1、设计需求
信号发生器是在生产和科技领域中都有着广泛应用的一种信号源 。现利用单片机 的优越特性制作一种体积小，使用方便的低频信号发生器 。以AT89C51单片机为核心结合低速D/A，通过设计与编程实现了锯齿波、方波、正 弦波的产生及其自由切换以及实现频率、相位的可调与多相波的同时输出。
2、设计思路及方案
本实验采用AT89C51单片机构造低频信号发生器，可产生正弦波，方波，三角波，锯齿波四种波形，通过C语言对单片机的编程即可产生相应的波形信号，并可以通过键盘进行各种功能的转换和信号频率的控制，当输出的数字信号通过DAC0832（直通式）数模转换成模拟信号也就得到所需要的信号波形，通过运算放大器的放大输出波形，同时让液晶显示输出的波形信息。硬件原理图：
3、程序主函数
#include <reg51.h>
#include<string.h>
#define uchar unsigned char
#define uint unsigned int
sbit RS=P3^0;
sbit RW=P3^1;
sbit EN=P3^3;
sbit K1=P2^0;
sbit K2=P2^1;
sbit K3=P2^2;
sbit K4=P2^3;
sbit K5=P2^4;
uchar WaveChoice=1;
uchar ys=30;
uchar i,a=0;
uchar sqar_num=128;
uint freq;
uchar code Sin[]={"Sine "};
uchar code Squ[]={"Square "} ;
uchar code Tri[]={"Triangle "};
uchar code Saw[]={"Sawtooth "} ;
uchar code No[]={"No Signal out "};
uchar code Wave[]={"Wave :"};
uchar code Fre[]={"Freq :"};
uchar code tosin[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(uchar ms)
{
uchar i;
while(ms--) for(i=0;i<120;i++);
}
void Delay1(uint y)
{
uint i;
for(i=y;i>0;i--);
}
uchar Busy_Check()
{
uchar LCD_Status;
RS=0; // 寄存器选择
RW=1; //读状态寄存器
EN=1; // 开始读
DelayMS(1);
LCD_Status=P1;
EN=0;
return LCD_Status;
}
void Write_LCD_Command(uchar cmd)
{
while((Busy_Check()&0x80)==0x80); //忙等待
RS=0; //选择命令寄存器
RW=0; //写
EN=0;
P1=cmd;EN=1;DelayMS(1);EN=0;
}
void Write_LCD_Data(uchar dat)
{
while((Busy_Check()&0x80)==0x80); //忙等待
RS=1; RW=0; EN=0; P1=dat;EN=1;DelayMS(1);EN=0;
}
void Init_LCD()
{
Write_LCD_Command(0x38);
DelayMS(1);
Write_LCD_Command(0x01); //清屏
DelayMS(1);
Write_LCD_Command(0x06); //字符进入模式：屏幕不动，字符后移
DelayMS(1);
Write_LCD_Command(0x0C); //显示开、关光标
DelayMS(1);
}
void Write_freq(uint k)
{
uchar qian,bai,shi,ge;
qian=k/1000;
bai=k/100%10;
shi=k/10%10;
ge=k%10;
Write_LCD_Command(0x86+0x40);
Write_LCD_Data(0x30+qian);
Write_LCD_Data(0x30+bai);
Write_LCD_Data(0x30+shi);
Write_LCD_Data(0x30+ge);
Write_LCD_Data(0x48);
Write_LCD_Data(0x5a);
}
void Xianshi_f()
{
if(WaveChoice==1)
{
freq=(10000000/(50000+2860*ys));
Write_freq(freq);
}
if(WaveChoice==2)
{
freq=(10000000/(50000+2300*ys));
Write_freq(freq);
}
if(WaveChoice==3)
{
freq=(10000000/(14000+2300*ys));
Write_freq(freq);
}
if(WaveChoice==4)
{
freq=(10000000/(15000+2300*ys));
Write_freq(freq);
}
}
void Write_wave(uchar t )
{
switch(t)
{
case 0:
Write_LCD_Command(0x86);
DelayMS(5);
for (i=0;i<sizeof(No)-1;i++)
{
Write_LCD_Data(No[i]);
DelayMS(5);
}
break;
case 1:
ys=25;
Write_LCD_Command(0x86);
DelayMS(5);
for (i=0;i<sizeof(Sin)-1;i++)
{
Write_LCD_Data(Sin[i]);
DelayMS(5);
}
break;
case 2:
ys=30;
Write_LCD_Command(0x86);
DelayMS(5);
for (i=0;i<sizeof(Squ)-1;i++)
{
Write_LCD_Data(Squ[i]);
DelayMS(5);
}
break;
case 3:
ys=30;
Write_LCD_Command(0x86);
DelayMS(5);
for (i=0;i<sizeof(Tri)-1;i++)
{
Write_LCD_Data(Tri[i]);
DelayMS(5);
}
break;
case 4:
ys=30;
Write_LCD_Command(0x86);//液晶显示位置
DelayMS(5);
for (i=0;i<sizeof(Saw)-1;i++)
{
Write_LCD_Data(Saw[i]);
DelayMS(5);
}
break;
}
}
void Out_Wave(uchar i)
{ uchar j;
switch(i)
{
case 0: P0=0x00;break;
case 1:
for (j=0;j<255;j++)
{
P0=tosin[j];
Delay1(ys);
}
break;
case 2:
{
if(a<sqar_num)
{
P0=0xff;
Delay1(ys);
}
else
{
P0=0x00;
Delay1(ys);
}
a++;
} break;
case 3:
{
if(a<128)
{
P0=a;
Delay1(ys);
}
else
{
P0=255-a;
Delay1(ys);
}
a++;
} break;
case 4:
{
if(a<255)
{
P0=a;
Delay1(ys);
}
a++;
if(a==255)
{
a=0;
} break;
}
}
}
void keyscanf()
{
if(K2==0)
{
DelayMS(5);
if(K2==0)
{
while(!K2);
ys--;
if(ys==0)
ys=20;
}
}
if(K3==0)
{
DelayMS(5);
if(K3==0)
{
while(!K3);
ys++;
if(ys>22)
ys=20;
}
}
if(K4==0)
{
DelayMS(5);
if(K4==0)
{
while(!K4);
if(WaveChoice==2)
sqar_num=sqar_num+2;
if(sqar_num==238)
sqar_num=128;
}
}
if(K5==0)
{
DelayMS(5);
if(K5==0)
{
while(!K5);
if(WaveChoice==2)
sqar_num=sqar_num-2;
if(sqar_num==18)
sqar_num=128;
}
}
}
void main()
{
Init_LCD();
IE=0X81;
IT0=1;
Write_LCD_Command(0x80);//--显示wave:
DelayMS(5);
for (i=0;i<sizeof(Wave)-1;i++)
{
Write_LCD_Data(Wave[i]);
DelayMS(5);
}
Write_LCD_Command(0x80+0X40);//----显示freq:
DelayMS(5);
for (i=0;i<sizeof(Fre)-1;i++)
{
Write_LCD_Data(Fre[i]);
DelayMS(5);
}
Write_wave(WaveChoice);
while (1)
{
keyscanf();
Out_Wave(WaveChoice);
if(!(K1&K2&K3))
Xianshi_f();
}
}
void EX_INT0() interrupt 0
{
WaveChoice++;
if(WaveChoice==5) WaveChoice=1;
Write_wave(WaveChoice);
}完整资料：
https://market.m.taobao.com/app/idleFish-F2e/widle-taobao-rax/page-detail?wh_weex=true&wx_navbar_transparent=true&id=614264597552&ut_sk=1.WUpxx7gpwUoDAMmnnrBIzAno_12431167_1585212293567.Copy.detail.614264597552.1828622527&forceFlush=1
