194 lines
6.4 KiB
C
194 lines
6.4 KiB
C
/**********************************************************************
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* $Id$ lpc17xx_systick.c 2010-05-21
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*//**
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* @file lpc17xx_systick.c
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* @brief Contains all functions support for SYSTICK firmware library
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* on LPC17xx
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* @version 2.0
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* @date 21. May. 2010
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* @author NXP MCU SW Application Team
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*
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* Copyright(C) 2010, NXP Semiconductor
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* All rights reserved.
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*
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***********************************************************************
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* Software that is described herein is for illustrative purposes only
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* which provides customers with programming information regarding the
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* products. This software is supplied "AS IS" without any warranties.
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* NXP Semiconductors assumes no responsibility or liability for the
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* use of the software, conveys no license or title under any patent,
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* copyright, or mask work right to the product. NXP Semiconductors
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* reserves the right to make changes in the software without
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* notification. NXP Semiconductors also make no representation or
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* warranty that such application will be suitable for the specified
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* use without further testing or modification.
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* Permission to use, copy, modify, and distribute this software and its
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* documentation is hereby granted, under NXP Semiconductors'
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* relevant copyright in the software, without fee, provided that it
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* is used in conjunction with NXP Semiconductors microcontrollers. This
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* copyright, permission, and disclaimer notice must appear in all copies of
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* this code.
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**********************************************************************/
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/* Peripheral group ----------------------------------------------------------- */
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/** @addtogroup SYSTICK
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* @{
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*/
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/* Includes ------------------------------------------------------------------- */
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#include "lpc17xx_systick.h"
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#include "lpc17xx_clkpwr.h"
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/* If this source file built with example, the LPC17xx FW library configuration
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* file in each example directory ("lpc17xx_libcfg.h") must be included,
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* otherwise the default FW library configuration file must be included instead
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*/
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#ifdef __BUILD_WITH_EXAMPLE__
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#include "lpc17xx_libcfg.h"
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#else
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#include "lpc17xx_libcfg_default.h"
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#endif /* __BUILD_WITH_EXAMPLE__ */
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#ifdef _SYSTICK
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/* Public Functions ----------------------------------------------------------- */
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/** @addtogroup SYSTICK_Public_Functions
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* @{
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*/
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/*********************************************************************//**
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* @brief Initial System Tick with using internal CPU clock source
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* @param[in] time time interval(ms)
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* @return None
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**********************************************************************/
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void SYSTICK_InternalInit(uint32_t time)
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{
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uint32_t cclk;
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float maxtime;
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cclk = SystemCoreClock;
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/* With internal CPU clock frequency for LPC17xx is 'SystemCoreClock'
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* And limit 24 bit for RELOAD value
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* So the maximum time can be set:
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* 1/SystemCoreClock * (2^24) * 1000 (ms)
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*/
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//check time value is available or not
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maxtime = (1<<24)/(SystemCoreClock / 1000) ;
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if(time > maxtime)
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//Error loop
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while(1);
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else
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{
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//Select CPU clock is System Tick clock source
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SysTick->CTRL |= ST_CTRL_CLKSOURCE;
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/* Set RELOAD value
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* RELOAD = (SystemCoreClock/1000) * time - 1
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* with time base is millisecond
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*/
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SysTick->LOAD = (cclk/1000)*time - 1;
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}
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}
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/*********************************************************************//**
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* @brief Initial System Tick with using external clock source
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* @param[in] freq external clock frequency(Hz)
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* @param[in] time time interval(ms)
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* @return None
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**********************************************************************/
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void SYSTICK_ExternalInit(uint32_t freq, uint32_t time)
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{
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float maxtime;
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/* With external clock frequency for LPC17xx is 'freq'
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* And limit 24 bit for RELOAD value
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* So the maximum time can be set:
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* 1/freq * (2^24) * 1000 (ms)
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*/
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//check time value is available or not
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maxtime = (1<<24)/(freq / 1000) ;
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if (time>maxtime)
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//Error Loop
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while(1);
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else
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{
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//Select external clock is System Tick clock source
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SysTick->CTRL &= ~ ST_CTRL_CLKSOURCE;
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/* Set RELOAD value
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* RELOAD = (freq/1000) * time - 1
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* with time base is millisecond
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*/
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maxtime = (freq/1000)*time - 1;
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SysTick->LOAD = (freq/1000)*time - 1;
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}
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}
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/*********************************************************************//**
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* @brief Enable/disable System Tick counter
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* @param[in] NewState System Tick counter status, should be:
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* - ENABLE
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* - DISABLE
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* @return None
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**********************************************************************/
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void SYSTICK_Cmd(FunctionalState NewState)
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{
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CHECK_PARAM(PARAM_FUNCTIONALSTATE(NewState));
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if(NewState == ENABLE)
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//Enable System Tick counter
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SysTick->CTRL |= ST_CTRL_ENABLE;
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else
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//Disable System Tick counter
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SysTick->CTRL &= ~ST_CTRL_ENABLE;
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}
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/*********************************************************************//**
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* @brief Enable/disable System Tick interrupt
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* @param[in] NewState System Tick interrupt status, should be:
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* - ENABLE
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* - DISABLE
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* @return None
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**********************************************************************/
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void SYSTICK_IntCmd(FunctionalState NewState)
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{
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CHECK_PARAM(PARAM_FUNCTIONALSTATE(NewState));
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if(NewState == ENABLE)
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//Enable System Tick counter
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SysTick->CTRL |= ST_CTRL_TICKINT;
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else
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//Disable System Tick counter
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SysTick->CTRL &= ~ST_CTRL_TICKINT;
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}
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/*********************************************************************//**
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* @brief Get current value of System Tick counter
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* @param[in] None
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* @return current value of System Tick counter
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**********************************************************************/
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uint32_t SYSTICK_GetCurrentValue(void)
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{
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return (SysTick->VAL);
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}
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/*********************************************************************//**
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* @brief Clear Counter flag
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* @param[in] None
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* @return None
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**********************************************************************/
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void SYSTICK_ClearCounterFlag(void)
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{
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SysTick->CTRL &= ~ST_CTRL_COUNTFLAG;
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}
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/**
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* @}
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*/
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#endif /* _SYSTICK */
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/**
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* @}
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*/
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/* --------------------------------- End Of File ------------------------------ */
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