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amiro-blt / Target / Source / ARMCM4_STM32 / timer.c @ 69661903

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1 69661903 Thomas Schöpping
/************************************************************************************//**
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* \file         Source\ARMCM4_STM32\timer.c
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* \brief        Bootloader timer driver source file.
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* \ingroup      Target_ARMCM4_STM32
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* \internal
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*----------------------------------------------------------------------------------------
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*                          C O P Y R I G H T
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*----------------------------------------------------------------------------------------
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*   Copyright (c) 2013  by Feaser    http://www.feaser.com    All rights reserved
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*
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*----------------------------------------------------------------------------------------
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*                            L I C E N S E
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*----------------------------------------------------------------------------------------
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* This file is part of OpenBLT. OpenBLT is free software: you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as published by the Free
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* Software Foundation, either version 3 of the License, or (at your option) any later
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* version.
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*
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* OpenBLT is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
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* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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* PURPOSE. See the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along with OpenBLT.
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* If not, see <http://www.gnu.org/licenses/>.
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*
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* A special exception to the GPL is included to allow you to distribute a combined work 
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* that includes OpenBLT without being obliged to provide the source code for any 
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* proprietary components. The exception text is included at the bottom of the license
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* file <license.html>.
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* 
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* \endinternal
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****************************************************************************************/
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/****************************************************************************************
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* Include files
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****************************************************************************************/
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#include "boot.h"                                /* bootloader generic header          */
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#include "stm32f4xx.h"                           /* STM32 registers                    */
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/****************************************************************************************
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* Local data declarations
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****************************************************************************************/
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/** \brief Local variable for storing the number of milliseconds that have elapsed since
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 *         startup.
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 */
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static blt_int32u millisecond_counter;
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/************************************************************************************//**
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** \brief     Initializes the polling based millisecond timer driver.
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** \return    none.
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**
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****************************************************************************************/
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void TimerInit(void)
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{
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  /* reset the timer configuration */
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  TimerReset();
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  /* configure the systick frequency as a 1 ms event generator */
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  SysTick->LOAD = BOOT_CPU_SYSTEM_SPEED_KHZ - 1;
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  /* reset the current counter value */
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  SysTick->VAL = 0;
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  /* select core clock as source and enable the timer */
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  SysTick->CTRL = SysTick_CTRL_CLKSOURCE_Msk | SysTick_CTRL_ENABLE_Msk;
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  /* reset the millisecond counter value */
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  millisecond_counter = 0;
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} /*** end of TimerInit ***/
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/************************************************************************************//**
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** \brief     Reset the timer by placing the timer back into it's default reset
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**            configuration.
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** \return    none.
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**
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****************************************************************************************/
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void TimerReset(void)
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{
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  /* set the systick's status and control register back into the default reset value */
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  SysTick->CTRL = 0;
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} /* end of TimerReset */
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/************************************************************************************//**
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** \brief     Updates the millisecond timer.
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** \return    none.
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**
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****************************************************************************************/
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void TimerUpdate(void)
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{
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  /* check if the millisecond event occurred */
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  if ((SysTick->CTRL & SysTick_CTRL_COUNTFLAG_Msk) != 0)
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  {
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    /* increment the millisecond counter */
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    millisecond_counter++;
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  }
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} /*** end of TimerUpdate ***/
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/************************************************************************************//**
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** \brief     Obtains the counter value of the millisecond timer.
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** \return    Current value of the millisecond timer.
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**
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****************************************************************************************/
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blt_int32u TimerGet(void)
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{
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  /* updating timer here allows this function to be called in a loop with timeout
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   * detection.
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   */
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  TimerUpdate();
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  /* read and return the amount of milliseconds that passed since initialization */
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  return millisecond_counter;
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} /*** end of TimerGet ***/
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/*********************************** end of timer.c ************************************/