138 lines
5.7 KiB
C
138 lines
5.7 KiB
C
/************************************************************************************//**
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* \file Source/ARM7_LPC2000/timer.c
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* \brief Bootloader timer driver source file.
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* \ingroup Target_ARM7_LPC2000
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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) 2011 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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* Local data declarations
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****************************************************************************************/
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/** \brief Local variable that holds the last value of the free running counter. */
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static blt_int32u free_running_counter_last;
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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 T0MCR timer register. */
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#define T0MCR (*((volatile blt_int32u *) 0xE0004014))
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/** \brief T0CCR timer register. */
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#define T0CCR (*((volatile blt_int32u *) 0xE0004028))
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/** \brief T0PR timer register. */
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#define T0PR (*((volatile blt_int32u *) 0xE000400C))
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/** \brief T0PC timer register. */
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#define T0PC (*((volatile blt_int32u *) 0xE0004010))
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/** \brief T0TCR timer register. */
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#define T0TCR (*((volatile blt_int32u *) 0xE0004004))
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/** \brief T0TC timer register. */
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#define T0TC (*((volatile blt_int32u *) 0xE0004008))
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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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/* disable timer 0 interrupts */
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T0MCR = 0x00;
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T0CCR = 0x00;
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/* set prescaler so that free running counter runs at 1 kHz */
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T0PR = BOOT_CPU_SYSTEM_SPEED_KHZ - 1;
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/* start free running counter for timer 0 */
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T0TCR = 0x01;
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/* store the start value of the free running counter */
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free_running_counter_last = T0TC;
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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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/* reset the timer */
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T0TCR = 0;
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/* reset the prescaler */
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T0PR = 0;
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/* reset the timer counter */
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T0TC = 0;
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/* reset the prescaled counter */
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T0PC = 0;
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} /* 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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blt_int32u free_running_counter_now;
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/* update the millisecond counter */
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free_running_counter_now = T0TC;
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millisecond_counter += (free_running_counter_now - free_running_counter_last);
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/* store current free running counter value for next time around */
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free_running_counter_last = free_running_counter_now;
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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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