main.cpp

#include <stdio.h>
#include "pico/stdlib.h"
#include "hardware/adc.h"

// The built in LED
#define LED_PIN 25
#define TEMP_ADC 4

const float conversion_factor = 3.3f / (1 << 12);

/*
    A simple application to blink the LED light, and print out the temperature.
*/
int main() {
    stdio_init_all();

    gpio_init(LED_PIN);
    gpio_set_dir(LED_PIN, GPIO_OUT);

    adc_init();
    adc_gpio_init(26);
    adc_set_temp_sensor_enabled(true);

    adc_select_input(TEMP_ADC);

    while (true) {
        gpio_put(LED_PIN, true);
        sleep_ms(1000);

        gpio_put(LED_PIN, false);
        sleep_ms(1000);

        const float voltage = adc_read() * conversion_factor;
        const float temperature = 27 - (voltage - 0.706) / 0.001721;

        printf("Hello, world! The temperature is: %fc\n", temperature);
    }
}