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import wiringpi2 as wiringpi

# Declare Constants
LED = 0
BTN = 1

INPUT = 0
OUTPUT = 1
PWM = 2

HIGH = 1
LOW = 0

PUD_DOWN = 1
PUD_UP = 2
PUD_RESET = 0

wiringpi.wiringPiSetup()

# Turn first pin 0 as output and switch it ON
wiringpi.pinMode(LED, OUTPUT)
wiringpi.digitalWrite(LED, HIGH)


# Turn first pin 1 as input
wiringpi.pinMode(BTN, INPUT)
wiringpi.pullUpDnControl(BTN, PUD_UP) #pull up to 3.3V,make btnPin a stable level

try:
	while True:
		if not wiringpi.digitalRead(BTN):     		# If button is pressed 
			wiringpi.digitalWrite(LED, HIGH) 	# switch on LED. 
		else:
			wiringpi.digitalWrite(LED, LOW)		# switch off LED. 
		wiringpi.delay(1)                      		# delay 0.05s
finally:                                 			# when you CTRL+C exit, we clean up
	wiringpi.digitalWrite(LED, LOW)         		# switch off LED. 
	wiringpi.pinMode(LED, INPUT)              		# sets ledPin to Input

# btnPin is already an input, so no need to change anything