import machine
import time 

# Define the GPIO pins for the traffic light LEDs 
RED_LED_PIN = 1   # GP0
YELLOW_LED_PIN = 5  # GP1
GREEN_LED_PIN = 9  # GP2

# Initialize the GPIO pins for the LEDs
red_led = machine.Pin(RED_LED_PIN, machine.Pin.OUT)
yellow_led = machine.Pin(YELLOW_LED_PIN, machine.Pin.OUT)
green_led = machine.Pin(GREEN_LED_PIN, machine.Pin.OUT)

# Function to turn on the specified LED and turn off the others
def turn_on_led(led_pin):
    red_led.value(led_pin == RED_LED_PIN)
    yellow_led.value(led_pin == YELLOW_LED_PIN)
    green_led.value(led_pin == GREEN_LED_PIN)

# Traffic light sequence 
while True:
    # Red light
    turn_on_led(RED_LED_PIN)
    time.sleep(5)  # RED light for 5 seconds

    # Red and yellow light (transition)
    turn_on_led(YELLOW_LED_PIN)
    time.sleep(2)  # RED and yellow light for 2 seconds

    # Green light
    turn_on_led(GREEN_LED_PIN)
    time.sleep(5)  # GREEN light for 5 seconds

    # Yellow light (transition)
    turn_on_led(YELLOW_LED_PIN)
    time.sleep(2)  # YELLOW light for 2 seconds