python socket issue with while true

Question

I'm running this script on a raspberry for a game I created, where I have three different inputs in my while true:.

One of them is getting a socket message from a different raspberry. But the problem is that the rest of my while true doesnt execute no more. Only the first IF statement after I received the socket message.

How to get them all running?

Thanks in advance

#!/usr/bin/python
import RPi.GPIO as GPIO 
import time
import socket
import pygame
import serial
GPIO.setmode(GPIO.BCM)
UDP_IP = "192.168.0.21"
UDP_PORT = 20
sock = socket.socket(socket.AF_INET, # Internet
 socket.SOCK_DGRAM) # UDP
sock.bind((UDP_IP, 20))
# Klopspelout, pianospel, sleutelspel, totaalspel
pinList = [27, 22, 4, 17]
klopinput = 21
sleutelinput = 11
# loop through pins
for i in pinList: 
 GPIO.setup(i, GPIO.OUT) 
GPIO.setup(klopinput, GPIO.IN)
GPIO.setup(sleutelinput, GPIO.IN, GPIO.PUD_UP)
# time to sleep between operations in the main loop
SleepTimeL = 2
#variables
totaal = 0
klop = 0 
sleutel = 0 
piano = 0
wacht = 0
GPIO.output(pinList[0], GPIO.LOW)
GPIO.output(pinList[1], GPIO.LOW)
GPIO.output(pinList[2], GPIO.LOW)
GPIO.output(pinList[3], GPIO.LOW)
data = 0
# main loop
#GPIO.cleanup()
while True:
 #if GPIO.input(klopinput) == True:
 # GPIO.output(pinList[0], GPIO.HIGH)
 # totaal += 1
 # print ('klopspel is goed')
 # time.sleep(SleepTimeL)
 # GPIO.output(pinList[0], GPIO.LOW)
 data, addr = sock.recvfrom(1024) # buffer size is 1024 bytes
 print "received message:", data
 if data == "slotpiano2":
 print "slot open"
 totaal += 1
 time.sleep(1)
 if GPIO.input(klopinput) == True and wacht == 0 and klop == 0:
 GPIO.output(pinList[1], GPIO.HIGH)
 totaal += 1
 klop = 1
 print ('klop is goed')
 time.sleep(SleepTimeL)
 GPIO.output(pinList[1], GPIO.LOW)
 time.sleep(SleepTimeL)
 if GPIO.input(sleutelinput) == False and sleutel == 0:
 GPIO.output(pinList[0], GPIO.HIGH)
 totaal += 1
 sleutel = 1
 wacht = 1
 print ('Sleutel is goed')
 time.sleep(SleepTimeL)
 GPIO.output(pinList[0], GPIO.LOW) 
 time.sleep(SleepTimeL)
 wacht = 0 
 if totaal == 3:
 GPIO.output(pinList[3], GPIO.HIGH) 
 totaal = 0
 sleutel = 0
 klop = 0
 print ('reset')
 time.sleep(SleepTimeL)
 GPIO.output(pinList[3], GPIO.LOW)

• AS Mackay: On each loop, sock.recvfrom() will block until data arrives on the socket - is this what you intended? Or did you want to ignore the socket if there is no data and move on to checking the GPIO inputs?
• W de wee: Or did you want to ignore the socket if there is no data and move on to checking the GPIO inputs? Yes, that last is correct.

Answer 1

OK as per your comment, if you want avoid blocking on the socket then you need to set it to nonblocking and use the select() function. I've posted a copy of your code below that shows the necessary edit, based on this answer, and there is lots of information about select() in the Python documentation.

#!/usr/bin/python
import RPi.GPIO as GPIO 
import time
import socket
import pygame
import serial
import select # select() function <---------
GPIO.setmode(GPIO.BCM)
UDP_IP = "192.168.0.21"
UDP_PORT = 20
sock = socket.socket(socket.AF_INET, # Internet
 socket.SOCK_DGRAM) # UDP
sock.bind((UDP_IP, 20))
sock.setblocking(0) # set to non-blocking <-----------
# Klopspelout, pianospel, sleutelspel, totaalspel
pinList = [27, 22, 4, 17]
klopinput = 21
sleutelinput = 11
# loop through pins
for i in pinList: 
 GPIO.setup(i, GPIO.OUT) 
GPIO.setup(klopinput, GPIO.IN)
GPIO.setup(sleutelinput, GPIO.IN, GPIO.PUD_UP)
# time to sleep between operations in the main loop
SleepTimeL = 2
#variables
totaal = 0
klop = 0 
sleutel = 0 
piano = 0
wacht = 0
GPIO.output(pinList[0], GPIO.LOW)
GPIO.output(pinList[1], GPIO.LOW)
GPIO.output(pinList[2], GPIO.LOW)
GPIO.output(pinList[3], GPIO.LOW)
data = 0
# main loop
#GPIO.cleanup()
while True:
 #if GPIO.input(klopinput) == True:
 # GPIO.output(pinList[0], GPIO.HIGH)
 # totaal += 1
 # print ('klopspel is goed')
 # time.sleep(SleepTimeL)
 # GPIO.output(pinList[0], GPIO.LOW)
 fds = select.select([sock], [], [], 1.0) <-----------
 if (fds[0]): # sock has some data
 data, addr = sock.recvfrom(1024) # buffer size is 1024 bytes
 print "received message:", data
 if data == "slotpiano2":
 print "slot open"
 totaal += 1
 time.sleep(1)
 if GPIO.input(klopinput) == True and wacht == 0 and klop == 0:
 GPIO.output(pinList[1], GPIO.HIGH)
 totaal += 1
 klop = 1
 print ('klop is goed')
 time.sleep(SleepTimeL)
 GPIO.output(pinList[1], GPIO.LOW)
 time.sleep(SleepTimeL)
 if GPIO.input(sleutelinput) == False and sleutel == 0:
 GPIO.output(pinList[0], GPIO.HIGH)
 totaal += 1
 sleutel = 1
 wacht = 1
 print ('Sleutel is goed')
 time.sleep(SleepTimeL)
 GPIO.output(pinList[0], GPIO.LOW) 
 time.sleep(SleepTimeL)
 wacht = 0 
 if totaal == 3:
 GPIO.output(pinList[3], GPIO.HIGH) 
 totaal = 0
 sleutel = 0
 klop = 0
 print ('reset')
 time.sleep(SleepTimeL)
 GPIO.output(pinList[3], GPIO.LOW)

(NB set the timeout to something relevant to your application if 1.0 seconds is not acceptable.)