pca_pz_test.c

PCA工作在8位脉宽调制器工作方式

/***************************************************************
功能:实现用PCA2模块上下沿捕捉试验,脉冲信号由T3定时发出，P2.4输出
	引线到P0.2输入(PCA2的入口口),PCA0、PCA1模块打开空闲不用(也可以用PCA0、PCA1)。
作者:ZDP
时间:2005-11-30
版本:V1.0
***************************************************************/
//------------------------------------------------------------------------------------
// Includes
//------------------------------------------------------------------------------------
#include <c8051f020.h>				// SFR declarations
#include <INTRINS.H>

sfr16 RCAP3    = 0x92;				// Timer3 reload value
sfr16 TMR3     = 0x94;              // Timer3 counter

#define SYSCLK 3062500              // approximate SYSCLK frequency in Hz
#define TR3	TMR3CN |=0x04			// T3 定时启动
#define TF3 TMR3CN &=~0x80			// 清T3 定时中断标致位
sbit  LED = P2^4;                   // rad LED: '1' = ON; '0' = OFF

//------------------------------------------------------------------------------------
// Function PROTOTYPES
//------------------------------------------------------------------------------------
void PORT_Init (void);
void Timer3_Init (int counts);
void Timer3_ISR (void);

//------------------------------------------------------------------------------------
// MAIN Routine
//------------------------------------------------------------------------------------
void main (void) {

   // disable watchdog timer
   WDTCN = 0xde;
   WDTCN = 0xad;

   PORT_Init ();

   Timer3_Init (SYSCLK / 12 / 10);        // Init Timer3 to generate interrupts
                                          // at a 10 Hz rate.
   EA = 1;								  // enable global interrupts

   while (1) {                            // spin forever

   }
}

//------------------------------------------------------------------------------------
// PORT_Init
//------------------------------------------------------------------------------------
//
// Configure the Crossbar and GPIO ports
//
void PORT_Init (void)
{  XBR0      = 0x18;					 //交叉开关设置
   XBR2      = 0x40;                     // Enable crossbar and weak pull-ups
   P2MDOUT   |= 0x10;                    // enable P2.4 (LED) as push-pull output
   PCA0CN    = 0x40;					 //启动PCA计数					 
   PCA0CPM2  = 0x31;					 //启用PCA2模块上下沿捕捉及中断使能

}

//------------------------------------------------------------------------------------
// Timer3_Init
//------------------------------------------------------------------------------------
//
// Configure Timer3 to auto-reload and generate an interrupt at interval
// specified by <counts> using SYSCLK/12 as its time base.
//
//
void Timer3_Init (int counts)
{
   TMR3CN = 0x00;                      // Stop Timer3; Clear TF3;
                                       // use SYSCLK/12 as timebase
   RCAP3   = -counts;                  // Init reload values
   TMR3    = 0xffff;                   // set to reload immediately
   EIE2   |= 0x01;                     // enable Timer3 interrupts
   EIE1    = 0x08;
   TR3;                                // start Timer3
}

//------------------------------------------------------------------------------------
// Interrupt Service Routines
//------------------------------------------------------------------------------------

//------------------------------------------------------------------------------------
// Timer3_ISR
//------------------------------------------------------------------------------------
// This routine changes the state of the LED whenever Timer3 overflows.
//
// NOTE: The SFRPAGE register will automatically be switched to the Timer 3 Page
// When an interrupt occurs.  SFRPAGE will return to its previous setting on exit
// from this routine.
//
void Timer3_ISR (void) interrupt 14
{
   TF3;                               	  // 清除 TF3
   LED = ~LED;                            // T3定时改变I/O的高低电位，产生脉冲信号
}
void PCA_ISR (void) interrupt 9
{  PCA0CN    &= 0x40;	//清PCA2模块中断标致位
   _nop_();				//在此设断点观察,P2.4的上、下沿变化时都会产生中断
}