import time
from machine import Pin

time.sleep(0.1) # Wait for USB to become ready

# Define period
period = 0.5
speed = 2*period

# Define GPIO pins
blue_led_pin = 21 
green_led_pin = 20
red_led_pin = 19

# Initialize LED
blue_led = Pin(blue_led_pin, Pin.OUT)
green_led = Pin(green_led_pin, Pin.OUT)
red_led = Pin(red_led_pin, Pin.OUT)

def sequence(period:int=1):
    blue_led.on()
    time.sleep(period)
    blue_led.off()
    green_led.on()
    time.sleep(period)
    green_led.off()
    red_led.on()
    time.sleep(period)
    red_led.off()

# MAIN PROGRAM
print(f"Sequence speed is {speed} s")

while True:
    sequence(period)