File content as of revision 149:156823d33999:

/**************************************************************************//**
 * @file     timer.c
 * @version  V1.00
 * $Revision: 6 $
 * $Date: 14/05/29 1:13p $
 * @brief    NUC472/NUC442 TIMER driver source file
 *
 * @note
 * Copyright (C) 2013 Nuvoton Technology Corp. All rights reserved.
*****************************************************************************/
#include "NUC472_442.h"

/** @addtogroup NUC472_442_Device_Driver NUC472/NUC442 Device Driver
  @{
*/

/** @addtogroup NUC472_442_TIMER_Driver TIMER Driver
  @{
*/


/** @addtogroup NUC472_442_TIMER_EXPORTED_FUNCTIONS TIMER Exported Functions
  @{
*/

/**
  * @brief This API is used to configure timer to operate in specified mode
  *        and frequency. If timer cannot work in target frequency, a closest
  *        frequency will be chose and returned.
  * @param[in] timer The base address of Timer module
  * @param[in] u32Mode Operation mode. Possible options are
  *                 - \ref TIMER_ONESHOT_MODE
  *                 - \ref TIMER_PERIODIC_MODE
  *                 - \ref TIMER_TOGGLE_MODE
  *                 - \ref TIMER_CONTINUOUS_MODE
  * @param[in] u32Freq Target working frequency
  * @return Real Timer working frequency
  * @note After calling this API, Timer is \b NOT running yet. But could start timer running be calling
  *       \ref TIMER_Start macro or program registers directly
  */
uint32_t TIMER_Open(TIMER_T *timer, uint32_t u32Mode, uint32_t u32Freq)
{
    uint32_t u32Clk = TIMER_GetModuleClock(timer);
    uint32_t u32Cmpr = 0, u32Prescale = 0;

    // Fastest possible timer working freq is u32Clk / 2. While cmpr = 2, pre-scale = 0
    if(u32Freq > (u32Clk / 2)) {
        u32Cmpr = 2;
    } else {
        if(u32Clk >= 0x4000000) {
            u32Prescale = 7;    // real prescaler value is 8
            u32Clk >>= 3;
        } else if(u32Clk >= 0x2000000) {
            u32Prescale = 3;    // real prescaler value is 4
            u32Clk >>= 2;
        } else if(u32Clk >= 0x1000000) {
            u32Prescale = 1;    // real prescaler value is 2
            u32Clk >>= 1;
        }

        u32Cmpr = u32Clk / u32Freq;
    }

    timer->CTL = u32Mode | u32Prescale;
    timer->CMP = u32Cmpr;

    return(u32Clk / (u32Cmpr * (u32Prescale + 1)));
}

/**
  * @brief This API stops Timer counting and disable the Timer interrupt function
  * @param[in] timer The base address of Timer module
  * @return None
  */
void TIMER_Close(TIMER_T *timer)
{
    timer->CTL = 0;
    timer->EXTCTL = 0;

}

/**
  * @brief This API is used to create a delay loop for u32usec micro seconds
  * @param[in] timer The base address of Timer module
  * @param[in] u32Usec Delay period in micro seconds with 10 usec every step. Valid values are between 10~1000000 (10 micro second ~ 1 second)
  * @return None
  * @note This API overwrites the register setting of the timer used to count the delay time.
  * @note This API use polling mode. So there is no need to enable interrupt for the timer module used to generate delay
  */
void TIMER_Delay(TIMER_T *timer, uint32_t u32Usec)
{
    uint32_t u32Clk = TIMER_GetModuleClock(timer);
    uint32_t u32Prescale = 0, delay = SystemCoreClock / u32Clk + 1;
    double fCmpr;

    // Clear current timer configuration
    timer->CTL = 0;
    timer->EXTCTL = 0;

    if(u32Clk == 10000) {         // min delay is 100us if timer clock source is LIRC 10k
        u32Usec = ((u32Usec + 99) / 100) * 100;
    } else {    // 10 usec every step
        u32Usec = ((u32Usec + 9) / 10) * 10;
    }

    if(u32Clk >= 0x4000000) {
        u32Prescale = 7;    // real prescaler value is 8
        u32Clk >>= 3;
    } else if(u32Clk >= 0x2000000) {
        u32Prescale = 3;    // real prescaler value is 4
        u32Clk >>= 2;
    } else if(u32Clk >= 0x1000000) {
        u32Prescale = 1;    // real prescaler value is 2
        u32Clk >>= 1;
    }

    // u32Usec * u32Clk might overflow if using uint32_t
    fCmpr = ((double)u32Usec * (double)u32Clk) / 1000000.0;

    timer->CMP = (uint32_t)fCmpr;
    timer->CTL = TIMER_CTL_CNTEN_Msk | u32Prescale; // one shot mode

    // When system clock is faster than timer clock, it is possible timer active bit cannot set in time while we check it.
    // And the while loop below return immediately, so put a tiny delay here allowing timer start counting and raise active flag.
    for(; delay > 0; delay--) {
        __NOP();
    }

    while(timer->CTL & TIMER_CTL_ACTSTS_Msk);

}

/**
  * @brief This API is used to enable timer capture function with specified mode and capture edge
  * @param[in] timer The base address of Timer module
  * @param[in] u32CapMode Timer capture mode. Could be
  *                 - \ref TIMER_CAPTURE_FREE_COUNTING_MODE
  *                 - \ref TIMER_CAPTURE_COUNTER_RESET_MODE
  * @param[in] u32Edge Timer capture edge. Possible values are
  *                 - \ref TIMER_CAPTURE_FALLING_EDGE
  *                 - \ref TIMER_CAPTURE_RISING_EDGE
  *                 - \ref TIMER_CAPTURE_FALLING_THEN_RISING_EDGE
  *                 - \ref TIMER_CAPTURE_RISING_THEN_FALLING_EDGE
  * @return None
  * @note Timer frequency should be configured separately by using \ref TIMER_Open API, or program registers directly
  */
void TIMER_EnableCapture(TIMER_T *timer, uint32_t u32CapMode, uint32_t u32Edge)
{

    timer->EXTCTL = (timer->EXTCTL & ~(TIMER_EXTCTL_CAPFUNCS_Msk |
                                       TIMER_EXTCTL_CAPEDGE_Msk)) |
                    u32CapMode | u32Edge | TIMER_EXTCTL_CAPEN_Msk;
}

/**
  * @brief This API is used to disable the Timer capture function
  * @param[in] timer The base address of Timer module
  * @return None
  */
void TIMER_DisableCapture(TIMER_T *timer)
{
    timer->EXTCTL &= ~TIMER_EXTCTL_CAPEN_Msk;

}

/**
  * @brief This function is used to enable the Timer counter function with specify detection edge
  * @param[in] timer The base address of Timer module
  * @param[in] u32Edge Detection edge of counter pin. Could be ether
  *             - \ref TIMER_COUNTER_RISING_EDGE, or
  *             - \ref TIMER_COUNTER_FALLING_EDGE
  * @return None
  * @note Timer compare value should be configured separately by using \ref TIMER_SET_CMP_VALUE macro or program registers directly.
  * @note While using event counter function, \ref TIMER_TOGGLE_MODE cannot set as timer operation mode.
  */
void TIMER_EnableEventCounter(TIMER_T *timer, uint32_t u32Edge)
{
    timer->EXTCTL = (timer->EXTCTL & ~TIMER_EXTCTL_CNTPHASE_Msk) | u32Edge;
    timer->CTL |= TIMER_CTL_EXTCNTEN_Msk;
}

/**
  * @brief This API is used to disable the Timer event counter function.
  * @param[in] timer The base address of Timer module
  * @return None
  */
void TIMER_DisableEventCounter(TIMER_T *timer)
{
    timer->CTL &= ~TIMER_CTL_EXTCNTEN_Msk;
}

/**
  * @brief This API is used to get the clock frequency of Timer
  * @param[in] timer The base address of Timer module
  * @return Timer clock frequency
  * @note This API cannot return correct clock rate if timer source is external clock input.
  */
uint32_t TIMER_GetModuleClock(TIMER_T *timer)
{
    uint32_t u32Src;
    const uint32_t au32Clk[] = {__HXT, __LXT, 0, 0, 0, __LIRC, 0, __HIRC};

    if(timer == TIMER0)
        u32Src = (CLK->CLKSEL1 & CLK_CLKSEL1_TMR0SEL_Msk) >> CLK_CLKSEL1_TMR0SEL_Pos;
    else if(timer == TIMER1)
        u32Src = (CLK->CLKSEL1 & CLK_CLKSEL1_TMR1SEL_Msk) >> CLK_CLKSEL1_TMR1SEL_Pos;
    else if(timer == TIMER2)
        u32Src = (CLK->CLKSEL1 & CLK_CLKSEL1_TMR2SEL_Msk) >> CLK_CLKSEL1_TMR2SEL_Pos;
    else  // Timer 3
        u32Src = (CLK->CLKSEL1 & CLK_CLKSEL1_TMR3SEL_Msk) >> CLK_CLKSEL1_TMR3SEL_Pos;

    if(u32Src == 2) {
        if(CLK->CLKSEL0 &  CLK_CLKSEL0_PCLKSEL_Msk)
            return(SystemCoreClock / 2);
        else
            return(SystemCoreClock);
    }

    return(au32Clk[u32Src]);

}

/*@}*/ /* end of group NUC472_442_TIMER_EXPORTED_FUNCTIONS */

/*@}*/ /* end of group NUC472_442_TIMER_Driver */

/*@}*/ /* end of group NUC472_442_Device_Driver */

/*** (C) COPYRIGHT 2013 Nuvoton Technology Corp. ***/