etec224-button-led.py

#!/usr/bin/python3

import RPi.GPIO as GPIO
import time

LED_G = 16
LED_Y = 20
LED_R = 21
PBT1 = 17

GPIO.setmode(GPIO.BCM)

GPIO.setup(LED_G, GPIO.OUT)
GPIO.setup(LED_Y, GPIO.OUT)
GPIO.setup(LED_R, GPIO.OUT)
GPIO.setup(PBT1, GPIO.IN, pull_up_down=GPIO.PUD_UP)

state = 0 # variable to store LED State

try:

    while True:
        # wait here till pushbutton is pressed
        while( not GPIO.input(PBT1) ):
            time.sleep(0.1)
        while( GPIO.input(PBT1) ):
            time.sleep(0.1)

        GPIO.output(LED_G, 0)
        GPIO.output(LED_R, 0)
        GPIO.output(LED_Y, 0)

        if(state == 0):
            GPIO.output(LED_G, 1)
        elif(state == 1):
            GPIO.output(LED_Y, 1)
        else:
            GPIO.output(LED_R, 1)

        state = state + 1
        if(state >=3):
            state = 0


except KeyboardInterrupt:
    print("Ctrl+C Detected")
    GPIO.cleanup()