from machine import Pin, ADC
from time import sleep

sensor = ADC(26)

RL = 10000
vcc = 5

R0 = 15000   # replace with calibrated value

while True:

    sensor_value = sensor.read_u16()
    voltage = sensor_value * (3.3 / 65535)

    print("Sensor Value:", sensor_value)
    print("Voltage:", voltage)

    Rs = RL * (vcc - voltage) / voltage

    ratio = Rs / R0

    ppm = 116.6020682 * (ratio ** -2.769034857)

    print("Gas Value:", ppm, "PPM")
    print("-----------------------")

    sleep(1)