#!/usr/bin/python
    #--------------------------------------
    #  LCD Test Script
    #
    
    #--------------------------------------
    
    # The wiring for the LCD is as follows:
    # 1 : GND
    # 2 : 5V
    # 3 : Contrast (0-5V)*          -   Sets the LCD Contrast
    # 4 : RS (Register Select)      -   GPIO pin 26 - Physical pin 37
    # 5 : R/W (Read Write)          -   GROUND THIS PIN
    # 6 : Enable or Strobe          -   GPIO pin 19 - Physical pin 35
    # 7 : Data Bit 0             - NOT USED
    # 8 : Data Bit 1             - NOT USED
    # 9 : Data Bit 2             - NOT USED
    # 10: Data Bit 3             - NOT USED
    # 11: Data Bit 4                -   GPIO pin 13 - Physical pin 33
    # 12: Data Bit 5                -   GPIO pin 06 - Physical pin 31
    # 13: Data Bit 6                -   GPIO pin 05 - Physical pin 29
    # 14: Data Bit 7                -   GPIO pin 11 - Physical pin 23
    # 15: LCD Backlight             -   +5V**   
    # 16: LCD Backlight             -   GND
    
    #import
    import RPi.GPIO as GPIO
    import time
    
    # Define GPIO to LCD mapping
    LCD_RS = 26
    LCD_E  = 19
    LCD_D4 = 13
    LCD_D5 = 6
    LCD_D6 = 5
    LCD_D7 = 11
    
    
    # Define some device constants
    LCD_WIDTH = 40    # Maximum characters per line
    LCD_CHR = True
    LCD_CMD = False
    
    # Do I need to change line 2 address for 40 char display?
    LCD_LINE_1 = 0x80 # LCD RAM address for the 1st line
    LCD_LINE_2 = 0xC0 # LCD RAM address for the 2nd line
    
    # Timing constants
    E_PULSE = 0.0005
    E_DELAY = 0.0005
    
    def main():
      # Main program block
      
      GPIO.setwarnings(False)
      GPIO.setmode(GPIO.BCM)       # Use BCM GPIO numbers
      GPIO.setup(LCD_E, GPIO.OUT)  # E
      GPIO.setup(LCD_RS, GPIO.OUT) # RS
      GPIO.setup(LCD_D4, GPIO.OUT) # DB4
      GPIO.setup(LCD_D5, GPIO.OUT) # DB5
      GPIO.setup(LCD_D6, GPIO.OUT) # DB6
      GPIO.setup(LCD_D7, GPIO.OUT) # DB7
    
    
      # Initialise display
      lcd_init()
    
      while True:
    
        # Send some test
        lcd_string("Rasbperry Pi",LCD_LINE_1)
        lcd_string("40x2 LCD Test",LCD_LINE_2)
    
        time.sleep(3) # 3 second delay
    
        # Send some text
        lcd_string("Another Example :)",LCD_LINE_1)
        lcd_string("Now do your own",LCD_LINE_2)
    
        time.sleep(3)
    
    def lcd_init():
      # Initialise display
      lcd_byte(0x33,LCD_CMD) # 110011 Initialise
      lcd_byte(0x32,LCD_CMD) # 110010 Initialise
      lcd_byte(0x06,LCD_CMD) # 000110 Cursor move direction
      lcd_byte(0x0C,LCD_CMD) # 001100 Display On,Cursor Off, Blink Off
      lcd_byte(0x28,LCD_CMD) # 101000 Data length, number of lines, font size
      lcd_byte(0x01,LCD_CMD) # 000001 Clear display
      time.sleep(E_DELAY)
    
    def lcd_byte(bits, mode):
      # Send byte to data pins
      # bits = data
      # mode = True  for character
      #        False for command
    
      GPIO.output(LCD_RS, mode) # RS
    
      # High bits
      GPIO.output(LCD_D4, False)
      GPIO.output(LCD_D5, False)
      GPIO.output(LCD_D6, False)
      GPIO.output(LCD_D7, False)
      if bits&0x10==0x10:
        GPIO.output(LCD_D4, True)
      if bits&0x20==0x20:
        GPIO.output(LCD_D5, True)
      if bits&0x40==0x40:
        GPIO.output(LCD_D6, True)
      if bits&0x80==0x80:
        GPIO.output(LCD_D7, True)
    
      # Toggle 'Enable' pin
      lcd_toggle_enable()
    
      # Low bits
      GPIO.output(LCD_D4, False)
      GPIO.output(LCD_D5, False)
      GPIO.output(LCD_D6, False)
      GPIO.output(LCD_D7, False)
      if bits&0x01==0x01:
        GPIO.output(LCD_D4, True)
      if bits&0x02==0x02:
        GPIO.output(LCD_D5, True)
      if bits&0x04==0x04:
        GPIO.output(LCD_D6, True)
      if bits&0x08==0x08:
        GPIO.output(LCD_D7, True)
    
      # Toggle 'Enable' pin
      lcd_toggle_enable()
    
    def lcd_toggle_enable():
      # Toggle enable
      time.sleep(E_DELAY)
      GPIO.output(LCD_E, True)
      time.sleep(E_PULSE)
      GPIO.output(LCD_E, False)
      time.sleep(E_DELAY)

    def lcd_string(message,line):
      # Send string to display
    
    
    
    
      message = message.ljust(LCD_WIDTH," ")
    
      lcd_byte(line, LCD_CMD)
    
      for i in range(LCD_WIDTH):
        lcd_byte(ord(message[i]),LCD_CHR)
    
    if __name__ == '__main__':
    
      try:
        main()
      except KeyboardInterrupt:
        pass
      finally:
        lcd_byte(0x01, LCD_CMD)
        lcd_string("Goodbye!",LCD_LINE_1)
        GPIO.cleanup()