pwm.c

51单片机方波发生器

//单片机产生方波、锯齿波、三角波程序

#include<reg51.h> 

#define uchar unsigned char 
#define uint unsigned int 

unsigned char x=0,m=0,y=50; 

sbit WR_DA=P2^1; 
sbit CS_DA=P2^0;//DA与单片机的接口 
sbit S0=P3^2; //波形选择，每次按下将产生不同的波形 
sbit S1=P3^3; //频率减 
sbit S2=P3^4; //频率加 
sbit S3=P3^5; //调节方波的占空比 
sbit led=P2^2; //调节方波的占空比 
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++);//对于11.0592M时钟，约延时1ms 
    } 
} 

void delay(uint t) 
{ 
    uint i; 
    for (i=t;i>0;i--); 
} 


void time0_init() 
{ 
    TMOD|=0x01;   //定时器设置 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;//关闭定时器 
    TH0=-50000/256; 
    TL0=-50000%256;//重装初值 

if(S0==0) 
{ 
     delayms(10);//按键消抖 
     if(S0==0)
	  {
	  m++; 
	    if(m==5)
		    m=0;
	    led=0;
	  }
   while(!S0);//松手检测 
} 

if(S1==0) 
{ 
     delayms(10); 
     if(S1==0)
	  {
	  x=x+1; 
	  led=1;
	  }
   while(!S1);//松手检测 
} 

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

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

if(y>254) y=0; 
if(m>5) m=0; 
if(x>50) x=0; 
TR0=1;//启动定时器 
} 

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()    //锯齿波 
{ 
    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();    //锯齿波 
     break; 
     case 2: 
     sanjiao();   //三角波 
     break; 
     case 3: 
     sin();    //正弦波 
     break; 
     case 4: 
     tixing();    //梯形波 
     break; 
     default: fangbo(); 
   } 
} 
} 



//参考链接：http://www.picavr.com/news/2010-08/2297.htm