from machine import Pin,ADC,PWM

adc = ADC(Pin(32))
adc.width(ADC.WIDTH_9BIT)
adc.atten(ADC.ATTN_11DB)
pwm= PWM(Pin(2),freq=50)

while(1):
    val=adc.read()
    if val <=170:
        pwm.duty(102)
    elif val<=512:
        pwm.duty(512)
    else:
        pwm.duty(972)