用 单片机 产生方波、锯齿波、三角波、梯形波，频率可调

#include<reg51.h>
#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与 单片机 的接口
sbit S0=P3^0; //波形选择，每次按下将产生不同的波形
sbit S1=P3^1; //频率减
sbit S2=P3^2; //频率加
sbit S3=P3^3; //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++;
   while(!S0);//松手检测
}

if(S1==0)
{
     delayms(10);
     if(S1==0) x=x+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();
   }
}
}