LibrePilot/flight/libraries/stopwatch.c

/**
 ******************************************************************************
 * @addtogroup CopterControlBL CopterControl BootLoader
 * @{
 *
 * @file       stopwatch.c
 * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
 * @brief      Timer functions for the LED PWM.
 * @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 files
/////////////////////////////////////////////////////////////////////////////

#include "stm32f10x_tim.h"

/////////////////////////////////////////////////////////////////////////////
// Local definitions
/////////////////////////////////////////////////////////////////////////////

uint32_t STOPWATCH_Init(u32 resolution, TIM_TypeDef *TIM)
{
    uint32_t STOPWATCH_TIMER_RCC;

    switch ((uint32_t)TIM) {
    case (uint32_t)TIM1:
        STOPWATCH_TIMER_RCC = RCC_APB2Periph_TIM1;
        break;
    case (uint32_t)TIM2:
        STOPWATCH_TIMER_RCC = RCC_APB1Periph_TIM2;
        break;
    case (uint32_t)TIM3:
        STOPWATCH_TIMER_RCC = RCC_APB1Periph_TIM3;
        break;
    case (uint32_t)TIM4:
        STOPWATCH_TIMER_RCC = RCC_APB1Periph_TIM4;
        break;
    case (uint32_t)TIM5:
        STOPWATCH_TIMER_RCC = RCC_APB1Periph_TIM5;
        break;
    case (uint32_t)TIM6:
        STOPWATCH_TIMER_RCC = RCC_APB1Periph_TIM6;
        break;
    case (uint32_t)TIM7:
        STOPWATCH_TIMER_RCC = RCC_APB1Periph_TIM7;
        break;
    case (uint32_t)TIM8:
        STOPWATCH_TIMER_RCC = RCC_APB2Periph_TIM8;
        break;
    default:
        /* Unsupported timer */
        while (1) {
            ;
        }
    }

    // enable timer clock
    if (STOPWATCH_TIMER_RCC == RCC_APB2Periph_TIM1 || STOPWATCH_TIMER_RCC
        == RCC_APB2Periph_TIM8) {
        RCC_APB2PeriphClockCmd(STOPWATCH_TIMER_RCC, ENABLE);
    } else {
        RCC_APB1PeriphClockCmd(STOPWATCH_TIMER_RCC, ENABLE);
    }

    // time base configuration
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    TIM_TimeBaseStructure.TIM_Period        = 0xffff; // max period
    TIM_TimeBaseStructure.TIM_Prescaler     = (72 * resolution) - 1; // <resolution> uS accuracy @ 72 MHz
    TIM_TimeBaseStructure.TIM_ClockDivision = 0;
    TIM_TimeBaseStructure.TIM_CounterMode   = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM, &TIM_TimeBaseStructure);

    // enable interrupt request
    TIM_ITConfig(TIM, TIM_IT_Update, ENABLE);

    // start counter
    TIM_Cmd(TIM, ENABLE);

    return 0; // no error
}

/////////////////////////////////////////////////////////////////////////////
// ! Resets the stopwatch
// ! \return < 0 on errors
/////////////////////////////////////////////////////////////////////////////
uint32_t STOPWATCH_Reset(TIM_TypeDef *TIM)
{
    // reset counter
    TIM->CNT = 1; // set to 1 instead of 0 to avoid new IRQ request
    TIM_ClearITPendingBit(TIM, TIM_IT_Update);

    return 0; // no error
}

/////////////////////////////////////////////////////////////////////////////
// ! Returns current value of stopwatch
// ! \return 1..65535: valid stopwatch value
// ! \return 0xffffffff: counter overrun
/////////////////////////////////////////////////////////////////////////////
uint32_t STOPWATCH_ValueGet(TIM_TypeDef *TIM)
{
    uint32_t value = TIM->CNT;

    if (TIM_GetITStatus(TIM, TIM_IT_Update) != RESET) {
        value = 0xffffffff;
    }

    return value;
}