brickpico

/* pwm.c
   Copyright (C) 2023 Timo Kokkonen <tjko@iki.fi>

   SPDX-License-Identifier: GPL-3.0-or-later

   This file is part of BrickPico.

   BrickPico is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   BrickPico is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with BrickPico. If not, see <https://www.gnu.org/licenses/>.
*/

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

#include "brickpico.h"



/* Map of PWM signal output pins.
   Every two pins must be the A and B pins of same PWM slice.
 */
uint8_t output_gpio_pwm_map[OUTPUT_MAX_COUNT] = {
	PWM1_PIN,
	PWM2_PIN,
	PWM3_PIN,
	PWM4_PIN,
	PWM5_PIN,
	PWM6_PIN,
	PWM7_PIN,
	PWM8_PIN,
	PWM9_PIN,
	PWM10_PIN,
	PWM11_PIN,
	PWM12_PIN,
	PWM13_PIN,
	PWM14_PIN,
	PWM15_PIN,
	PWM16_PIN,
};


uint16_t pwm_out_top = 0;

/* Set PMW output signal duty cycle.
 */
void set_pwm_duty_cycle(uint out, float duty)
{
	uint level, pin;

	assert(out < OUTPUT_COUNT);
	pin = output_gpio_pwm_map[out];
	if (duty >= 100.0) {
		level = pwm_out_top + 1;
	} else if (duty > 0.0) {
		level = (duty * (pwm_out_top + 1) / 100);
	} else {
		level = 0;
	}
	pwm_set_gpio_level(pin, level);
}



/* Initialize PWM hardware to generate 25kHz PWM signal on output pins.
 */

#define PWM_TOP_MAX (1<<16)

void setup_pwm_outputs()
{
	uint32_t sys_clock = clock_get_hz(clk_sys);
	pwm_config config = pwm_get_default_config();
	uint pwm_freq = cfg->pwm_freq;
	uint clk_div = 1;
	uint slice_num, top;
	int i;


	if (pwm_freq < 10)
		pwm_freq = 10;
	else if (pwm_freq > 100000)
		pwm_freq = 100000;

	log_msg(LOG_NOTICE, "Initializing PWM outputs...");
	log_msg(LOG_NOTICE, "PWM Frequency: %u Hz", pwm_freq);

	top = sys_clock / clk_div / pwm_freq / 2 - 1;  /* for phase-correct PWM signal */
	if (top >= PWM_TOP_MAX) {
		clk_div = top / PWM_TOP_MAX + 1;
		log_msg(LOG_DEBUG, "adjust clock divider: %u", clk_div);
		top = sys_clock / clk_div / pwm_freq / 2 - 1;  /* for phase-correct PWM signal */
	}
	pwm_out_top = top;

	log_msg(LOG_DEBUG, "PWM: TOP=%u (max %u), CLK_DIV=%u", pwm_out_top, PWM_TOP_MAX, clk_div);
	pwm_config_set_clkdiv_int(&config, clk_div);
	pwm_config_set_phase_correct(&config, 1);
	pwm_config_set_wrap(&config, pwm_out_top);

	/* Configure PWM outputs */

	for (i = 0; i < OUTPUT_COUNT; i=i+2) {
		uint pin1 = output_gpio_pwm_map[i];
		uint pin2 = output_gpio_pwm_map[i + 1];

		gpio_set_function(pin1, GPIO_FUNC_PWM);
		gpio_set_function(pin2, GPIO_FUNC_PWM);
		slice_num = pwm_gpio_to_slice_num(pin1);
		/* two consecutive pins must belong to same PWM slice... */
		assert(slice_num == pwm_gpio_to_slice_num(pin2));
		pwm_init(slice_num, &config, true);
	}

}