鋸齒波：

 

#include <c8051f330.h>                  
#include <stdio.h>
//-----------------------------------------------------------------------------
// 定義16位寄存器
//-----------------------------------------------------------------------------
sfr16 DAC0     = 0x96;                 // 10位DAC寄存器地址
sfr16 TMR3RL   = 0xca;                 //  定時(shí)器3數(shù)據(jù)寄存器地址
sfr16 TMR3     = 0xCC;                 //  定時(shí)器3計(jì)數(shù)寄存器
//常量賦值
//-----------------------------------------------------------------------------
#define SYSCLK       49000000         
#define SAMPLE_RATE  50000 
// 定義函數(shù)
//------------------------------------------------------------------------------------
void SYSCLK_Init (void);
void PORT_Init (void);
void Timer3_Init (int counts);
void DAC0_Init(void);
void Timer3_ISR (void);
void DAC0_CNVS_DAC0h(void);
// 定義全局變量
//-----------------------------------------------------------------------------

long int i=0;                       

// 函數(shù)
//------------------------------------------------------------------------------------
void main (void)
 {
   PCA0MD &= ~0x40;                                //關(guān)閉看門狗  
   SYSCLK_Init ();                                 //系統(tǒng)時(shí)鐘初始化
   PORT_Init ();                                   //I/O口初始化   
 
   Timer3_Init (SYSCLK/SAMPLE_RATE);  //定時(shí)器3溢出作為DAC的轉(zhuǎn)換啟動(dòng)信號(hào)
   DAC0_Init();                                   
   EA=1;
   while(1)
         {  
          }
}
 // 端口初始化
//------------------------------------------------------------------------------------

void PORT_Init (void)
{
   P0SKIP  |= 0x41;             
   XBR1    = 0x40;               
}
//-----------------------------------------------------------------------------
// 系統(tǒng)時(shí)鐘初始化
//-----------------------------------------------------------------------------

void SYSCLK_Init (void)
{
   OSCICN |= 0x03;          //SYSCLK為內(nèi)部H-F振蕩器的頻率           
   RSTSRC  = 0x04;                    
}
//-----------------------------------------------------------------------------
// 定時(shí)器3初始化
//-----------------------------------------------------------------------------

void Timer3_Init (int counts)
{   
   TMR3CN = 0x00;                                    
   CKCON |= 0x40;                    
   TMR3RL  = -counts;              
   TMR3    = TMR3RL;                 
   EIE1 |= 0x80;                     
   TMR3CN |= 0x04;       
}

// 數(shù)模轉(zhuǎn)換初始化
//-----------------------------------------------------------------------------
void DAC0_Init (void)
 {
   IDA0CN = 0xb2;       //設(shè)置為0x82,0x92,0xa2,0xb2時(shí)分別是用定時(shí)器0，1,，2,，3          
   REF0CN = 0x03;       //的溢出作為IDAC的更新輸出          
  }

// 外部觸發(fā)轉(zhuǎn)換程序
//-----------------------------------------------------------------------------

void DAC0_CNVS_DAC0h(void)
{ 
    IDA0H=i;                           
   i=i+16;
   if(i==0xffff)
   {
   i=0;}
}
 //-----------------------------------------------------------------------------
//  定時(shí)器3中斷
//-----------------------------------------------------------------------------

void Timer3_ISR (void) interrupt 14
{    TMR3CN &= ~0x80;                             
   DAC0=i;
   i=i+16;
   if(i==0xfff)
   {
   i=0;}
}