from machine import Pin, PWM, ADC
frequency = 5000
led=PWM(Pin(2),frequency)
ldr=ADC(Pin(34))
ldr.width(ADC.WIDTH_10BIT) #11bit:2047 12bit:4095(default)  only 4bit 9,10,11,12
ldr.atten(ADC.ATTN_11DB)
m=Pin(4,Pin.IN)

while True:
    ldr_value = ldr.read()
    if(m.value()):
        led.duty(ldr_value);
    else:
        led.duty(0);