1. 實(shí)驗(yàn)功能：本實(shí)驗(yàn)的功能是利用STM8單片機(jī)控制蜂鳴器發(fā)出和弦聲音。
   2. 電路原理：按鍵接PB2口，蜂鳴器接PD4口，當(dāng)按下按鍵時STM8利用TIM2的PWM模式驅(qū)動蜂鳴器就發(fā)出“123”的和弦聲音。
   3. 采用IAR FOR STM8開發(fā)環(huán)境，外部晶振16M。
   4. 程序代碼如下：

/********************************************************************************

* 文件名稱：STM8_Buzzer.c

* 開發(fā)環(huán)境：IAR FOR STM8 1.20

********************************************************************************/
#include "iostm8s105s4.h"

#define uchar                              unsigned char
#define uint                                  unsigned int

uchar SysDeal_Flag = 0;
uchar Sys_Count = 0;
uchar SendData_Flag =0;
uchar K_Flag = 0;
#define Sys_Time                      99 //100*4us = 400us
#define Sys_Prescaler             6 //2^6 = 64

#define Key_In_Power             PB_IDR_IDR2
#define Key_Delay                    10
uchar Key_In = 0;
uchar Key_Value = 0;
uchar Key_Flag = 0;

#define BELL_PWM1           640 //320us
#define BELL_PWM2           564 //282us
#define BELL_PWM3           540 //270us
#define BELL_PWM4           460 //230us
#define BELL_PWM5           408 //204us
#define Buzzer_Stop()         (TIM2_CR1 = 0x00)
#define BELL_MODE2         0
uchar Buz_Time = 0;
uchar Buz_State = 0;
uchar Buz_Mode = 0;
uchar Buz_Start = 0;
const uint BUZ_PWMTAB[][11]=  
{
  {BELL_PWM3,BELL_PWM3, BELL_PWM4,BELL_PWM4, BELL_PWM5,BELL_PWM5, 0xff,0xff,0xff,0xff,0xff}
};
const uchar BUZ_TIMETAB[][11]=
{ 
  {8,10,6,10,6,20,0xff,0xff,0xff,0xff,0xff}
};

void Delay_ms( uint ms )
{ 
  uint i,j;
  for( j=0; j  { 
    for( i=0; i<1000; i++ )
    {;} 
  }
}

void CLK_Init(void)
{
  CLK_ECKR=0x03;//外部時鐘寄存器 外部時鐘準(zhǔn)備就緒，外部時鐘開
  CLK_SWCR=0x02;//切換控制寄存器 使能切換機(jī)制
  CLK_SWR=0xB4;//主時鐘切換寄存器 選擇HSE為主時鐘源*/

  while (!(CLK_SWCR & 0x08));  
  CLK_CSSR=0x01;//時鐘安全系統(tǒng)寄存器    
}

void SysClk_Init(void)
{ 
  asm("sim");
  TIM4_IER = 0x00; //禁止中斷
  TIM4_EGR = 0x01; //允許產(chǎn)生更新事件
  TIM4_PSCR = Sys_Prescaler;
  TIM4_ARR = Sys_Time;
  TIM4_CNTR = Sys_Time;
                        //定時周期= 400us
  TIM4_CR1 = 0x01;
  TIM4_IER = 0x01;
  asm("rim");
}

#pragma vector = TIM4_OVR_UIF_vector
__interrupt void TIM4_OVR_UIF(void)
{ 
  TIM4_SR = 0x00;
  Sys_Count ++;
//---------------------------------------
  if( Sys_Count % 5 == 1 )  //2ms
  { 
    SysDeal_Flag = 1; 
  }
  else if(Sys_Count  == 5)
  {
    SendData_Flag =1;
  }
  else if(Sys_Count >= 15)
  {
    Sys_Count = 0;
  }
  else
  { 
    K_Flag = 1;        
  }  
}

void Buzzer_Init(void)
{ 
  PD_DDR |= 0x90;           // 配置PD4方向?yàn)檩敵?br/>  PD_CR1 |= 0x90;           // 設(shè)置PD4推挽輸出
  PD_CR2 &= 0x6f;
  //------------------------------------
  TIM2_PSCR = 3;            //8分頻。f=16m/8=2m----0.5us
  TIM2_CCMR1 = 0x70;        // PWM 模式 2
  TIM2_CCER1 = 0x03;        // CC1配置為輸出
}

void Buzzer_Pwm(uint timenum)
{ 
  TIM2_ARRH = (uchar)(timenum>>8);
  TIM2_ARRL = (uchar)(timenum);
  TIM2_CCR1H = (uchar)(timenum>>9);
  TIM2_CCR1L = (uchar)(timenum>>1);
  TIM2_CR1 = 0x01;          // 計(jì)數(shù)器使能，開始計(jì)數(shù)
}

void Bell_DealFun(void)
{ 
  static uchar index = 0;
  switch( Buz_State )
  { 
  case 0: 
         Buz_Time = 0; 
         Buzzer_Stop(); 
         index = 0;
         if( Buz_Start == 1 )
         { 
           Buz_State ++; 
           Buzzer_Pwm( BUZ_PWMTAB[Buz_Mode][index] );
         }
         break;
  case 1: 
         Buz_Time++;
         if( Buz_Time >= BUZ_TIMETAB[Buz_Mode][index] )
         { 
           Buz_Time = 0; 
           Buz_State = 2; 
           index ++;
           if( BUZ_TIMETAB[Buz_Mode][index] == 0xff )
           { 
             Buz_State = 0; 
             Buzzer_Stop(); 
             Buz_Start = 0; 
           }
             else
             { 
               Buzzer_Pwm( BUZ_PWMTAB[Buz_Mode][index] ); 
             }
         }
         break;
  case 2: 
         Buz_Time++;
         if( Buz_Time >= BUZ_TIMETAB[Buz_Mode][index] )
         { 
           Buz_Time = 0; 
           Buz_State = 1; 
           index ++;
           if( BUZ_TIMETAB[Buz_Mode][index] == 0xff )
           { 
             Buz_State = 0; 
             Buzzer_Stop();
             Buz_Start = 0;
           }
           else
           { 
             Buzzer_Pwm( BUZ_PWMTAB[Buz_Mode][index] );
           }
         }
         break;
  default: 
         Buz_State = 0; 
         Buz_Time = 0; 
         index = 0;
         break;
  }
}

void Buzzer_Start(uchar mode)
{ 
  if( Buz_Start == 0 )
  { 
    Buz_Mode = mode; 
    Buz_Start = 1; 
  }
}

void Get_Key(void)
{
  Key_In = 0;
  if(!Key_In_Power)
  {
    Key_In |= 0x01;
  }
}

uchar Scan_Key(void)
{ 
  static uchar Key_Task=0,Key_Count=0;
  switch( Key_Task )
  { 
  case 0: 
          if( Key_In != 0 )
          { 
            Key_Task = 1; 
            Key_Count = 0; 
          } 
       break;
  case 1: 
          Key_Count++;
          if( Key_Count >= Key_Delay )
          { 
            Key_Task = 2; 
            Key_Count = 0; 
          }
          break;
  case 2: 
          if( Key_In != 0 )
          { 
            Key_Task = 3; 
            Key_Count = 0; 
            Key_Value = Key_In; 
            return(1); 
          }
          else
          { 
            Key_Task = 0; 
          }
          break;
  case 3: 
          if( Key_In == 0 )
          { 
            Key_Task = 0; 
            Key_Count = 0; 
          } 
          break;
  default: 
          Key_Task = 0; 
          Key_Count = 0; 
          break;
  }   
  return(0);
}