tick.c

来自「This code is used to TCP/IP connection I」· C语言 代码 · 共 140 行

#define TICK_INCLUDE
#include "p18f452.h"
#include "tcptask.h"

#define TICK_TEMP_VALUE_1       \
        ((CLOCK_FREQ / 4) / (TICKS_PER_SECOND * TICK_PRESCALE_VALUE))

#if TICK_TEMP_VALUE_1 > 60000
#error TICK_PER_SECOND value cannot be programmed with current CLOCK_FREQ
#error Either lower TICK_PER_SECOND or manually configure the Timer
#endif

#define TICK_TEMP_VALUE         (65535 - TICK_TEMP_VALUE_1)

#define TICK_COUNTER_HIGH       ((TICK_TEMP_VALUE >> 8) & 0xff)
#define TICK_COUNTER_LOW        (TICK_TEMP_VALUE & 0xff)

#if (TICK_PRESCALE_VALUE == 2)
    #define TIMER_PRESCALE  (0)
#elif ( TICK_PRESCALE_VALUE == 4 )
    #define TIMER_PRESCALE  (1)
#elif ( TICK_PRESCALE_VALUE == 8 )
    #define TIMER_PRESCALE  (2)
#elif ( TICK_PRESCALE_VALUE == 16 )
    #define TIMER_PRESCALE  (3)
#elif ( TICK_PRESCALE_VALUE == 32 )
    #define TIMER_PRESCALE  (4)
#elif ( TICK_PRESCALE_VALUE == 64 )
    #define TIMER_PRESCALE  (5)
#elif ( TICK_PRESCALE_VALUE == 128 )
    #define TIMER_PRESCALE  (6)
#elif ( TICK_PRESCALE_VALUE == 256 )
    #define TIMER_PRESCALE  (7)
#else
    #error Invalid TICK_PRESCALE_VALUE specified.
#endif




TICK TickCount = 0;


/*********************************************************************
 * Function:        void TickInit(void)
 *
 * PreCondition:    None
 *
 * Input:           None
 *
 * Output:          Tick manager is initialized.
 *
 * Side Effects:    None
 *
 * Overview:        Initializes Timer0 as a tick counter.
 *
 * Note:            None
 ********************************************************************/
void TickInit(void)
{
    // Start the timer.
    TMR0L = TICK_COUNTER_LOW;
    TMR0H = TICK_COUNTER_HIGH;

    // 16-BIT, internal timer, PSA set to 1:256
    T0CON = 0b00000000 | TIMER_PRESCALE;


    // Start the timer.
    T0CON_TMR0ON = 1;

    INTCON_TMR0IF = 1;
    INTCON_TMR0IE = 1;

}


/*********************************************************************
 * Function:        TICK TickGet(void)
 *
 * PreCondition:    None
 *
 * Input:           None
 *
 * Output:          Current second value is given
 *
 * Side Effects:    None
 *
 * Overview:        None
 *
 * Note:            None
 ********************************************************************/
TICK TickGet(void)
{
    return TickCount;
}


/*********************************************************************
 * Function:        void TickUpdate(void)
 *
 * PreCondition:    None
 *
 * Input:           None
 *
 * Output:          None
 *
 * Side Effects:    None
 *
 * Overview:        Internal Tick and Seconds count are updated.
 *
 * Note:            None
 ********************************************************************/
void TickUpdate(void)
{
    if ( INTCON_TMR0IF )
    {
        TMR0H = TICK_COUNTER_HIGH;
        TMR0L = TICK_COUNTER_LOW;

        TickCount++;

        // Remove this if not needed.
        // LATA4 ^= 1;

        INTCON_TMR0IF = 0;
    }
}