实时时钟的演示：毫秒级计时输出；串口输出；中断的使用

/**************************************************************************************
龙丘MC9S12XS128 多功能开发板
Designed by Chiu Sir
E-mail:chiusir@163.com
软件版本:V1.1
最后更新:2009年2月28日
相关信息参考下列地址：
博客：  http://longqiu.21ic.org
淘宝店：http://shop36265907.taobao.com
------------------------------------
Code Warrior 4.7
Target : MC9S12XS128
Crystal: 16.000Mhz
busclock:16.000MHz
pllclock:32.000MHz

演示程序使用说明：
1.实时时钟的演示：
2.毫秒级计时输出；
3.串口输出速率：9600bps.
4.中断的使用。
*****************************************************************************************/
 
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#pragma LINK_INFO DERIVATIVE "mc9s12xs128" 

volatile dword u32_time_cnt=0;    

//====================中断函数==================================  

#pragma CODE_SEG __NEAR_SEG NON_BANKED
void interrupt 7 RTI_ISR(void) {   // 32.75ms timer overflow  
  ++u32_time_cnt;        
  PORTB_PB2=~PORTB_PB2;
  CRGFLG|=0X80;//Write 1 to clear RTIF bit  
}

// 函 数 名: void DLY_ms(word x)
// 功能描述: 毫秒级延时
void DLY_ms(int ms)  //x取值1～255；
{
  int ii,jj;
   if (ms<1) ms=1;
   for(ii=0;ii     for(jj=0;jj<2770;jj++);    //32MHz--1ms 
}
//-----------------------------------------------------
static void Port_Init(void)
{ 
    DDRA = 0xff; 
    PORTA= 0x00;         
    DDRB = 0xff;  //LED  PTB0--7,
    PORTB= 0xff;  //LEDs off 
}
//-----------------------------------------------------
static void SCI_Init(void)
{
    SCI0CR2=0x2c; //enable Receive Full Interrupt,RX enable,Tx enable
    SCI0BDH=0x00; //busclk  8MHz,19200bps,SCI0BDL=0x1a
    SCI0BDL=0x68; //SCI0BDL=busclk/(16*SCI0BDL)                  
                  //busclk 16MHz, 9600bps,SCI0BDL=0x68                  
}                
void uart_putchar(unsigned char ch)
{
  if (ch == '/n') 
  {
      while(!(SCI0SR1&0x80)) ;    
      SCI0DRL= 0x0d;            //output'CR'
     return;
  }
  while(!(SCI0SR1&0x80)) ;       //keep waiting when not empty 
  SCI0DRL=ch;
}

void putstr(char ch[])
{
  unsigned char ptr=0;
  while(ch[ptr]){
      uart_putchar((unsigned char)ch[ptr++]);
  }
}
// setup of the RTI interrupt frequency    
static void RTI_Init(void)
{              
    RTICTL=0x77;   //8x2^16 =>32,75ms,30.5175Hz                    
    //CRGINT=0X80;   //enable RTI Interrupt
    CRGINT=0X80;   //enable RTI Interrupt
}
// PLL初始化子程序   BUS Clock=16M
void setbusclock(void)
{  
   CLKSEL=0X00;    // disengage PLL to system
    PLLCTL_PLLON=1;   // turn on PLL
    SYNR=0x00 | 0x01;  // VCOFRQ[7:6];SYNDIV[5:0]
                        // fVCO= 2*fOSC*(SYNDIV + 1)/(REFDIV + 1)
                        // fPLL= fVCO/(2 × POSTDIV)
                        // fBUS= fPLL/2
                        // VCOCLK Frequency Ranges  VCOFRQ[7:6]
                        // 32MHz <= fVCO <= 48MHz    00
                        // 48MHz <  fVCO <= 80MHz    01
                        // Reserved                  10
                        // 80MHz <  fVCO <= 120MHz   11    
    REFDV=0x80 | 0x01;  // REFFRQ[7:6];REFDIV[5:0]
                        // fREF=fOSC/(REFDIV + 1)
                        // REFCLK Frequency Ranges  REFFRQ[7:6]
                        // 1MHz <= fREF <=  2MHz       00
                        // 2MHz <  fREF <=  6MHz       01
                        // 6MHz <  fREF <= 12MHz       10
                        // fREF >  12MHz               11                        
                        // pllclock=2*osc*(1+SYNR)/(1+REFDV)=32MHz;
    POSTDIV=0x00;       // 4:0, fPLL= fVCO/(2xPOSTDIV)
                        // If POSTDIV = $00 then fPLL is identical to fVCO (divide by one).
    _asm(nop);          // BUS CLOCK=16M
    _asm(nop);
    while(!(CRGFLG_LOCK==1));   //when pll is steady ,then use it;
    CLKSEL_PLLSEL =1;          //engage PLL to system; }
//-----------------------------------------------------
#pragma CODE_SEG DEFAULT
void Init_Dev(void)
{
    setbusclock();
    Port_Init();
    SCI_Init();     
    RTI_Init();
}

//====================main()==================================
#pragma CODE_SEG DEFAULT    
void main(void)   
{
  
  char  txtbuf[66]="";
  byte  u8_mintes=0;
  word  u16_sec=0,u16_ms=0;   
   
  Init_Dev(); 
  PORTB=0x00;
  putstr("/nLongQiu s.&t. Co. Ltd.");   
  putstr("/nhttp://shop36265907.taobao.com");   
  DLY_ms(1000);    
  PORTB=0xFF;
  EnableInterrupts;   
  for(;;)
  {
//----------时钟计时器---------------------------------
    u16_sec=u32_time_cnt*131/4;//理论值为32.75ms,时间计算部分 
    u16_ms=u16_sec%1000;       
    u16_sec=u16_sec/1000;   
    sprintf(txtbuf,"/n%d:%02ds-%03dms ",u8_mintes,u16_sec,u16_ms);    
    putstr(txtbuf);          
    if(u16_sec>58)
    {
      u8_mintes++;
      u32_time_cnt=0;
    }
//--------------------------------------------------------   
    PORTB_PB0=~PORTB_PB0;
    DLY_ms(50);        
  }//for(;;)
} //main