from machine import Pin
import time

led1 = Pin(15, Pin.OUT)
led2 = Pin(14, Pin.OUT)
led3 = Pin(13, Pin.OUT)

start_btn = Pin(16, Pin.IN, Pin.PULL_UP)
stop_btn  = Pin(17, Pin.IN, Pin.PULL_UP)

running = False

def turn_off_all():
    led1.off()
    led2.off()
    led3.off()

print("START = Click Green button \nSTOP = Press and hold Red button for a few secs")

while True:
    
    if start_btn.value() == 0:
        running = True

    
    if stop_btn.value() == 0:
        running = False
        turn_off_all()

    if running:
        led1.toggle()
        time.sleep(0.5)
        if not running: continue

        led2.toggle()
        time.sleep(0.5)
        if not running: continue

        led3.toggle()
        time.sleep(0.5)
    else:
        turn_off_all()