root@SpielzeugPI:~# cat lcd.sh
#!/bin/bash
cd /root

o1=""
o2=""

while(true)
do
 echo $(echo scale=1\;$(cat /run/t1)/1000|bc) > /run/line1

 l1=$(cat /run/line1)
 l2=$(cat /run/line2)

 r=0
 if test "$l1" != "$o1"
 then
  r=1
 fi
 if test "$l2" != "$o2"
 then
  r=1
 fi
 if test "$r" == "1"
 then
  ./hd44780_test.py "$l1" "$l2"
  o1="$l1"
  o2="$l2"
 fi

 sleep 1

done

root@SpielzeugPI:~# cat hd44780_test.py
#!/usr/bin/python
import time,sys
import RPi.GPIO as GPIO

# Zuordnung der GPIO Pins (ggf. anpassen)
LCD_RS = 4
LCD_E  = 17
LCD_DATA4 = 18
LCD_DATA5 = 22
LCD_DATA6 = 23
LCD_DATA7 = 24

LCD_WIDTH = 24          # Zeichen je Zeile
LCD_LINE_1 = 0x80       # Adresse der ersten Display Zeile
LCD_LINE_2 = 0xC0       # Adresse der zweiten Display Zeile
LCD_CHR = GPIO.HIGH
LCD_CMD = GPIO.LOW
E_PULSE = 0.0005
E_DELAY = 0.0005

def lcd_send_byte(bits, mode):
        # Pins auf LOW setzen
        GPIO.output(LCD_RS, mode)
        GPIO.output(LCD_DATA4, GPIO.LOW)
        GPIO.output(LCD_DATA5, GPIO.LOW)
        GPIO.output(LCD_DATA6, GPIO.LOW)
        GPIO.output(LCD_DATA7, GPIO.LOW)
        if bits & 0x10 == 0x10:
          GPIO.output(LCD_DATA4, GPIO.HIGH)
        if bits & 0x20 == 0x20:
          GPIO.output(LCD_DATA5, GPIO.HIGH)
        if bits & 0x40 == 0x40:
          GPIO.output(LCD_DATA6, GPIO.HIGH)
        if bits & 0x80 == 0x80:
          GPIO.output(LCD_DATA7, GPIO.HIGH)
        time.sleep(E_DELAY)
        GPIO.output(LCD_E, GPIO.HIGH)
        time.sleep(E_PULSE)
        GPIO.output(LCD_E, GPIO.LOW)
        time.sleep(E_DELAY)
        GPIO.output(LCD_DATA4, GPIO.LOW)
        GPIO.output(LCD_DATA5, GPIO.LOW)
        GPIO.output(LCD_DATA6, GPIO.LOW)
        GPIO.output(LCD_DATA7, GPIO.LOW)
        if bits&0x01==0x01:
          GPIO.output(LCD_DATA4, GPIO.HIGH)
        if bits&0x02==0x02:
          GPIO.output(LCD_DATA5, GPIO.HIGH)
        if bits&0x04==0x04:
          GPIO.output(LCD_DATA6, GPIO.HIGH)
        if bits&0x08==0x08:
          GPIO.output(LCD_DATA7, GPIO.HIGH)
        time.sleep(E_DELAY)
        GPIO.output(LCD_E, GPIO.HIGH)
        time.sleep(E_PULSE)
        GPIO.output(LCD_E, GPIO.LOW)
        time.sleep(E_DELAY)

def display_init():
        lcd_send_byte(0x33, LCD_CMD)
        lcd_send_byte(0x32, LCD_CMD)
        lcd_send_byte(0x28, LCD_CMD)
        lcd_send_byte(0x0C, LCD_CMD)
        lcd_send_byte(0x06, LCD_CMD)
        lcd_send_byte(0x01, LCD_CMD)

def lcd_message(message):
        message = message.ljust(LCD_WIDTH," ")
        for i in range(LCD_WIDTH):
          lcd_send_byte(ord(message[i]),LCD_CHR)

if __name__ == '__main__':

        # initialisieren
        GPIO.setmode(GPIO.BCM)
        GPIO.setwarnings(False)
        GPIO.setup(LCD_E, GPIO.OUT)
        GPIO.setup(LCD_RS, GPIO.OUT)
        GPIO.setup(LCD_DATA4, GPIO.OUT)
        GPIO.setup(LCD_DATA5, GPIO.OUT)
        GPIO.setup(LCD_DATA6, GPIO.OUT)
        GPIO.setup(LCD_DATA7, GPIO.OUT)

        display_init()

        lcd_send_byte(LCD_LINE_1, LCD_CMD)
        lcd_message(sys.argv[1])
        lcd_send_byte(LCD_LINE_2, LCD_CMD)
        lcd_message(sys.argv[2])

root@SpielzeugPI:~# cat steuern.sh
#!/bin/bash
while(true)
do
 t=$(t1)
 echo $t
 echo $t > /run/t1
 if test "$t" -lt 23000
 then
  relais 1 1
 else
  relais 1 0
 fi
done