#include <stdio.h>             // Standard library for input and output, used for printf.
#include "pico/stdlib.h"       // Standard library for basic Pico functions, such as GPIO and timing.
#include "hardware/adc.h"      // Library for controlling the ADC (Analog-to-Digital Converter).

// Definitions
#define ADC_TEMPERATURE_CHANNEL 4   // ADC channel corresponding to the internal temperature sensor

// Function to convert the ADC reading to temperature in degrees Celsius
float adc_to_temperature(uint16_t adc_value) {
  // Constants provided in the RP2040 datasheet
  const float conversion_factor = 3.3f / (1 << 12);  // Conversion from 12-bit (0-4095) to 0-3.3V
  float voltage = adc_value * conversion_factor;     // Converts the ADC value to voltage
  float celsius_temperature = 27.0f - (voltage - 0.706f) / 0.001721f;  // Equation provided for conversion

  return celsius_temperature;
}

// Function to convert Celsius to Fahrenheit
float celsius_to_fahrenheit(float celsius) {
  return ((celsius * 1.8f) + 32); // Physics equation for Celsius to Fahrenheit conversion
}

int main() {
  // Initializes serial communication to allow printf usage
  stdio_init_all();

  // Initializes the ADC module of the Raspberry Pi Pico
  adc_init();

  // Selects ADC channel 4 (internal temperature sensor)
  adc_set_temp_sensor_enabled(true);  // Enables the internal temperature sensor
  adc_select_input(ADC_TEMPERATURE_CHANNEL);  // Selects the temperature sensor channel

  // Infinite loop for continuous temperature readings
  while (true) {
    // Reads the ADC value from the selected channel (temperature sensor)
    uint16_t adc_value = adc_read();

    // Converts the ADC value to temperature in degrees Celsius
    float celsius_temperature = adc_to_temperature(adc_value);

    // Converts Celsius to Fahrenheit
    float fahrenheit_temperature = celsius_to_fahrenheit(celsius_temperature);

    // Prints the temperature on the serial communication
    printf("Temperature: %.2f °F\n", fahrenheit_temperature);

    // Delay of 1000 milliseconds (1 second) between readings
    sleep_ms(1000);
  }

  return 0;
}