C_Book_Examples/pwm_sample/pwm_sample.c

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

#define LED_PIN  PICO_DEFAULT_LED_PIN   // LED
#define PWM_SUB_PIN 2                   // サブ用

#define PWM_FREQ    1000
#define PWM_DIVIDER 100.0f

#define PI 3.14159265358979323846

uint slice_num = 0;
uint sub_slice = 0;
uint16_t wrap = 0;

void pwm_irq_handler(void)
{
    static uint counter = 0;

    pwm_clear_irq(slice_num);
    if(counter++ >= PWM_FREQ) {
        counter = 0;
    }
    double amp = fabs(sin(PI * ((double)counter/(double)PWM_FREQ)));
    uint16_t cc = (uint16_t)((double)wrap * amp);
    pwm_set_gpio_level(LED_PIN, cc);
    pwm_set_gpio_level(PWM_SUB_PIN, cc);
}

int main()
{
    stdio_init_all();

    gpio_set_function(LED_PIN,GPIO_FUNC_PWM );
    gpio_set_function(PWM_SUB_PIN,GPIO_FUNC_PWM );

    pwm_config c = pwm_get_default_config();
    pwm_config_set_clkdiv(&c, PWM_DIVIDER);
    wrap = (clock_get_hz(clk_sys) / PWM_DIVIDER) / PWM_FREQ;
    pwm_config_set_wrap(&c, wrap);

    // LEDのスライスを設定
    slice_num = pwm_gpio_to_slice_num(LED_PIN);
    pwm_init(slice_num, &c, false);
    // サブのスライスを設定
    sub_slice = pwm_gpio_to_slice_num(PWM_SUB_PIN);
    pwm_init(sub_slice, &c, false);

    // 念のためにIRQをクリアしておく
    pwm_clear_irq(slice_num);
    //
    pwm_set_irq_enabled(slice_num, true);
    irq_set_exclusive_handler(PWM_DEFAULT_IRQ_NUM(), pwm_irq_handler);
    irq_set_enabled(PWM_DEFAULT_IRQ_NUM(), true);

    pwm_set_gpio_level(LED_PIN, wrap/2);
    pwm_set_gpio_level(PWM_SUB_PIN, wrap/2);

    pwm_set_enabled(slice_num, true);
    pwm_set_enabled(sub_slice, true);

    while (true) {
        tight_loop_contents();
    }
}