import RPi.GPIO as GPIO
import time

LED_PIN = 17    # GPIO phisical pin

GPIO.setmode(GPIO.BCM)
GPIO.setup(LED_PIN, GPIO.OUT)

# Alternate every second, turning an LED on and off. Stopped by CTRL+C
try:
    while True:
        GPIO.output(LED_PIN, GPIO.HIGH)
        time.sleep(1)
        GPIO.output(LED_PIN, GPIO.LOW)
        time.sleep(1)
except KeyboardInterrupt:
    GPIO.cleanup()