RPI.GPIO Help

MRAB python at mrabarnett.plus.com
Thu Aug 20 17:45:53 CEST 2015


On 2015-08-20 16:12, John McKenzie wrote:
>
>   Thanks for the reply. Also, thanks to Laura who replied via email.
>
>   Tried a bunch of things based off these comments and I always ended up
> with one of two situations, the channel conflict error, or an instant run
> and quit issue. This new version of the code runs but is unresponsive. I
> removed loops then put in a short sleep loop. while True:
>      time.sleep(0.1) It could be my hardware is done up wrong, but it
> looks OK. Perhaps it is always sleeping.
>
>   Anyone at all know about GPIO and the Pi under the Python library
> RPi.GPIO please feel free to advise as to what the problem is most likely
> to be.
>
>
> import atexit
> import time
> from blinkstick import blinkstick
> import RPi.GPIO as GPIO
>
> led = blinkstick.find_first()
> colour = 0
> timered = 0
> timeyellow = 0
> timeblue = 0
> timestamp = time.strftime("%H:%M:%S")
>
>
>
> GPIO.setmode(GPIO.BCM)
> GPIO.setup(22, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
> GPIO.setup(23, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
> GPIO.setup(24, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
>
>
>
> def red_button(channel):
>      colour = 1
>      while colour == 1:
>          print "Red Button pressed"
>          timered += 1
>
>
> def yellow_button(channel):
>      colour = 2
>      while colour == 2:
>          print "Yellow Button pressed"
>          timeyellow += 1
>
>
> def blue_button(channel):
>      colour = 3
>      while colour == 3:
>          print "Blue Button pressed"
>          timeblue += 1
>
> GPIO.add_event_detect(23, GPIO.RISING, callback=yellow_button,
> bouncetime=200)
> GPIO.add_event_detect(22, GPIO.RISING, callback=red_button,
> bouncetime=200)
> GPIO.add_event_detect(24, GPIO.RISING, callback=blue_button,
> bouncetime=200)
>
> while True:
>      time.sleep(0.1)
>
> def exit_handler():
>      print '\033[0;41;37mRed Team:\033[0m ', timered
>      print '\033[0;103;30mYellow Team:\033[0m ', timeyellow
>      print '\033[0;44;37mBlue Team:\033[0m ', timeblue
>      flog = open('flag1log.text', 'a')
>      flog.write(timestamp + '\n' + 'Red Team: ' + str(timered) + '\n' +
> 'Yellow Team: ' + str(timeyellow) + '\n' + 'Blue Team: ' + str(timeblue)
> + '\n')
>      flog.close()
> atexit.register(exit_handler)
> GPIO.cleanup()
>
>
The function 'red_button' will be called when a rising edge is detected.

In that function, you're assigning to 'colour' but not changing it in
the loop, so it's basically just a busy loop. However, you're trying to
change 'timered', which is a global variable, but you're not declaring
it as global, so that will raise UnboundLocalError.

Similar remarks apply to the other two callbacks.

I think you'd be better off detecting both the rising and falling
edges, with a callback for each, recording when each edge occurred
(duration of press = time of falling edge - time of rising edge).



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