LCD proof of concept for johnny-five

lcd.js

// Wire up LCD as described here:
// http://learn.adafruit.com/character-lcds/overview

var five = require("johnny-five"),
    board, lcd;

board = new five.Board();

board.on("ready", function() {

  lcd = {
    rsPin: 7, // LCD pin 4
    // rwPin:, // LCD pin 5, only needed when reading from display
    enPin: 8, // LCD pin 6
    dataPins: [12, 11, 10, 9] // D7 to D4. LCD pins 14, 13, 12, 11
  };

  var sleep = function(milliSeconds) {
    var startTime = new Date().getTime();
    while (new Date().getTime() < startTime + milliSeconds);
  };

  var highLowFromBinary = function(number) {
    return number === 1 ? board.firmata.HIGH : board.firmata.LOW;
  };

  var sendCommand = function(command) {
    board.digitalWrite(lcd.dataPins[0], highLowFromBinary(command[0]));
    board.digitalWrite(lcd.dataPins[1], highLowFromBinary(command[1]));
    board.digitalWrite(lcd.dataPins[2], highLowFromBinary(command[2]));
    board.digitalWrite(lcd.dataPins[3], highLowFromBinary(command[3]));

    // Pulse the EN pin to send first nibble
    board.digitalWrite(lcd.enPin, board.firmata.HIGH);
    board.digitalWrite(lcd.enPin, board.firmata.LOW);

    board.digitalWrite(lcd.dataPins[0], highLowFromBinary(command[4]));
    board.digitalWrite(lcd.dataPins[1], highLowFromBinary(command[5]));
    board.digitalWrite(lcd.dataPins[2], highLowFromBinary(command[6]));
    board.digitalWrite(lcd.dataPins[3], highLowFromBinary(command[7]));

    // Pulse the EN pin to send second nibble
    board.digitalWrite(lcd.enPin, board.firmata.HIGH);
    board.digitalWrite(lcd.enPin, board.firmata.LOW);
  };

  var writeMessage = function() {
    board.digitalWrite(lcd.rsPin, board.firmata.LOW);
    sendCommand([0,0,0,0,0,0,0,1]);

    board.digitalWrite(lcd.rsPin, board.firmata.HIGH);
    sendCommand([0,1,0,0,1,0,1,0]);
    sleep(200);
    sendCommand([0,1,1,0,1,1,1,1]);
    sleep(200);
    sendCommand([0,1,1,0,1,0,0,0]);
    sleep(200);
    sendCommand([0,1,1,0,1,1,1,0]);
    sleep(200);
    sendCommand([0,1,1,0,1,1,1,0]);
    sleep(200);
    sendCommand([0,1,1,1,1,0,0,1]);
    sleep(200);
    sendCommand([0,0,1,0,1,1,0,1]);
    sleep(200);
    sendCommand([0,1,1,0,0,1,1,0]);
    sleep(200);
    sendCommand([0,1,1,0,1,0,0,1]);
    sleep(200);
    sendCommand([0,1,1,1,0,1,1,0]);
    sleep(200);
    sendCommand([0,1,1,0,0,1,0,1]);

    board.digitalWrite(lcd.rsPin, board.firmata.LOW);
  };

  // RS to low (for command mode), EN to low to start
  board.digitalWrite(lcd.rsPin, board.firmata.LOW);
  board.digitalWrite(lcd.enPin, board.firmata.LOW);

  // Switch to 4-bit mode
  board.digitalWrite(lcd.dataPins[0], board.firmata.LOW);
  board.digitalWrite(lcd.dataPins[1], board.firmata.LOW);
  board.digitalWrite(lcd.dataPins[2], board.firmata.HIGH);
  board.digitalWrite(lcd.dataPins[3], board.firmata.LOW);
  board.digitalWrite(lcd.enPin, board.firmata.HIGH);
  board.digitalWrite(lcd.enPin, board.firmata.LOW);
  // Set to two-line mode
  sendCommand([0,0,1,0,1,0,0,0]);

  // Clear display and turn it on
  sendCommand([0,0,0,0,0,0,0,1]);
  sendCommand([0,0,0,0,1,1,1,1]);

  // Write some text
  writeMessage();

});

Oh, and the big advantage of the I2C solution is that you can get away with only using 2 pins on the arduino. The straight connection I'm using requires 6 digital pins. But again: So much extra soldering with I2C...

I think this is the LiquidCrystal API source: https://github.com/arduino/Arduino/tree/master/libraries/LiquidCrystal. Thanks so much for the writeup! This is hugely helpful and I'll be adding an LCD to my next order :)

This is brilliant — I must have this LCD somewhere as well...

Also, I wrote a little function for converting chars to their full binary sequence.

@rmurphy, Thanks for the link, I'm certain it will come in handy even though I don't speak C at all. You should definitely add an lcd to your next order. If you look in the PDFs you will see that you can create your own 5x8 pixel graphics to use as characters. I want to make bar charts/sparklines and whatnot (or an equalizer?)

@rwaldron, Can I see your function? I don't wan't to write any code I don't have to. :)

@haugstrup I opened an issue on johnny-five related to this, maybe we can move the implementation discussion there for easier collaboration?

Sounds good :)

Also, see https://gist.github.com/3185390#L34 for turning an integer into a sequence of binary digits, which may be useful.