from machine import Timer, Pin
import time

led1 = Pin(11, Pin.OUT)
led2 = Pin(2, Pin.OUT)
led3 = Pin(42, Pin.OUT)
led4 = Pin(41, Pin.OUT)
ledlist = [led1, led2, led3, led4]
#熄灭所有LED灯
led1.value(0)
led2.value(0)
led3.value(0)
led4.value(0)
k = 0 #循环计数使用
#定时器中断服务程序
def f1(t):
    global k
    myindex = k % 4
    #每次中断按顺序翻转一个LED灯
    ledlist[myindex].value(1 - ledlist[myindex].value())
    print(k)
    k = k + 1
#初始化定时器1，周期为500ms
tim1 = Timer(1)
tim1.init(period=500, mode=Timer.PERIODIC, callback=f1)
#循环处理，每3秒修改一次频率
while True:
    pass
    time.sleep(3)
    tim1.init(period=300, mode=Timer.PERIODIC, callback=f1)
    time.sleep(3)
    tim1.init(period=100, mode=Timer.PERIODIC, callback=f1)