193 lines
6.2 KiB
C
193 lines
6.2 KiB
C
/**********************************************************************
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* $Id$ lpc_systick.c 2011-06-02
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*//**
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* @file lpc_systick.c
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* @brief Contains all functions support for SysTick firmware library
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* on LPC
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* @version 1.0
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* @date 02. June. 2011
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* @author NXP MCU SW Application Team
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*
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* Copyright(C) 2011, 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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#ifdef __BUILD_WITH_EXAMPLE__
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#include "lpc_libcfg.h"
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#else
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#include "lpc_libcfg_default.h"
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#endif /* __BUILD_WITH_EXAMPLE__ */
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#ifdef _SYSTICK
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/* Includes ------------------------------------------------------------------- */
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#include "lpc_systick.h"
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#include "lpc_clkpwr.h"
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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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* Note: time interval parameter should be less than:
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* 1/cclk * (2^24) * 1000 (ms)
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* In this case, with cclk = 96Mhz, time interval value < 174ms
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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 = CLKPWR_GetCLK(CLKPWR_CLKTYPE_CPU);
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/* With internal CPU clock frequency for LPC178X 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)/(cclk / 1000) ;
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if(time > maxtime)
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{
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//Error loop
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while(1);
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}
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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 LPC178X 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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{
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//Error Loop
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while(1);
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}
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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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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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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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