I am trying to read AI using mraa library python3,below is the code.But I am getting a Invalid AIO pin specified - do you have an ADC? error

import mraa

import time

led_gpio = mraa.Gpio(61)

led_gpio.dir(mraa.DIR_OUT)

#PD26_AIN_SEN1 pin 20

pot_aio = mraa.Aio(20)

def rugged_board_write_led(value):

value = 1 if value==0 else 0

led_gpio.write(value)

def rugged_board_read_pot():

potvalue = pot_aio.readFloat()

return potvalue

value = 1

while True:

value = 1 if value==0 else 0

#toggle led

print(rugged_board_write_led(value))

time.sleep(1)

print(rugged_board_read_pot())

time.sleep(1)