//------------------------------------------------------------------------------------
// Includes
//------------------------------------------------------------------------------------
#include <c8051f020.h>                    // SFR declarations
//------------------------------------------------------------------------------------
// Global CONSTANTS
//------------------------------------------------------------------------------------

#define SYSCLK 2000000                    // approximate SYSCLK frequency in Hz

sbit  LED1 = P1^6;                         // green LED: '1' = ON; '0' = OFF
sbit  LED2 = P3^5; 
sbit  LED3 = P3^6; 
//------------------------------------------------------------------------------------
// Function PROTOTYPES
//------------------------------------------------------------------------------------
void PORT_Init (void);


void SYSCLK_Init ()
{
    int i;                    // 延時計數(shù)器
    OSCXCN = 0x67;            // 開啟外部振蕩器24.000000MHz晶體
    for (i=0; i < 256; i++) ; // 等待振蕩器啟振
    while (!(OSCXCN & 0x80)); // 等待晶體振蕩器穩(wěn)定
    OSCICN = 0x88;            // 選擇外部振蕩器為系統(tǒng)時鐘源并允許丟失
}
void PORT_Init (void)
{
   //XBR2    = 0x40;                     // Enable crossbar and weak pull-ups
  //  XBR0      = 0x07;
  //  XBR1      = 0x80;
    XBR2      = 0x40;
   //P1MDOUT |= 0x40;                    // enable P1.6 (LED) as push-pull output
}

//------------------------------------------------------------------------------------
// MAIN Routine
//------------------------------------------------------------------------------------
void main (void) {
   // disable watchdog timer
   WDTCN = 0xde;
   WDTCN = 0xad;
   SYSCLK_Init ();
   PORT_Init ();
   
   //EX7 中斷配置
	P3IF|=0x80;
	EIE2|=0x20;
   //Timer2 mode0 config
   CKCON&=~0x20;
   T2CON=0x09;
   TL2=0;
   TH2=0;
   ET2=1;
   //enable interrupt
	EA=1;
   while(1);

}
//上升沿中斷處理程序
void ex7_ISR(void)interrupt 19 using 1
{
	P3IF&=~0x80;
	//開啟定時器
	TR2=1;
}

//捕捉中斷服務(wù)程序
void cap_ISR(void) interrupt 5 using 2
{
	unsigned char temp;
	EXF2=0;
	TR2=0;
   	TL2=0;
   	TH2=0;
	//RCAP2H RCAP2L
	//1 1 0 0, 0 0 0 0, 0 0 0 0, 0 0 0 0   
	temp=RCAP2H;
	if(temp&0x80==0x80)
		LED1=0;
	else
		LED1=1;
	if(temp&0x40==0x40)
		LED2=0;
	else
		LED2=1;
	if(temp&0x20==0x20)
		LED3=0;
	else
		LED3=1;
	//計算脈沖寬度
	//根據(jù)結(jié)果顯示
}


//step 1 用上升，開啟定時器

//step 2 下降沿捕捉

//step 3 計算脈沖寬度,根據(jù)一定規(guī)則輸出到LED