LCD scherm 20×4 met behulp van I2C aansturen

lcd20x4.py

#!/usr/bin/python
#  https://raspberrytips.nl/lcd-scherm-20x4-i2c-raspberry-pi/

import sys
import smbus
import time
import datetime
import subprocess

I2C_ADDR  = 0x3F # I2C device address
LCD_WIDTH = 20   # Maximum characters per line

# Define some device constants
LCD_CHR = 1 # Mode - Sending data
LCD_CMD = 0 # Mode - Sending command

LCD_LINE_1 = 0x80 # LCD RAM address for the 1st line
LCD_LINE_2 = 0xC0 # LCD RAM address for the 2nd line
LCD_LINE_3 = 0x94 # LCD RAM address for the 3rd line
LCD_LINE_4 = 0xD4 # LCD RAM address for the 4th line


LCD_BACKLIGHT  = 0x08  # On 0X08 / Off 0x00

ENABLE = 0b00000100 # Enable bit

E_PULSE = 0.0005
E_DELAY = 0.0005

bus = smbus.SMBus(1) # Rev 2 Pi uses 1

def run_cmd(cmd):
    return subprocess.check_output(cmd, shell=True).decode('utf-8')

def get_my_ipwlan():
    val = run_cmd("/sbin/ifconfig wlan0 | grep 'inet addr:' | cut -d: -f2 | awk '{ print $1}'")[:-1]
    if val == "":
        val = "No connection!"
    return val

def get_my_ipeth():
    val = run_cmd("/sbin/ifconfig eth0 | grep 'inet addr:' | cut -d: -f2 | awk '{ print $1}'")[:-1]
    if val == "":
        val = "No connection"
    return val

def lcd_init():
  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):

  bits_high = mode | (bits & 0xF0) | LCD_BACKLIGHT
  bits_low = mode | ((bits<<4) & 0xF0) | LCD_BACKLIGHT

  bus.write_byte(I2C_ADDR, bits_high)
  lcd_toggle_enable(bits_high)

  bus.write_byte(I2C_ADDR, bits_low)
  lcd_toggle_enable(bits_low)

def lcd_toggle_enable(bits):
  time.sleep(E_DELAY)
  bus.write_byte(I2C_ADDR, (bits | ENABLE))
  time.sleep(E_PULSE)
  bus.write_byte(I2C_ADDR,(bits & ~ENABLE))
  time.sleep(E_DELAY)

def lcd_string(message,line):

  message = message.ljust(LCD_WIDTH," ")

  lcd_byte(line, LCD_CMD)

  for i in range(LCD_WIDTH):
    lcd_byte(ord(message[i]),LCD_CHR)

def main():

  lcd_init()

  while True:

    now = datetime.datetime.now()

    lcd_string("RASPBERRYTIPS.NL",LCD_LINE_1)
    lcd_string( str(now.day)+'/'+str(now.month)+'/'+str(now.year)+' '+str(now.hour)+':'+str(now.minute),LCD_LINE_2)
    lcd_string("W:{}".format(get_my_ipwlan()),LCD_LINE_3)
    lcd_string("E:{}".format(get_my_ipeth()),LCD_LINE_4)
    time.sleep(60)

if __name__ == '__main__':

  try:
    main()
  except KeyboardInterrupt:
    pass
  finally:
    lcd_byte(0x01, LCD_CMD)