RPi: read 3.2' TFT touchscreen buttons

#!/usr/bin/env python2
# Example script to read button input from Banggood's 3.2' TFT touchscreen
# Cancel script execution with Ctrl+C
import time
import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BOARD)
pins = {12: "K1", 16: "K2", 18: "K3"}
for n in pins:
    GPIO.setup(n, GPIO.IN, pull_up_down=GPIO.PUD_UP)
    # The buttons have a little bounce, 20ms seems to be a good threshold
    GPIO.add_event_detect(n, GPIO.BOTH, bouncetime=20)

try:
    while True:
        for n, name in pins.iteritems():
            if GPIO.event_detected(n):
                if not GPIO.input(n): # Pull-up: reversed
                    print "  Press %d / %s" % (n, name)
                else:
                    print "Release %d / %s" % (n, name)
        time.sleep(0.02) # Polling is a bad thing, let the CPU rest
except KeyboardInterrupt:
    pass

for n in pins:
    GPIO.remove_event_detect(n)