Project 21.js

var b = require('bonescript');

var my_string = "BeagleBone Black Evil Genius";

var lcd_pin_D4 = "P8_11";
var lcd_pin_D5 = "P8_12";
var lcd_pin_D6 = "P8_13";
var lcd_pin_D7 = "P8_14";
var lcd_rs = "P8_15";
var lcd_e = "P8_16";

b.pinMode(lcd_pin_D4, b.OUTPUT);
b.pinMode(lcd_pin_D5, b.OUTPUT);
b.pinMode(lcd_pin_D6, b.OUTPUT);
b.pinMode(lcd_pin_D7, b.OUTPUT);
b.pinMode(lcd_rs, b.OUTPUT);
b.pinMode(lcd_e, b.OUTPUT);

b.digitalWrite(lcd_pin_D4, b.LOW);
b.digitalWrite(lcd_pin_D5, b.LOW);
b.digitalWrite(lcd_pin_D6, b.LOW);
b.digitalWrite(lcd_pin_D7, b.LOW);
b.digitalWrite(lcd_rs, b.LOW);
b.digitalWrite(lcd_e, b.LOW);


LCD_init( function () { write_string_to_lcd(my_string, function() {} ); } );

function LCD_init(callback) {
    b.digitalWrite(lcd_e, b.LOW);
    var i = 0;
    var steps = [
        function(){ setTimeout(next, 50); },
        function(){ write4bits(0x03, next); },
        function(){ setTimeout(next, 5); },

        function(){ write4bits(0x03, next); },
        function(){ setTimeout(next, 5); },

        function(){ write4bits(0x03, next); },
        function(){ setTimeout(next, 2); },
        function(){ write4bits(0x02, next); },
        function(){ write_bits_to_lcd(0x28, true, next); },
        function(){ write_bits_to_lcd(0x0C, true, next); },
        function(){ write_bits_to_lcd(0x06, true, next); },
        function(){ write_bits_to_lcd(0x01, true, next); },
        function(){ write_string_to_lcd('\x7escreen init', next ); },
        function(){ setTimeout(next, 800); },
        function(){ write_bits_to_lcd(0x01, true, callback); }
        ];
    next();
    function next() {
        i++;
        steps[i-1]();
    }
}
function write_bits_to_lcd(value, command_or_character, callback) {
    var value_left = (value >> 4);
    if (command_or_character === true) b.digitalWrite(lcd_rs, b.LOW);
        else b.digitalWrite(lcd_rs, b.HIGH);
    write4bits(value_left, function() { write4bits(value, callback); } );
}
function write4bits(value, callback) {
    if((value >> 3) & 0x01) b.digitalWrite(lcd_pin_D7, b.HIGH);
        else b.digitalWrite(lcd_pin_D7, b.LOW);
    if((value >> 2) & 0x01) b.digitalWrite(lcd_pin_D6, b.HIGH);
        else b.digitalWrite(lcd_pin_D6, b.LOW);
    if((value >> 1) & 0x01) b.digitalWrite(lcd_pin_D5, b.HIGH);
        else b.digitalWrite(lcd_pin_D5, b.LOW);
    if(value & 0x01) b.digitalWrite(lcd_pin_D4, b.HIGH);
        else b.digitalWrite(lcd_pin_D4, b.LOW);
    b.digitalWrite(lcd_e, b.HIGH);
    b.digitalWrite(lcd_e, b.LOW);
    callback();
}
function write_string_to_lcd(s, callback) {
    var s_length = s.length;
    if (s_length > 32) {
        write_string_to_lcd_two_lines('ERROR:', 'String too long', callback);
        return;
    }
    if (s_length < 17) {
        write_bits_to_lcd(0x80, true, function () {
 helper_lcd_display_string(s, callback ); } );
    } else {
        write_string_to_lcd_two_lines(s.slice(0,16),
 s.slice(16, s_length), callback);
    }
}
function write_string_to_lcd_two_lines(line1, line2, callback) {
    write_bits_to_lcd(0x80, true, function () {
 helper_lcd_display_string(line1, function() {second_line();} ); } );
    function second_line() {
        write_bits_to_lcd(0xC0, true, function () {
 helper_lcd_display_string(line2, callback ); } );
    }
}
function helper_lcd_display_string(s, callback) {
    if (s.length === 0) {
        callback();
    } else {
        write_bits_to_lcd(s.charCodeAt(0), false, function() {helper_lcd_display_string(s.slice(1), callback);} );
    }
}