用 單片機 產生方波、鋸齒波、三角波、梯形波，頻率可調

#include 
#define uchar unsigned char 
#define uint unsigned int 
unsigned char x=0,m=0,y=128; 
sbit WR_DA=P2^1; 
sbit CS_DA=P2^0;//DA與 單片機 的接口 
sbit S0=P3^0; //波形選擇，每次按下將產生不同的波形 
sbit S1=P3^1; //頻率減 
sbit S2=P3^2; //頻率加 
sbit S3=P3^3; //調節方波的占空比 
uchar code SinTab[256]={0x80,0x83,0x86,0x89,0x8d,0x90,0x93,0x96,0x99,0x9c,0x9f,0xa2,0xa5,0xa8,0xab,0xae,0xb1,0xb4,0xb7,0xba,0xbc,0xbf,0xc2,0xc5 
,0xc7,0xca,0xCC,0xcf,0xd1,0xd4,0xd6,0xd8,0xda,0xdd,0xdf,0xe1,0xe3,0xe5,0xe7,0xe9,0xea,0xec,0xee,0xef,0xf1,0xf2,0xf4,0xf5 
,0xf6,0xf7,0xf8,0xf9,0xfa,0xfb,0xfc,0xfd,0xfd,0xfe,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xfe,0xfd 
,0xfd,0xfc,0xfb,0xfa,0xf9,0xf8,0xf7,0xf6,0xf5,0xf4,0xf2,0xf1,0xef,0xee,0xec,0xea,0xe9,0xe7,0xe5,0xe3,0xe1,0xde,0xdd,0xda 
,0xd8,0xd6,0xd4,0xd1,0xcf,0xcc,0xca,0xc7,0xc5,0xc2,0xbf,0xbc,0xba,0xb7,0xb4,0xb1,0xae,0xab,0xa8,0xa5,0xa2,0x9f,0x9c,0x99 
,0x96,0x93,0x90,0x8d,0x89,0x86,0x83,0x80,0x80,0x7c,0x79,0x76,0x72,0x6f,0x6c,0x69,0x66,0x63,0x60,0x5d,0x5a,0x57,0x55,0x51 
,0x4e,0x4c,0x48,0x45,0x43,0x40,0x3d,0x3a,0x38,0x35,0x33,0x30,0x2e,0x2b,0x29,0x27,0x25,0x22,0x20,0x1e,0x1c,0x1a,0x18,0x16 
,0x15,0x13,0x11,0x10,0x0e,0x0d,0x0b,0x0a,0x09,0x08,0x07,0x06,0x05,0x04,0x03,0x02,0x02,0x01,0x00,0x00,0x00,0x00,0x00,0x00 
,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x02 ,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0d,0x0e,0x10,0x11,0x13,0x15 
,0x16,0x18,0x1a,0x1c,0x1e,0x20,0x22,0x25,0x27,0x29,0x2b,0x2e,0x30,0x33,0x35,0x38,0x3a,0x3d,0x40,0x43,0x45,0x48,0x4c,0x4e 
,0x51,0x55,0x57,0x5a,0x5d,0x60,0x63,0x66 ,0x69,0x6c,0x6f,0x72,0x76,0x79,0x7c,0x80 }; 
void delayms(uint t) 
{ 
    uint i; 
    while(t--) 
    { 
       for (i=0;i<125;i++);//對于11.0592M時鐘，約延時1ms 
    } 
} 
void delay(uint t) 
{ 
    uint i; 
    for (i=t;i>0;i--); 
} 

void time0_init() 
{ 
    TMOD|=0x01;   //定時器設置 16位 
    TH0=-50000/256; 
    TL0=-50000%256;//初始化值 
    ET0=1; 
    TR0=1; 
    EA=1; 
} 
void time0_int(void) interrupt 1 
{  
    TR0=0;//關閉定時器 
    TH0=-50000/256; 
    TL0=-50000%256;//重裝初值 
if(S0==0) 
{ 
     delayms(10);//按鍵消抖 
     if(S0==0) m++; 
   while(!S0);//松手檢測 
} 

if(S1==0) 
{ 
     delayms(10); 
     if(S1==0) x=x+1; 
   while(!S1);//松手檢測 
} 

if(S2==0) 
{ 
     delayms(10); 
     if(S2==0) x=x-1; 
   while(!S2);//松手檢測 
} 

if(S3==0) 
{ 
     delayms(10); 
     if(S3==0) y=y+5; 
   while(!S3);//松手檢測 
} 

if(y>254) y=0; 
if(m>5) m=0; 
if(x>50) x=0; 
TR0=1;//啟動定時器 
} 
void fangbo()    //方波 
{  
   uchar i,j; 
   j=255-y; 
   CS_DA=0; 
   WR_DA=0; 
for(i=y;i>0;i--) 
{ 
    P0=0; 
    delay(x); 
} 
while(j--) 
{ 
    P0=255; 
    delay(x); 
}    
} 
void juchi()    //鋸齒波 
{ 
    uchar i; 
    CS_DA=0; 
    WR_DA=0; 
for(i=255;i>0;i--) 
{    
     P0=i; 
     delay(x); 
} 
} 
void sanjiao()      //三角波 
{ 
uchar i; 
    CS_DA=0; 
    WR_DA=0; 
for(i=0;i<255;i++) 
{ 
     P0=i; 
     delay(x); 
} 
while(i--) 
{ 
    P0=i; 
    delay(x); 
} 
} 
void tixing()         //梯形波 
{ 
uchar i=255,j,k; 
CS_DA=0; 
WR_DA=0; 
while(i--) 
{ 
   P0=i; 
   delay(x); 
} 
for(j=0;j<100;j++) 
{ 
   P0=0; 
   delay(x); 
} 
for(k=0;k<255;k++) 
{ 
   P0=k; 
   delay(x); 
} 
} 
void sin()      //正弦波 
{  
uchar a;  
CS_DA=0; 
WR_DA=0; 
for(a=0;a<255;a++) 
{ 
   P0=SinTab[a]; 
   delay(x); 
} 
} 
main() 
{ 
time0_init(); 
while(1) 
{ 
   switch(m) 
   { 
     case 0: 
     fangbo();    //方波 
     break; 
     case 1: 
     juchi();    //鋸齒波 
     break; 
     case 2: 
     sanjiao();   //三角波 
     break; 
     case 3: 
     sin();    //正弦波 
     break; 
     case 4: 
     tixing();    //梯形波 
     break; 
     default: fangbo(); 
   } 
} 
}