import time
from machine import Timer, Pin


def start_blink(pin, delay_ms):

    def callback(timer):
        pin(not pin())

    timer = Timer(-1)
    # RP2040 does not support hardware timers
    # -1 stands for software timer

    timer.init(period=delay_ms, mode=Timer.PERIODIC, callback=callback)
    return timer


def stop_blink(pin, timer):
    timer.deinit()
    while pin():
        pin.off()
        time.sleep_us(100)



led = Pin(4, Pin.OUT)
# LED: RP Pico
# led = Pin(25, Pin.OUT)

led_timer = start_blink(led, 100)
time.sleep(2)
stop_blink(led, led_timer)