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import RPi.GPIO as GPIO
from random import sample
import string
import time
class LCD1602:
# Define GPIO to LCD mapping
LCD_RS = 14
LCD_E = 15
LCD_D4 = 17
LCD_D5 = 18
LCD_D6 = 27
LCD_D7 = 22
# 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 = 0.0005
E_DELAY = 0.0005
def __init__(self):
# Main program block
GPIO.setwarnings(False)
GPIO.setmode(GPIO.BCM) # Use BCM GPIO numbers
GPIO.setup(self.LCD_E, GPIO.OUT) # E
GPIO.setup(self.LCD_RS, GPIO.OUT) # RS
GPIO.setup(self.LCD_D4, GPIO.OUT) # DB4
GPIO.setup(self.LCD_D5, GPIO.OUT) # DB5
GPIO.setup(self.LCD_D6, GPIO.OUT) # DB6
GPIO.setup(self.LCD_D7, GPIO.OUT) # DB7
# Initialise display
self.lcd_init()
def lcd_init(self):
# Initialise display
self.lcd_byte(0x33, self.LCD_CMD) # 110011 Initialise
self.lcd_byte(0x32, self.LCD_CMD) # 110010 Initialise
self.lcd_byte(0x06, self.LCD_CMD) # 000110 Cursor move direction
self.lcd_byte(0x0C, self.LCD_CMD) # 001100 Display On,Cursor Off, Blink Off
self.lcd_byte(0x28, self.LCD_CMD) # 101000 Data length, number of lines, font size
self.lcd_byte(0x01, self.LCD_CMD) # 000001 Clear display
time.sleep(self.E_DELAY)
def lcd_byte(self, bits, mode):
# Send byte to data pins
# bits = data
# mode = True for character
# False for command
GPIO.output(self.LCD_RS, mode) # RS
# High bits
GPIO.output(self.LCD_D4, False)
GPIO.output(self.LCD_D5, False)
GPIO.output(self.LCD_D6, False)
GPIO.output(self.LCD_D7, False)
if bits & 0x10 == 0x10:
GPIO.output(self.LCD_D4, True)
if bits & 0x20 == 0x20:
GPIO.output(self.LCD_D5, True)
if bits & 0x40 == 0x40:
GPIO.output(self.LCD_D6, True)
if bits & 0x80 == 0x80:
GPIO.output(self.LCD_D7, True)
# Toggle 'Enable' pin
self.lcd_toggle_enable()
# Low bits
GPIO.output(self.LCD_D4, False)
GPIO.output(self.LCD_D5, False)
GPIO.output(self.LCD_D6, False)
GPIO.output(self.LCD_D7, False)
if bits & 0x01 == 0x01:
GPIO.output(self.LCD_D4, True)
if bits & 0x02 == 0x02:
GPIO.output(self.LCD_D5, True)
if bits & 0x04 == 0x04:
GPIO.output(self.LCD_D6, True)
if bits & 0x08 == 0x08:
GPIO.output(self.LCD_D7, True)
# Toggle 'Enable' pin
self.lcd_toggle_enable()
def lcd_toggle_enable(self):
# Toggle enable
time.sleep(self.E_DELAY)
GPIO.output(self.LCD_E, True)
time.sleep(self.E_PULSE)
GPIO.output(self.LCD_E, False)
time.sleep(self.E_DELAY)
def lcd_string(self, message, line):
# Send string to display
message = message.ljust(self.LCD_WIDTH, " ")
self.lcd_byte(line, self.LCD_CMD)
for i in range(self.LCD_WIDTH):
self.lcd_byte(ord(message[i]), self.LCD_CHR)
if __name__ == '__main__':
a = LCD1602()
while True:
a.lcd_string(''.join(sample(string.ascii_letters, k=8)), a.LCD_LINE_1)
a.lcd_string(''.join(sample(string.ascii_letters, k=8)), a.LCD_LINE_2)
time.sleep(3)
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