led_pwm.c

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/*
 * This program 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.
 *
 * This program 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 this program; if not, see <http://www.gnu.org/licenses/>
 */

#include "pios.h"               /* PIOS_LED_* -- FIXME: include is too coarse */
#include "led_pwm.h"            /* API definition */

static uint32_t led_pwm_on_p(uint32_t pwm_period, uint32_t pwm_sweep_steps, uint32_t uptime, uint8_t *fraction) {
        /* 0 - pwm_sweep_steps */
        uint32_t curr_step = (uptime / pwm_period) % pwm_sweep_steps;

        /* fraction of pwm_period */
        uint32_t pwm_duty = pwm_period * curr_step / pwm_sweep_steps;

        /* ticks once per full sweep */
        uint32_t curr_sweep = (uptime / (pwm_period * pwm_sweep_steps));

        /* reverse direction in odd sweeps */
        if (curr_sweep & 1) {
                pwm_duty = pwm_period - pwm_duty;
        }

        if (fraction) {
                *fraction = 255 * pwm_duty / pwm_period;
        }

        return ((uptime % pwm_period) > pwm_duty) ? 1 : 0;
}

void led_pwm_config(struct led_pwm_state *leds,
                        uint32_t pwm_1_period_us,
                        uint32_t pwm_1_sweep_steps,
                        uint32_t pwm_2_period_us,
                        uint32_t pwm_2_sweep_steps)
{
        /* PWM #1 */
        if (pwm_1_period_us > 0) {
                leds->pwm_1_enabled     = true;
                leds->pwm_1_period_us   = pwm_1_period_us;
                leds->pwm_1_sweep_steps = pwm_1_sweep_steps;
        } else {
                leds->pwm_1_enabled     = false;
        }


        /* PWM #2 */
        if (pwm_2_period_us > 0) {
                leds->pwm_2_enabled     = true;
                leds->pwm_2_period_us   = pwm_2_period_us;
                leds->pwm_2_sweep_steps = pwm_2_sweep_steps;
        } else {
                leds->pwm_2_enabled     = false;
        }
}

void led_pwm_add_ticks(struct led_pwm_state *leds, uint32_t elapsed_us)
{
        leds->uptime_us += elapsed_us;
}

bool led_pwm_update_leds(struct led_pwm_state *leds)
{
        uint8_t led1_fraction = 128;

        /*
         * Compute states of emulated PWM timers
         */
        bool pwm_1_led_state = true; /* forces LED on when pwm1 is disabled */
        if (leds->pwm_1_enabled) {
                pwm_1_led_state = led_pwm_on_p(leds->pwm_1_period_us,
                                        leds->pwm_1_sweep_steps,
                                        leds->uptime_us,
                                        &led1_fraction);
        }

#ifdef PIOS_LED_ALARM
        uint8_t led2_fraction = 0;

        bool pwm_2_led_state = false; /* forces LED off when pwm2 is disabled */
        if (leds->pwm_2_enabled) {
                pwm_2_led_state = led_pwm_on_p(leds->pwm_2_period_us,
                                        leds->pwm_2_sweep_steps,
                                        leds->uptime_us,
                                        &led2_fraction);
        }
#endif

        /*
         * Toggle the LEDs based on the 2 emulated PWM timers
         */

        if (pwm_1_led_state) {
                PIOS_ANNUNC_On(PIOS_LED_HEARTBEAT);
        } else {
                PIOS_ANNUNC_Off(PIOS_LED_HEARTBEAT);
        }

#ifdef PIOS_INCLUDE_WS2811
#define WS2811_UPDATE_INTERVAL 15000    // 67Hz!

        if ((leds->uptime_us - leds->last_ws2811_us) >= WS2811_UPDATE_INTERVAL) {
                leds->last_ws2811_us = leds->uptime_us;

                PIOS_WS2811_set_all(pios_ws2811, led1_fraction / 2,
                        led2_fraction / 3, 0);
                PIOS_WS2811_trigger_update(pios_ws2811);
        }
#endif

#ifdef PIOS_LED_ALARM
        if (PIOS_LED_ALARM != PIOS_LED_HEARTBEAT) {
                if (pwm_2_led_state) {
                        PIOS_ANNUNC_On(PIOS_LED_ALARM);
                } else {
                        PIOS_ANNUNC_Off(PIOS_LED_ALARM);
                }
        }
#endif

        return true;
}