from machine import Pin
import time
import urandom

led =Pin(1, Pin.OUT)
button =Pin(28, Pin.IN,Pin.PULL_DOWN)

while True:
    print("Get ready...")
    led.value(0)
    time.sleep(urandom.uniform(2, 5))
    
    print("GO!")
    led.value(1)
    start_time = time.ticks_ms()
    
    while button.value() == 0:
        pass
    
    reaction_time = time.ticks_diff(time.ticks_ms(), start_time)
    led.value(0)
    print(f"Reaction time: {reaction_time} ms")
    time.sleep(2)