AMiRo-OS

/************************************************************************************//**

* \file         Source\ARMCM3_STM32\timer.c

* \brief        Bootloader timer driver source file.

* \ingroup      Target_ARMCM3_STM32

* \internal

*----------------------------------------------------------------------------------------

*                          C O P Y R I G H T

*----------------------------------------------------------------------------------------

*   Copyright (c) 2011  by Feaser    http://www.feaser.com    All rights reserved

*

*----------------------------------------------------------------------------------------

*                            L I C E N S E

*----------------------------------------------------------------------------------------

* This file is part of OpenBLT. OpenBLT 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.

*

* OpenBLT 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 OpenBLT.

* If not, see <http://www.gnu.org/licenses/>.

*

* A special exception to the GPL is included to allow you to distribute a combined work 

* that includes OpenBLT without being obliged to provide the source code for any 

* proprietary components. The exception text is included at the bottom of the license

* file <license.html>.

* 

* \endinternal

****************************************************************************************/

/****************************************************************************************

* Include files

****************************************************************************************/

#include "boot.h"                                /* bootloader generic header          */

/****************************************************************************************

* Type definitions

****************************************************************************************/

/** \brief Systick registers. */

typedef struct

{

  volatile blt_int32u CTRL;                   /**< SysTick Control and Status Register */

  volatile blt_int32u LOAD;                   /**< SysTick Reload Value Register       */

  volatile blt_int32u VAL;                    /**< SysTick Current Value Register      */

} tSysTickRegs;

/****************************************************************************************

* Macro definitions

****************************************************************************************/

/** \brief CLKSOURCE bit of the system tick. */

#define SYSTICK_BIT_CLKSOURCE    ((blt_int32u)0x00000004)

/** \brief ENABLE bit of the system tick. */

#define SYSTICK_BIT_ENABLE       ((blt_int32u)0x00000001)

/** \brief COUNTERFLAG bit of the system tick. */

#define SYSTICK_BIT_COUNTERFLAG  ((blt_int32u)0x00010000)

/****************************************************************************************

* Local data declarations

****************************************************************************************/

/** \brief Local variable for storing the number of milliseconds that have elapsed since

 *         startup.

 */

static blt_int32u millisecond_counter;

/****************************************************************************************

* Register definitions

****************************************************************************************/

/** \brief Macro to access the system tick registers. */

#define SYSTICK          ((tSysTickRegs *) (blt_int32u)0xE000E010)

/************************************************************************************//**

** \brief     Initializes the polling based millisecond timer driver.

** \return    none.

**

****************************************************************************************/

void TimerInit(void)

{

  /* reset the timer configuration */

  TimerReset();

  /* configure the systick frequency as a 1 ms event generator */

  SYSTICK->LOAD = BOOT_CPU_SYSTEM_SPEED_KHZ - 1;

  /* reset the current counter value */

  SYSTICK->VAL = 0;

  /* select core clock as source and enable the timer */

  SYSTICK->CTRL = SYSTICK_BIT_CLKSOURCE | SYSTICK_BIT_ENABLE;

  /* reset the millisecond counter value */

  millisecond_counter = 0;

} /*** end of TimerInit ***/

/************************************************************************************//**

** \brief     Reset the timer by placing the timer back into it's default reset

**            configuration.

** \return    none.

**

****************************************************************************************/

void TimerReset(void)

{

  /* set the systick's status and control register back into the default reset value */

  SYSTICK->CTRL = 0;

} /* end of TimerReset */

/************************************************************************************//**

** \brief     Updates the millisecond timer.

** \return    none.

**

****************************************************************************************/

void TimerUpdate(void)

{

  /* check if the millisecond event occurred */

  if ((SYSTICK->CTRL & SYSTICK_BIT_COUNTERFLAG) != 0)

  {

    /* increment the millisecond counter */

    millisecond_counter++;

  }

} /*** end of TimerUpdate ***/

/************************************************************************************//**

** \brief     Obtains the counter value of the millisecond timer.

** \return    Current value of the millisecond timer.

**

****************************************************************************************/

blt_int32u TimerGet(void)

{

  /* updating timer here allows this function to be called in a loop with timeout

   * detection.

   */

  TimerUpdate();

  /* read and return the amount of milliseconds that passed since initialization */

  return millisecond_counter;

} /*** end of TimerGet ***/

/*********************************** end of timer.c ************************************/