from machine import Pin, ADC, Timer

L1 = Pin(23, Pin.OUT)
L2 = Pin(22, Pin.OUT)
L3 = Pin(21, Pin.OUT)
adc = ADC(Pin(32))


def tim(x):
    valor = adc.read()
    print(valor)  
    if valor <= 170:     
        L1.on()
        L2.off()
        L3.off()
    elif valor <= 341:   
        L1.off()
        L2.on()
        L3.off()
    else:                
        L1.off()
        L2.off()
        L3.on()

t0 = Timer(0)
t0.init(period=500, mode=Timer.PERIODIC, callback=tim)
adc.width(ADC.WIDTH_9BIT)
adc.atten(ADC.ATTN_11DB)

while(1):
    pass