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- #!/usr/bin/python
- #
- # HD44780 LCD Test Script for
- # Raspberry Pi
- #
- # Author : Matt Hawkins
- # Site : http://www.raspberrypi-spy.co.uk
- #
- # Date : 03/08/2012
- #
- # The wiring for the LCD is as follows:
- # 1 : GND
- # 2 : 5V
- # 3 : Contrast (0-5V)*
- # 4 : RS (Register Select)
- # 5 : R/W (Read Write) - GROUND THIS PIN
- # 6 : Enable or Strobe
- # 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
- # 12: Data Bit 5
- # 13: Data Bit 6
- # 14: Data Bit 7
- # 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
- LED_ON = 15
- # Define some device constants
- LCD_WIDTH = 16 # Maximum characters per line
- LCD_CHR = True
- LCD_CMD = False
- 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 = 0.00005
- E_DELAY = 0.00005
- def main():
- # Main program block
- # Initialise display
- lcd_init()
- # Toggle backlight on-off-on
- GPIO.output(LED_ON, True)
- time.sleep(1)
- GPIO.output(LED_ON, False)
- time.sleep(1)
- GPIO.output(LED_ON, True)
- time.sleep(1)
- # Send some centred test
- lcd_byte(LCD_LINE_1, LCD_CMD)
- lcd_string("Rasbperry Pi",2)
- lcd_byte(LCD_LINE_2, LCD_CMD)
- lcd_string("Model B",2)
- time.sleep(3) # 3 second delay
- # Send some left justified text
- lcd_byte(LCD_LINE_1, LCD_CMD)
- lcd_string("1234567890123456",1)
- lcd_byte(LCD_LINE_2, LCD_CMD)
- lcd_string("abcdefghijklmnop",1)
- time.sleep(3) # 3 second delay
- # Send some right justified text
- lcd_byte(LCD_LINE_1, LCD_CMD)
- lcd_string("Raspberrypi-spy",3)
- lcd_byte(LCD_LINE_2, LCD_CMD)
- lcd_string(".co.uk",3)
- time.sleep(30)
- # Turn off backlight
- GPIO.output(LED_ON, False)
- def lcd_init():
- 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
- GPIO.setup(LED_ON, GPIO.OUT) # Backlight enable
- # Initialise display
- lcd_byte(0x33,LCD_CMD)
- lcd_byte(0x32,LCD_CMD)
- lcd_byte(0x28,LCD_CMD)
- lcd_byte(0x0C,LCD_CMD)
- lcd_byte(0x06,LCD_CMD)
- lcd_byte(0x01,LCD_CMD)
- def lcd_string(message,style):
- # Send string to display
- # style=1 Left justified
- # style=2 Centred
- # style=3 Right justified
- if style==1:
- message = message.ljust(LCD_WIDTH," ")
- elif style==2:
- message = message.center(LCD_WIDTH," ")
- elif style==3:
- message = message.rjust(LCD_WIDTH," ")
- for i in range(LCD_WIDTH):
- lcd_byte(ord(message[i]),LCD_CHR)
- 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
- time.sleep(E_DELAY)
- GPIO.output(LCD_E, True)
- time.sleep(E_PULSE)
- GPIO.output(LCD_E, False)
- time.sleep(E_DELAY)
- # 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
- time.sleep(E_DELAY)
- GPIO.output(LCD_E, True)
- time.sleep(E_PULSE)
- GPIO.output(LCD_E, False)
- time.sleep(E_DELAY)
- if __name__ == '__main__':
- main()
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