LibrePilot/flight/pios/stm32f10x/pios_pwm.c

/**
 ******************************************************************************
 * @addtogroup PIOS PIOS Core hardware abstraction layer
 * @{
 * @addtogroup   PIOS_PWM PWM Input Functions
 * @brief		Code to measure with PWM input
 * @{
 *
 * @file       pios_pwm.c
 * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
 * @brief      PWM Input functions (STM32 dependent)
 * @see        The GNU Public License (GPL) Version 3
 *
 *****************************************************************************/
/*
 * 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, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include "pios.h"

#ifdef PIOS_INCLUDE_PWM

#include "pios_pwm_priv.h"


/* Provide a RCVR driver */
static int32_t PIOS_PWM_Get(uint32_t rcvr_id, uint8_t channel);

const struct pios_rcvr_driver pios_pwm_rcvr_driver = {
    .read = PIOS_PWM_Get,
};

/* Local Variables */
/* 100 ms timeout without updates on channels */
static const uint32_t PWM_SUPERVISOR_TIMEOUT = 100000;

enum pios_pwm_dev_magic {
    PIOS_PWM_DEV_MAGIC = 0xab30293c,
};

struct pios_pwm_dev {
    enum pios_pwm_dev_magic   magic;
    const struct pios_pwm_cfg *cfg;

    uint8_t  CaptureState[PIOS_PWM_NUM_INPUTS];
    uint16_t RiseValue[PIOS_PWM_NUM_INPUTS];
    uint16_t FallValue[PIOS_PWM_NUM_INPUTS];
    uint32_t CaptureValue[PIOS_PWM_NUM_INPUTS];
    uint32_t CapCounter[PIOS_PWM_NUM_INPUTS];
    uint32_t us_since_update[PIOS_PWM_NUM_INPUTS];
};

static bool PIOS_PWM_validate(struct pios_pwm_dev *pwm_dev)
{
    return pwm_dev->magic == PIOS_PWM_DEV_MAGIC;
}

#if defined(PIOS_INCLUDE_FREERTOS)
static struct pios_pwm_dev *PIOS_PWM_alloc(void)
{
    struct pios_pwm_dev *pwm_dev;

    pwm_dev = (struct pios_pwm_dev *)pios_malloc(sizeof(*pwm_dev));
    if (!pwm_dev) {
        return NULL;
    }

    pwm_dev->magic = PIOS_PWM_DEV_MAGIC;
    return pwm_dev;
}
#else
static struct pios_pwm_dev pios_pwm_devs[PIOS_PWM_MAX_DEVS];
static uint8_t pios_pwm_num_devs;
static struct pios_pwm_dev *PIOS_PWM_alloc(void)
{
    struct pios_pwm_dev *pwm_dev;

    if (pios_pwm_num_devs >= PIOS_PWM_MAX_DEVS) {
        return NULL;
    }

    pwm_dev = &pios_pwm_devs[pios_pwm_num_devs++];
    pwm_dev->magic = PIOS_PWM_DEV_MAGIC;

    return pwm_dev;
}
#endif /* if defined(PIOS_INCLUDE_FREERTOS) */

static void PIOS_PWM_tim_overflow_cb(uint32_t id, uint32_t context, uint8_t channel, uint16_t count);
static void PIOS_PWM_tim_edge_cb(uint32_t id, uint32_t context, uint8_t channel, uint16_t count);
static const struct pios_tim_callbacks tim_callbacks = {
    .overflow = PIOS_PWM_tim_overflow_cb,
    .edge     = PIOS_PWM_tim_edge_cb,
};

/**
 * Initialises all the pins
 */
int32_t PIOS_PWM_Init(uint32_t *pwm_id, const struct pios_pwm_cfg *cfg)
{
    PIOS_DEBUG_Assert(pwm_id);
    PIOS_DEBUG_Assert(cfg);

    struct pios_pwm_dev *pwm_dev;

    pwm_dev = (struct pios_pwm_dev *)PIOS_PWM_alloc();
    if (!pwm_dev) {
        goto out_fail;
    }

    /* Bind the configuration to the device instance */
    pwm_dev->cfg = cfg;

    for (uint8_t i = 0; i < PIOS_PWM_NUM_INPUTS; i++) {
        /* Flush counter variables */
        pwm_dev->CaptureState[i] = 0;
        pwm_dev->RiseValue[i]    = 0;
        pwm_dev->FallValue[i]    = 0;
        pwm_dev->CaptureValue[i] = PIOS_RCVR_TIMEOUT;
    }

    uint32_t tim_id;
    if (PIOS_TIM_InitChannels(&tim_id, cfg->channels, cfg->num_channels, &tim_callbacks, (uint32_t)pwm_dev)) {
        return -1;
    }

    /* Configure the channels to be in capture/compare mode */
    for (uint8_t i = 0; i < cfg->num_channels; i++) {
        const struct pios_tim_channel *chan   = &cfg->channels[i];

        /* Configure timer for input capture */
        TIM_ICInitTypeDef TIM_ICInitStructure = cfg->tim_ic_init;
        TIM_ICInitStructure.TIM_Channel = chan->timer_chan;
        TIM_ICInit(chan->timer, &TIM_ICInitStructure);

        /* Enable the Capture Compare Interrupt Request */
        switch (chan->timer_chan) {
        case TIM_Channel_1:
            TIM_ITConfig(chan->timer, TIM_IT_CC1, ENABLE);
            break;
        case TIM_Channel_2:
            TIM_ITConfig(chan->timer, TIM_IT_CC2, ENABLE);
            break;
        case TIM_Channel_3:
            TIM_ITConfig(chan->timer, TIM_IT_CC3, ENABLE);
            break;
        case TIM_Channel_4:
            TIM_ITConfig(chan->timer, TIM_IT_CC4, ENABLE);
            break;
        }

        // Need the update event for that timer to detect timeouts
        TIM_ITConfig(chan->timer, TIM_IT_Update, ENABLE);
    }

    *pwm_id = (uint32_t)pwm_dev;

    return 0;

out_fail:
    return -1;
}

/**
 * Get the value of an input channel
 * \param[in] channel Number of the channel desired (zero based)
 * \output PIOS_RCVR_INVALID channel not available
 * \output PIOS_RCVR_TIMEOUT failsafe condition or missing receiver
 * \output >=0 channel value
 */
static int32_t PIOS_PWM_Get(uint32_t rcvr_id, uint8_t channel)
{
    struct pios_pwm_dev *pwm_dev = (struct pios_pwm_dev *)rcvr_id;

    if (!PIOS_PWM_validate(pwm_dev)) {
        /* Invalid device specified */
        return PIOS_RCVR_INVALID;
    }

    if (channel >= PIOS_PWM_NUM_INPUTS) {
        /* Channel out of range */
        return PIOS_RCVR_INVALID;
    }
    return pwm_dev->CaptureValue[channel];
}

static void PIOS_PWM_tim_overflow_cb(__attribute__((unused)) uint32_t tim_id, uint32_t context, uint8_t channel, uint16_t count)
{
    struct pios_pwm_dev *pwm_dev = (struct pios_pwm_dev *)context;

    if (!PIOS_PWM_validate(pwm_dev)) {
        /* Invalid device specified */
        return;
    }

    if (channel >= pwm_dev->cfg->num_channels) {
        /* Channel out of range */
        return;
    }

    pwm_dev->us_since_update[channel] += count;
    if (pwm_dev->us_since_update[channel] >= PWM_SUPERVISOR_TIMEOUT) {
        pwm_dev->CaptureState[channel]    = 0;
        pwm_dev->RiseValue[channel]       = 0;
        pwm_dev->FallValue[channel]       = 0;
        pwm_dev->CaptureValue[channel]    = PIOS_RCVR_TIMEOUT;
        pwm_dev->us_since_update[channel] = 0;
    }
}

static void PIOS_PWM_tim_edge_cb(__attribute__((unused)) uint32_t tim_id, uint32_t context, uint8_t chan_idx, uint16_t count)
{
    /* Recover our device context */
    struct pios_pwm_dev *pwm_dev = (struct pios_pwm_dev *)context;

    if (!PIOS_PWM_validate(pwm_dev)) {
        /* Invalid device specified */
        return;
    }

    if (chan_idx >= pwm_dev->cfg->num_channels) {
        /* Channel out of range */
        return;
    }

    const struct pios_tim_channel *chan = &pwm_dev->cfg->channels[chan_idx];

    if (pwm_dev->CaptureState[chan_idx] == 0) {
        pwm_dev->RiseValue[chan_idx] = count;
        pwm_dev->us_since_update[chan_idx] = 0;
    } else {
        pwm_dev->FallValue[chan_idx] = count;
    }

    // flip state machine and capture value here
    /* Simple rise or fall state machine */
    TIM_ICInitTypeDef TIM_ICInitStructure = pwm_dev->cfg->tim_ic_init;
    if (pwm_dev->CaptureState[chan_idx] == 0) {
        /* Switch states */
        pwm_dev->CaptureState[chan_idx]    = 1;

        /* Switch polarity of input capture */
        TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Falling;
        TIM_ICInitStructure.TIM_Channel    = chan->timer_chan;
        TIM_ICInit(chan->timer, &TIM_ICInitStructure);
    } else {
        uint32_t value = 0;
        /* Capture computation */
        value = pwm_dev->us_since_update[chan_idx] + (pwm_dev->FallValue[chan_idx] - pwm_dev->RiseValue[chan_idx]);

        // From time to time glitches happens. Most of the observed case are related to missing or spurious overflows
        // happening when they are triggered very close each other.
        // The following workaround prevents them to cause troubles by filtering unacceptable values
        if (PIOS_PWM_VALID_RANGE_MAX > value && PIOS_PWM_VALID_RANGE_MIN < value) {
            pwm_dev->CaptureValue[chan_idx] = value;
        }
        /* Switch states */
        pwm_dev->CaptureState[chan_idx]    = 0;
        pwm_dev->us_since_update[chan_idx] = 0;
        /* Increase supervisor counter */
        pwm_dev->CapCounter[chan_idx]++;

        /* Switch polarity of input capture */
        TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
        TIM_ICInitStructure.TIM_Channel    = chan->timer_chan;
        TIM_ICInit(chan->timer, &TIM_ICInitStructure);
    }
}

#endif /* PIOS_INCLUDE_PWM */

/**
 * @}
 * @}
 */