Frage zu Python

**pinsel120866** · 13.01.2013, 15:25

Hallo,

ich habe ein 16x1 Zeichen LCD an mein RPi angehängt und mit folgendem Code von der Adafruit HP funktioniert es auch:

Code:

#!/usr/bin/python

from Adafruit_CharLCD import Adafruit_CharLCD
from subprocess import * 
from time import sleep, strftime
from datetime import datetime

lcd = Adafruit_CharLCD()

cmd = "ip addr show wlan0 | grep inet | awk '{print $2}' | cut -d/ -f1"

lcd.begin(16,1)

def run_cmd(cmd):
        p = Popen(cmd, shell=True, stdout=PIPE)
        output = p.communicate()[0]
        return output

while 1:
    lcd.clear()
    ipaddr = run_cmd(cmd)
        lcd.message(datetime.now().strftime('%b %d\n'))
        lcd.message(datetime.now().strftime('%H:%M:%S\n'))
#    lcd.message(datetime.now().strftime('%b %d  %H:%M:%S\n'))
#    lcd.message('IP %s' % ( ipaddr ) )
    sleep(1)

Nun will ich die Messwerte des Ultraschallmodules auf dem LCD ausgeben und folgenden Code in den obigen integrieren:

Code:

import time
import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)

GPIO_TRIGGER = 14
GPIO_ECHO = 15

adjustment = 7

print "Ultraschallmessung mit SRF04"

while True:

    GPIO.setup(GPIO_TRIGGER,GPIO.OUT)
    GPIO.setup(GPIO_ECHO,GPIO.IN)

    GPIO.output(GPIO_TRIGGER, False)

    time.sleep(0.5)

    GPIO.output(GPIO_TRIGGER, True)
    time.sleep(0.00001)
    start = time.time()
    GPIO.output(GPIO_TRIGGER, False)

    while GPIO.input(GPIO_ECHO)==0:
      pass

    start = time.time()

    while GPIO.input(GPIO_ECHO)==1:
      pass

    stop = time.time()

    elapsed = stop-start
    
    distance = elapsed * 17000 + 8
    distance = distance - adjustment

    print "Abstand: %.1f cm" % distance
    time.sleep(1)

    GPIO.cleanup()

Nur ist das nicht so einfach, zumindest bringe ich es nicht hin - könnte mir bitte hierbei jemand helfen, oder geht das gar nicht?

**Kampi** · 13.01.2013, 16:31

Hey,

du kannst zwei Programme miteinander verknüpfen.
Unter C geht das z.B. mit dem Befehl "system()". Dadurch kannst du in deinem C-Programm quasi einen Kommandozeilenbefehl ausführen.
Jetzt weiß ich nicht wie du was auf dem LCD anzeigen kannst, aber wenn das mittels Konsoleneingabe funktioniert kannst du es in dein Pythonprogramm mittels System machen:

http://www.python-kurs.eu/os_modul_shell.php

**pinsel120866** · 13.01.2013, 18:28

hi kampi,

als programmierpflaume habe ich so meine probleme. kannst du mir bei meinem beispiel helfen? ich will zuerst die messung durchführen und dann am lcd ausgeben.

**Kampi** · 13.01.2013, 18:53

Hey,

wie funktioniert den das mit der LCD-Ausgabe?
Ich hab damit noch nicht gearbeitet.
Wie kriegst du Daten oder Texte auf dem LCD angezeigt?

**pinsel120866** · 14.01.2013, 06:29

Das ist ein guter Hinweis, die LCD-Ausgabe ist eine "normale" Python-Datei. Ich werde mir das in den nächsten Tagen ansehen und mich dann nochmals melden.

Danke vorerst.

**pinsel120866** · 19.01.2013, 14:25

Ich habe es nun gelöst, die Werte werden am LCD ausgegeben:

Code:

#!/usr/bin/python

#
# based on code from lrvick and LiquidCrystal
# lrvic - https://github.com/lrvick/raspi-hd44780/blob/master/hd44780.py
# LiquidCrystal - https://github.com/arduino/Arduino/blob/master/libraries/LiquidCrystal/LiquidCrystal.cpp
#

from time import sleep

class Adafruit_CharLCD:

    # commands
    LCD_CLEARDISPLAY         = 0x01
    LCD_RETURNHOME         = 0x02
    LCD_ENTRYMODESET         = 0x04
    LCD_DISPLAYCONTROL         = 0x08
    LCD_CURSORSHIFT         = 0x10
    LCD_FUNCTIONSET         = 0x20
    LCD_SETCGRAMADDR         = 0x40
    LCD_SETDDRAMADDR         = 0x80

    # flags for display entry mode
    LCD_ENTRYRIGHT         = 0x00
    LCD_ENTRYLEFT         = 0x02
    LCD_ENTRYSHIFTINCREMENT     = 0x01
    LCD_ENTRYSHIFTDECREMENT     = 0x00

    # flags for display on/off control
    LCD_DISPLAYON         = 0x04
    LCD_DISPLAYOFF         = 0x00
    LCD_CURSORON         = 0x02
    LCD_CURSOROFF         = 0x00
    LCD_BLINKON         = 0x01
    LCD_BLINKOFF         = 0x00

    # flags for display/cursor shift
    LCD_DISPLAYMOVE         = 0x08
    LCD_CURSORMOVE         = 0x00

    # flags for display/cursor shift
    LCD_DISPLAYMOVE         = 0x08
    LCD_CURSORMOVE         = 0x00
    LCD_MOVERIGHT         = 0x04
    LCD_MOVELEFT         = 0x00

    # flags for function set
    LCD_8BITMODE         = 0x10
    LCD_4BITMODE         = 0x00
    LCD_2LINE             = 0x08
    LCD_1LINE             = 0x00
    LCD_5x10DOTS         = 0x04
    LCD_5x8DOTS         = 0x00

    def __init__(self, pin_rs=25, pin_e=24, pins_db=[23, 17, 21, 22], GPIO = None):
    # Emulate the old behavior of using RPi.GPIO if we haven't been given
    # an explicit GPIO interface to use
    if not GPIO:
        import RPi.GPIO as GPIO
       self.GPIO = GPIO
        self.pin_rs = pin_rs
        self.pin_e = pin_e
        self.pins_db = pins_db

        self.GPIO.setmode(GPIO.BCM)
        self.GPIO.setup(self.pin_e, GPIO.OUT)
        self.GPIO.setup(self.pin_rs, GPIO.OUT)

        for pin in self.pins_db:
            self.GPIO.setup(pin, GPIO.OUT)

    self.write4bits(0x33) # initialization
    self.write4bits(0x32) # initialization
    self.write4bits(0x28) # 2 line 5x7 matrix
    self.write4bits(0x0C) # turn cursor off 0x0E to enable cursor
    self.write4bits(0x06) # shift cursor right

    self.displaycontrol = self.LCD_DISPLAYON | self.LCD_CURSOROFF | self.LCD_BLINKOFF

    self.displayfunction = self.LCD_4BITMODE | self.LCD_1LINE | self.LCD_5x8DOTS
    self.displayfunction |= self.LCD_2LINE

    """ Initialize to default text direction (for romance languages) """
    self.displaymode =  self.LCD_ENTRYLEFT | self.LCD_ENTRYSHIFTDECREMENT
    self.write4bits(self.LCD_ENTRYMODESET | self.displaymode) #  set the entry mode

        self.clear()


    def begin(self, cols, lines):

    if (lines > 1):
        self.numlines = lines
            self.displayfunction |= self.LCD_2LINE
        self.currline = 0


    def home(self):

    self.write4bits(self.LCD_RETURNHOME) # set cursor position to zero
    self.delayMicroseconds(3000) # this command takes a long time!
    

    def clear(self):

    self.write4bits(self.LCD_CLEARDISPLAY) # command to clear display
    self.delayMicroseconds(3000)    # 3000 microsecond sleep, clearing the display takes a long time


    def setCursor(self, col, row):

    self.row_offsets = [ 0x00, 0x40, 0x14, 0x54 ]

    if ( row > self.numlines ): 
        row = self.numlines - 1 # we count rows starting w/0

    self.write4bits(self.LCD_SETDDRAMADDR | (col + self.row_offsets[row]))


    def noDisplay(self): 
    """ Turn the display off (quickly) """

    self.displaycontrol &= ~self.LCD_DISPLAYON
    self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)


    def display(self):
    """ Turn the display on (quickly) """

    self.displaycontrol |= self.LCD_DISPLAYON
    self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)


    def noCursor(self):
    """ Turns the underline cursor on/off """

    self.displaycontrol &= ~self.LCD_CURSORON
    self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)


    def cursor(self):
    """ Cursor On """

    self.displaycontrol |= self.LCD_CURSORON
    self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)


    def noBlink(self):
    """ Turn on and off the blinking cursor """

    self.displaycontrol &= ~self.LCD_BLINKON
    self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)


    def noBlink(self):
    """ Turn on and off the blinking cursor """

    self.displaycontrol &= ~self.LCD_BLINKON
    self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)


    def DisplayLeft(self):
    """ These commands scroll the display without changing the RAM """

    self.write4bits(self.LCD_CURSORSHIFT | self.LCD_DISPLAYMOVE | self.LCD_MOVELEFT)


    def scrollDisplayRight(self):
    """ These commands scroll the display without changing the RAM """

    self.write4bits(self.LCD_CURSORSHIFT | self.LCD_DISPLAYMOVE | self.LCD_MOVERIGHT);


    def leftToRight(self):
    """ This is for text that flows Left to Right """

    self.displaymode |= self.LCD_ENTRYLEFT
    self.write4bits(self.LCD_ENTRYMODESET | self.displaymode);


    def rightToLeft(self):
    """ This is for text that flows Right to Left """
    self.displaymode &= ~self.LCD_ENTRYLEFT
    self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)


    def autoscroll(self):
    """ This will 'right justify' text from the cursor """

    self.displaymode |= self.LCD_ENTRYSHIFTINCREMENT
    self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)


    def noAutoscroll(self): 
    """ This will 'left justify' text from the cursor """

    self.displaymode &= ~self.LCD_ENTRYSHIFTINCREMENT
    self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)


    def write4bits(self, bits, char_mode=False):
        """ Send command to LCD """

    self.delayMicroseconds(1000) # 1000 microsecond sleep

        bits=bin(bits)[2:].zfill(8)

        self.GPIO.output(self.pin_rs, char_mode)

        for pin in self.pins_db:
            self.GPIO.output(pin, False)

        for i in range(4):
            if bits[i] == "1":
                self.GPIO.output(self.pins_db[::-1][i], True)

    self.pulseEnable()

        for pin in self.pins_db:
            self.GPIO.output(pin, False)

        for i in range(4,8):
            if bits[i] == "1":
                self.GPIO.output(self.pins_db[::-1][i-4], True)

    self.pulseEnable()


    def delayMicroseconds(self, microseconds):
    seconds = microseconds / float(1000000)    # divide microseconds by 1 million for seconds
    sleep(seconds)


    def pulseEnable(self):
    self.GPIO.output(self.pin_e, False)
    self.delayMicroseconds(1)        # 1 microsecond pause - enable pulse must be > 450ns 
    self.GPIO.output(self.pin_e, True)
    self.delayMicroseconds(1)        # 1 microsecond pause - enable pulse must be > 450ns 
    self.GPIO.output(self.pin_e, False)
    self.delayMicroseconds(1)        # commands need > 37us to settle


    def message(self, text):
        """ Send string to LCD. Newline wraps to second line"""

        for char in text:
            if char == '\n':
                self.write4bits(0xC0) # next line
            else:
                self.write4bits(ord(char),True)


if __name__ == '__main__':

    lcd = Adafruit_CharLCD()

GPIO_TRIGGER = 14
GPIO_ECHO = 15

adjustment = 7

print "Ultraschallmessung mit SRF04"

while True:

    GPIO.setup(GPIO_TRIGGER,GPIO.OUT)
    GPIO.setup(GPIO_ECHO,GPIO.IN)

    GPIO.output(GPIO_TRIGGER, False)

    time.sleep(0.5)

    GPIO.output(GPIO_TRIGGER, True)
    time.sleep(0.00001)
    start = time.time()
    GPIO.output(GPIO_TRIGGER, False)

    while GPIO.input(GPIO_ECHO)==0:
      pass

    start = time.time()

    while GPIO.input(GPIO_ECHO)==1:
      pass

    stop = time.time()

    elapsed = stop-start
    
    distance = elapsed * 17000 + 8
    distance = distance - adjustment

    print "Abstand: %.1f cm" % distance
    time.sleep(1)

    GPIO.cleanup()



    lcd.clear()
#    lcd.message("  Adafruit 16x2\n  Standard LCD")
    lcd.message("Pinsel's\n RPi Bot")