import machine
import math
import time

#######################################
# Pin and constant definitions
#######################################
ANALOGUE_INPUT_PIN = 26
DECIMAL_PRECISION = 3
ADC_RANGE = float((math.pow(2, 16) - 1))

#######################################
# Global variables
#######################################
prev_analogue_voltage = -1

#######################################
# Function definitions
#######################################

# Function to read the ADC pin and
# to convert the digital value to a voltage level in the 0-3.3V range
def read_analogue_voltage(pin):
  global prev_analogue_voltage, DECIMAL_PRECISION

  # Take MEASUREMENT_COUNT measurements and average them
  total_value = 0
  MEASUREMENT_COUNT = 16
  for _ in range(MEASUREMENT_COUNT):
    total_value += pin.read_u16()
  average_value = total_value // MEASUREMENT_COUNT

  # Convert the average digital value to an analogue voltage value
  analogue_voltage = round((average_value / ADC_RANGE) * 3.3, DECIMAL_PRECISION)

  if analogue_voltage != prev_analogue_voltage:
    prev_analogue_voltage = analogue_voltage

    # Temperature Reading
    # When using the NTC, change the line below to
    # if True
    # then observe the temperature values on console.
    # Note that the implementation displays the absolute value.
    # So, both -24.0C and 24.0C appear as 24.0.
    DECIMAL_PRECISION = 2
    temp = 0
    # Use the formula from https://docs.wokwi.com/parts/wokwi-ntc-temperature-sensor
    temp = round(1 / (math.log(1 / (ADC_RANGE / average_value - 1)) / 3950 + 1.0 / 298.15) - 273.15, 1)
    print(f'temp: {temp} C')
    print(f'voltage: {analogue_voltage} mV')
    

# Function to setup GPIO/ADC pins
def setup():
  global analogue_voltage_pin

  analogue_voltage_pin = machine.ADC(ANALOGUE_INPUT_PIN)

if __name__ == '__main__':
  setup()
  while True:
    read_analogue_voltage(analogue_voltage_pin)
    time.sleep(0.5)