : segments[s]
    );
  };

  sr.clear = function() {
    sr.send(
      isCommonAnode ? 255 : 0
    );
  };

  i = 9;

  function next() {
    led.stop();
    sr.digit( i-- );

    if ( i < 0 ) {
      i = 9;
      led.strobe(50);
      setTimeout( next, 2000 );
    } else {
      setTimeout( next, 1000 );
    }
  }

  next();
});