#!/usr/bin/perl
# Example program which writes to the I2C LCD at address 0x3f.  This was 
# a direct port of the program published by Matt Hawkins on the site
# www.raspberrypi-spy.co.uk.  Port performed by Steve Stock.   
#
use strict;
use warnings;
use Time::HiRes ('usleep');
use Device::SMBus;

my $I2C_ADDR=0x3f;
my $DEVICE_PATH = '/dev/i2c-1';
my $dev = Device::SMBus->new(I2CBusDevicePath => $DEVICE_PATH,
  I2CDeviceAddress => $I2C_ADDR);
my $LCD_WIDTH = 16;
my $LCD_CHR=1;
my $LCD_CMD=0;
my $FILL_CHAR=" ";

my $LCD_LINE_1=0x80;
my $LCD_LINE_2=0xc0;
my $LCD_LINE_3=0x94;
my $LCD_LINE_4=0xd4;

my $LCD_BACKLIGHT=0x08;
my $LCD_BACKLIGHT_OFF=0x00;

my $ENABLE=0b00000100;

my $E_PULSE=500;
my $E_DELAY=500;

sub lcd_toggle_enable {
  my ($bits)=@_;
  usleep($E_PULSE);
  my $rc = $dev->writeByteData(0x00,$bits | $ENABLE);
  $rc = $dev->writeByteData(0x00,$bits & ~$ENABLE);
}


sub lcd_byte {
  my ($bits,$mode) = @_;
  my $bits_high=0;my $bits_low=0;
  $bits_high = $mode | ($bits & 0xf0) | $LCD_BACKLIGHT;
  $bits_low = $mode | (($bits << 4) & 0xf0) | $LCD_BACKLIGHT;
  my $rc = $dev->writeByteData(0x00,$bits_high);  
  lcd_toggle_enable($bits_high);
  $rc = $dev->writeByteData(0x00,$bits_low);
  lcd_toggle_enable($bits_low);
  usleep($E_PULSE);
}

sub lcd_init {
  lcd_byte(0x33,$LCD_CMD);
  lcd_byte(0x32,$LCD_CMD);
  lcd_byte(0x06,$LCD_CMD);
  lcd_byte(0x0c,$LCD_CMD);
  lcd_byte(0x28,$LCD_CMD);
  lcd_byte(0x01,$LCD_CMD);
  usleep($E_PULSE);
}

sub lcd_string {
  my ($message, $line) = @_;
  lcd_byte($line, $LCD_CMD);
  for (0..$LCD_WIDTH) {$message=$message.$FILL_CHAR};
  for (my $i=0;$i<($LCD_WIDTH);$i++) {lcd_byte(ord(substr($message,$i,1)),$LCD_CHR);}
}  

# MAIN
while (1==1) {
  lcd_init(); 
  lcd_string("RPiSpy         <",$LCD_LINE_1);
  lcd_string("I2C LCD        <",$LCD_LINE_2);
  sleep(5);
  lcd_string(">         RPiSpy",$LCD_LINE_1);
  lcd_string(">        I2C LCD",$LCD_LINE_2);
  sleep(5);
}