from machine import Pin, ADC

botao = Pin(19, Pin.IN, Pin.PULL_UP)
ldr = ADC(Pin(33), atten=ADC.ATTN_11DB)
rele = Pin(23, Pin.OUT)

limmax = 30000

while True:
    clara = ldr.read_u16()
    if clara > limmax:
        rele.on()
    elif clara < limmax*0.9:
        rele.off()
        
    if botao.value() == 0:
        limmax = clara
        #print (limmax)