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