140 lines
6.0 KiB
C
140 lines
6.0 KiB
C
/************************************************************************************//**
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* \file Source/ARMCM3_EFM32/timer.c
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* \brief Bootloader timer driver source file.
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* \ingroup Target_ARMCM3_EFM32
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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) 2012 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 have received a copy of the GNU General Public License along with OpenBLT. It
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* should be located in ".\Doc\license.html". If not, contact Feaser to obtain a copy.
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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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/****************************************************************************************
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* Type definitions
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****************************************************************************************/
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/** \brief Systick registers. */
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typedef struct
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{
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volatile blt_int32u CTRL; /**< SysTick Control and Status Register */
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volatile blt_int32u LOAD; /**< SysTick Reload Value Register */
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volatile blt_int32u VAL; /**< SysTick Current Value Register */
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} tSysTickRegs;
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/****************************************************************************************
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* Macro definitions
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****************************************************************************************/
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/** \brief CLKSOURCE bit of the system tick. */
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#define SYSTICK_BIT_CLKSOURCE ((blt_int32u)0x00000004)
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/** \brief ENABLE bit of the system tick. */
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#define SYSTICK_BIT_ENABLE ((blt_int32u)0x00000001)
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/** \brief COUNTERFLAG bit of the system tick. */
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#define SYSTICK_BIT_COUNTERFLAG ((blt_int32u)0x00010000)
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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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* Register definitions
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****************************************************************************************/
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/** \brief Macro to access the system tick registers. */
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#define SYSTICK ((tSysTickRegs *) (blt_int32u)0xE000E010)
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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_BIT_CLKSOURCE | SYSTICK_BIT_ENABLE;
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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_BIT_COUNTERFLAG) != 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 ************************************/
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