/**
 * Lab 4
 *
 * PWM Pin is configured to output a 20 Hz signal with a 50% duty cycle
 * on GPIO 2.
 *
 * ADC is configured to read the value of the PWM from GPIO 2 on GPIO 26.
 *
 * An interrupt is setup to read the ADC value every 25 ms and print it.
 */

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

#define PWM_PIN 2

#define ADC_PIN 26
#define ADC_FREQ 25

/**
 * Callback function for repeating timer to read ADC value
 * @param t The timer that triggered the callback
 * @return  True to keep the timer running, false to stop it
 */
bool repeating_timer_callback (struct repeating_timer *t) {
    // Read ADC value
    uint16_t result = adc_read();
    printf("ADC value: %d\n", result);

    return true;
}

/**
 * Setup Function for PWM and ADC
 * @param timer   Repeating timer for ADC
 */
void setup (struct repeating_timer *timer) {
    // PWM setup
    gpio_set_function(PWM_PIN, GPIO_FUNC_PWM);
    uint slice_num = pwm_gpio_to_slice_num(PWM_PIN);
    uint channel = pwm_gpio_to_channel(PWM_PIN);

    pwm_set_clkdiv(slice_num, 100); // 125 MHz / 100 = 1.25 MHz
    pwm_set_wrap(slice_num, 62500); // 1.25 MHz / 62500 = 20 Hz
    pwm_set_chan_level(slice_num, channel, 62500/2); // 50% duty cycle

    pwm_set_enabled(slice_num, true);

    // ADC setup
    adc_init();
    adc_gpio_init(ADC_PIN);
    adc_select_input(0);

    // Setup timer interrupt
    add_repeating_timer_ms(ADC_FREQ,
                           repeating_timer_callback,
                           NULL,
                           timer
    );
}

int main () {
    stdio_init_all();
    struct repeating_timer timer;
    setup(&timer);

    while (true)
    {
        tight_loop_contents();
    }
}