lpc17xx_systick.c

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/***********************************************************************/
/* Peripheral group ----------------------------------------------------------- */
/* 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 ----------------------------------------------------------- */
/*********************************************************************/
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;
    }
}

/*********************************************************************/
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;
    }
}

/*********************************************************************/
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;
}

/*********************************************************************/
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;
}

/*********************************************************************/
uint32_t SYSTICK_GetCurrentValue(void)
{
    return (SysTick->CURR);
}

/*********************************************************************/
void SYSTICK_ClearCounterFlag(void)
{
    SysTick->CTRL &= ~ST_CTRL_COUNTFLAG;
}
#endif /* _SYSTICK */

/* --------------------------------- End Of File ------------------------------ */