DIY - PIC： PIC18F4550 Timer1 模組程式 (廿十九)

DIY - PIC： PIC18F4550 Timer1 模組程式 (廿十九) ：

Timer1 程式是利用 PIC18F4550 內的計時器 1 及中斷來實現，程式開始是設定計時器 1 (10ms) 及中斷旗號，程式便進入循環。當時鐘上升，計時器 1 加一直至溢滿便會觸發中斷，中斷副程式將 TimeCount 加一，當 TimeCount 小於 100 LED 不閃動，但 TimeCount 大於 100 及 小於 200 LED便會閃動，大於 200 便會重置 TimeCount，完成中斷副程式後，返回程式繼續循環。

▲ Timer1 流程圖

程式：

//***** Vector Remapping ************************************************* #pragma interrupt high_isr #pragma code high_vector = 0x08 void high_interrupt (void) {            _asm goto high_isr _endasm } #pragma code //***** END Vector Remapping ******************************************** /************************************************************************* /*************************************************************************  * Function:        void main(void)  *  * PreCondition:    None  * Input:           None  * Output:          None  * Side Effects:    None  * Overview:        Main program entry point.  * Note:            None  ************************************************************************/ void main (void) {         TRISA = 0x00;                 // Port A As Output                                     // Set Timer 1          OpenTimer1         (                 TIMER_INT_ON &         // Interrupt: ON                 T1_16BIT_RW &         // 16 bit mode                 T1_SOURCE_INT &     // Use internal clock                 T1_PS_1_8 &         // Prescaler 1:1/2/4/8                 T1_OSC1EN_OFF        // No oscillator         );   //***** Vector Remapping ************************************************* #pragma interrupt high_isr #pragma code high_vector = 0x08 void high_interrupt (void) {            _asm goto high_isr _endasm } #pragma code //***** END Vector Remapping ******************************************** /************************************************************************* /*************************************************************************  * Function:        void main(void)  *  * PreCondition:    None  * Input:           None  * Output:          None  * Side Effects:    None  * Overview:        Main program entry point.  * Note:            None  ************************************************************************/ void main (void) {         TRISA = 0x00;                 // Port A As Output                                     // Set Timer 1          OpenTimer1         (                 TIMER_INT_ON &         // Interrupt: ON                 T1_16BIT_RW &         // 16 bit mode                 T1_SOURCE_INT &     // Use internal clock                 T1_PS_1_8 &         // Prescaler 1:1/2/4/8                 T1_OSC1EN_OFF        // No oscillator         );         WriteTimer1 (59286);        // Preset Timer1 value 59286         RCONbits.IPEN = 0;             // Interrupt Priority Control: OFF                                     // (RCON register IPEN bit = 0)         PIE1bits.TMR1IE = 1;         // Timer1 interrupt enable         INTCONbits.PEIE = 1;         // peripheral interrupt enable                                     // INTCON register bit b6: low interrupt enable / disable                                     // (When interrupt priority control)         INTCONbits.GIE = 1;         // all interrupt enable                                     // INTCON register bit b7: high interrupt enable / disable                                     // (When interrupt priority control)         while (1)                     // wait for interrupt doing nothing     {     } } void high_isr (void) {         PIR1bits.TMR1IF = 0;        // Timer1 interrupt flag to 0         WriteTimer1 (59286);         // 0.05μsec × 4 × 8 × 6250 = 10000μsec = 10msec                                     // (FOSC = HS at the system clock 20MHz)                                     // 256 × 256 - 6250 = 59286                                     // 16 bit timer overflow interrupt occurs         TimeCount ++;                 // 10msec for each increment         if (TimeCount <100)         // count of 100 or less (1000msec = 10msec × 100)         {                     LATAbits.LATA0 = 0;    //RA0 = 0 LED: OFF Scope=0         }         else if (TimeCount <200)         // count from 100 to 200 (2000msec = 10msec × 100)         {                  LATAbits.LATA0 = 1;    // RA0 = 1 LED: ON Scope=1         }         else TimeCount = 0;                // Reset count = 0 }

▲ Timer1 20ms (10msx2)

2011 年 03 月 05 日 天氣報告
氣溫：17.1 度 @ 23:00 
相對濕度：百分之73%  
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