本文介紹波形發生器非實物， 乃是模擬。
功能簡介：利用89C51單片機和數模轉換器件DAC0832產生所需不同信號的低頻信號源， 其信號幅度和頻率都是可以按要求控制的。 設計思路：採用標準 AT89C51單片機作為控制器；波形選擇通過按鍵來選擇， 波形通過DAC0832。 單片機作為資料處理及控制核心， 由單片機完成人機界面、系統控制、信號的採集分析以及信號的處理和變換， 採用按鍵輸入， 利用虛擬示波器顯示波形的方案。 D/A轉換器簡介：DAC0832是雙列直插式8位D/A轉換器。 能完成數位量輸入到類比量(電流)輸出的轉換。 其主要參數如下：解析度為8位，
運算放大電路（放大圖）：
波形產生原理及模組設計
波形產生的原理：
1、記憶體中首先存儲波形的數位量值陣列TABLE；
2、51單片機讀取陣列中的值， 送入D/A轉換器；
3、D/A轉換器將輸入的數位值轉換成類比量輸出；
4、D/A輸出的模擬電流量通過運放轉換成電壓量輸出。
由單片機採用程式設計方法產生四種波形、通過DA轉換模組DAC0832在進過濾波放大之後輸出。
按一下模擬介面左下方的開始按扭， 模擬就開始了。 具體模擬過程如下：
（1）f=50HZ正弦波的調試結果
（2）f=50HZ方波的調試結果
（3）f=50HZ三角波的調試結果
#include
#define uchar unsigned char
#define uint unsigned int
#define DAdata P0//DA數據埠
sbit DA_S1= P2^0; // 控制DAC0832的8位輸入寄存器， 僅當都為0時， 可以輸出資料(處於直通狀態)， 否則， 輸出將被鎖存
sbit DA_S2= P2^1; // 控制DAC0832的8位DAC寄存器， 僅當都為0時， 可以輸出資料(處於直通狀態)， 否則，輸出將被鎖存
sbit key= P3^2;
uchar wavecount; //'抽點'計數
uchar THtemp,TLtemp;//傳遞頻率的中間變數
uchar judge=1; //在方波輸出函數中用於簡單判別作用
uchar waveform; //當其為0、1、2時，分別代表三種波
uchar code freq_unit[3]={10,50,200}; //三種波的頻率單位
uchar idata wavefreq[3]={1,1,1}; //給每種波定義一個陣列單元，用於存放單位頻率的個數
uchar code lcd_hang1[]={"Sine Wave " "Triangle Wave " "Square Wave " "Select Wave: " "press No.1 key! "};
uchar idata lcd_hang2[16]={"f= Hz "};
uchar code waveTH[]={
0xfd,0xfe,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
0xfd,0xfe,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
0xec,0xf6,0xf9,0xfb,0xfc,0xfc,0xfd,0xfd,0xfd,0xfe};
uchar code waveTL[]={
0x06,0x8a,0x10,0x4e,0x78,0x93,0xa8,0xb3,0xbe,0xc6, //正弦波頻率調整中間值
0xac,0xde,0x48,0x7a,0x99,0xaf,0xbb,0xc8,0xd0,0xde,//三角波頻率調整中間值
0x88,0x50,0x90,0x32,0x34,0xbe,0x4a,0xa3,0xe5,0x2c};
/*************************************************************************************************/
uchar code triangle_tab[]={ //每隔數字8，採取一次
0x00,0x08,0x10,0x18,0x20,0x28,0x30,0x38,0x40,0x48,0x50,0x58,0x60,0x68,0x70,0x78,
0x80,0x88,0x90,0x98,0xa0,0xa8,0xb0,0xb8,0xc0,0xc8,0xd0,0xd8,0xe0,0xe8,0xf0,0xf8,0xff,
0xf8,0xf0,0xe8,0xe0,0xd8,0xd0,0xc8,0xc0,0xb8,0xb0,0xa8,0xa0,0x98,0x90,0x88,0x80,
0x78,0x70,0x68,0x60,0x58,0x50,0x48,0x40,0x38,0x30,0x28,0x20,0x18,0x10,0x08,0x00};
uchar code sine_tab[256]={
//輸出電壓從0到最大值（正弦波1/4部分）
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,
//輸出電壓從最大值到0（正弦波1/4部分）
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,
//輸出電壓從0到最小值（正弦波1/4部分）
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,
//輸出電壓從最小值到0（正弦波1/4部分）
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 delay(uchar z)
{
uint x,y;
for(x=z;x>0;x--)
for(y=110;y>0;y--);
}
void triangle_out()//三角波輸出
{
DAdata=triangle_tab[wavecount++];
if(wavecount>64) wavecount=0;
DA_S1=0; //打開8位輸入寄存器
DA_S1=1; //關閉8位輸入寄存器
}
void sine_out() //正弦波輸出
{
DAdata=sine_tab[wavecount++];
DA_S1=0; //打開8位輸入寄存器
DA_S1=1; //關閉8位輸入寄存器
}
void square_out() //方波輸出
{
judge=~judge;
if(judge==1) DAdata=0xff;
else DAdata=0x00;
DA_S1=0; //打開8位輸入寄存器
DA_S1=1; //關閉8位輸入寄存器
}
/************1602液晶的相關函數*************/
#define lcd_ports P1
sbit rs=P2^2;
sbit rw=P2^3;
sbit lcden=P2^4;
void write_com(uchar com)
{
rs=0;//置零，表示寫指令
lcden=0;
lcd_ports=com;
delay(5);
lcden=1;
delay(5);
lcden=0;
}
void write_date(uchar date)
{
rs=1;//置1，表示寫資料（在指令所指的地方寫資料）
lcden=0;
lcd_ports=date;
delay(5);
lcden=1;
delay(5);
lcden=0;
}
void disp_lcd(uchar addr,uchar *temp1)
{
uchar num;
write_com(addr);
delay(1); //延時一會兒???
for(num=0;num
{
write_date(temp1[num]);//或者這樣寫write_date(*(temp1+num));
delay(1);
}
}
void init_lcd()
{
//uchar num;
lcden=0; //可有可無???
rw=0; //初始化一定要設置為零，表示寫資料
write_com(0x38); //使液晶顯示點陣，為下面做準備
write_com(0x0c); //初始設置
write_com(0x06); //初始設置
write_com(0x01); //清零
write_com(0x80); //使指標指向第一行第一格
disp_lcd(0x80,&lcd_hang1[3*16]); //在第一行顯示
disp_lcd(0xc0,&lcd_hang1[4*16]); //在第二行顯示
}
/********************1602液晶函式宣告結束*********************/
void main()
{
uchar i=0;
DA_S2=0; //使DAC寄存器處於直通狀態
DAdata=0;
DA_S1=1; //關閉8位輸入寄存器
init_lcd();
waveform=0;
TMOD=0x01; //設置計時器0為16位元工作方式
IT0=1; //設置外部中斷0為下降沿觸發
ET0=1; //開計時器中斷
EX0=1;
EA=1;
while(1)
{
//DAout(0xff); //可輸出TTL波形
//DAout(0x80);
//T_temp=32;
}
}
void timer0() interrupt 1
{
TH0=THtemp;
TL0=TLtemp;
if(waveform==0) sine_out();
else if(waveform==1) triangle_out();
else if(waveform==2) square_out();
}
void key_int0() interrupt 0
{
uchar keytemp;
uint total_freq; //總頻率
EA=0; TR0=0; //關總中斷與計時器
delay(5); //延時夠嗎???
if(key==0) //確實有按鍵按下而引發中斷
{
keytemp=P3&0xf0; //獲取P3口高四位的值
switch(keytemp)
{
case 0xe0://選擇波形
waveform++;
if(waveform>2) waveform=0;
break;
case 0xd0: //頻率按規定單位依次增加
wavefreq[waveform]++;
if(wavefreq[waveform]>10) wavefreq[waveform]=1; // /*這邊要用“>10”，因為它比“=11”可靠
break; // 性更高,使加數有個上限，不會一直加下去*/
case 0xb0: //頻率按規定單位依次衰減
wavefreq[waveform]--;
if(wavefreq[waveform]
break;
case 0x70: //TTL輸出
DA_S2=1; //使DAC寄存器關閉
break;
}
THtemp=waveTH[waveform*10+(wavefreq[waveform]-1)]; //方括號中選取第幾個數後，並把該值賦給T_temp
TLtemp=waveTL[waveform*10+(wavefreq[waveform]-1)];
total_freq= wavefreq[waveform] * freq_unit[waveform]; //求輸出頻率（個數*單位）
lcd_hang2[5]=total_freq%10+0x30; //在液晶中顯示個位，(0x30 在液晶顯示中表示數位0)
total_freq/=10; lcd_hang2[4]=total_freq%10+0x30; //在液晶中顯示時十位元
total_freq/=10; lcd_hang2[3]=total_freq%10+0x30; //在液晶中顯示時百位元
total_freq/=10; lcd_hang2[2]=total_freq%10+0x30; //在液晶中顯示時千位元
disp_lcd(0x80,&lcd_hang1[waveform*16]); //在第一行顯示
disp_lcd(0xc0,lcd_hang2); //在第二行顯示
}
wavecount=0; //'抽點'計數清零
while(!key);
EA=1; TR0=1; //開啟總中斷與計時器
}
否則，輸出將被鎖存sbit key= P3^2;
uchar wavecount; //'抽點'計數
uchar THtemp,TLtemp;//傳遞頻率的中間變數
uchar judge=1; //在方波輸出函數中用於簡單判別作用
uchar waveform; //當其為0、1、2時，分別代表三種波
uchar code freq_unit[3]={10,50,200}; //三種波的頻率單位
uchar idata wavefreq[3]={1,1,1}; //給每種波定義一個陣列單元，用於存放單位頻率的個數
uchar code lcd_hang1[]={"Sine Wave " "Triangle Wave " "Square Wave " "Select Wave: " "press No.1 key! "};
uchar idata lcd_hang2[16]={"f= Hz "};
uchar code waveTH[]={
0xfd,0xfe,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
0xfd,0xfe,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
0xec,0xf6,0xf9,0xfb,0xfc,0xfc,0xfd,0xfd,0xfd,0xfe};
uchar code waveTL[]={
0x06,0x8a,0x10,0x4e,0x78,0x93,0xa8,0xb3,0xbe,0xc6, //正弦波頻率調整中間值
0xac,0xde,0x48,0x7a,0x99,0xaf,0xbb,0xc8,0xd0,0xde,//三角波頻率調整中間值
0x88,0x50,0x90,0x32,0x34,0xbe,0x4a,0xa3,0xe5,0x2c};
/*************************************************************************************************/
uchar code triangle_tab[]={ //每隔數字8，採取一次
0x00,0x08,0x10,0x18,0x20,0x28,0x30,0x38,0x40,0x48,0x50,0x58,0x60,0x68,0x70,0x78,
0x80,0x88,0x90,0x98,0xa0,0xa8,0xb0,0xb8,0xc0,0xc8,0xd0,0xd8,0xe0,0xe8,0xf0,0xf8,0xff,
0xf8,0xf0,0xe8,0xe0,0xd8,0xd0,0xc8,0xc0,0xb8,0xb0,0xa8,0xa0,0x98,0x90,0x88,0x80,
0x78,0x70,0x68,0x60,0x58,0x50,0x48,0x40,0x38,0x30,0x28,0x20,0x18,0x10,0x08,0x00};
uchar code sine_tab[256]={
//輸出電壓從0到最大值（正弦波1/4部分）
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,
//輸出電壓從最大值到0（正弦波1/4部分）
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,
//輸出電壓從0到最小值（正弦波1/4部分）
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,
//輸出電壓從最小值到0（正弦波1/4部分）
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 delay(uchar z)
{
uint x,y;
for(x=z;x>0;x--)
for(y=110;y>0;y--);
}
void triangle_out()//三角波輸出
{
DAdata=triangle_tab[wavecount++];
if(wavecount>64) wavecount=0;
DA_S1=0; //打開8位輸入寄存器
DA_S1=1; //關閉8位輸入寄存器
}
void sine_out() //正弦波輸出
{
DAdata=sine_tab[wavecount++];
DA_S1=0; //打開8位輸入寄存器
DA_S1=1; //關閉8位輸入寄存器
}
void square_out() //方波輸出
{
judge=~judge;
if(judge==1) DAdata=0xff;
else DAdata=0x00;
DA_S1=0; //打開8位輸入寄存器
DA_S1=1; //關閉8位輸入寄存器
}
/************1602液晶的相關函數*************/
#define lcd_ports P1
sbit rs=P2^2;
sbit rw=P2^3;
sbit lcden=P2^4;
void write_com(uchar com)
{
rs=0;//置零，表示寫指令
lcden=0;
lcd_ports=com;
delay(5);
lcden=1;
delay(5);
lcden=0;
}
void write_date(uchar date)
{
rs=1;//置1，表示寫資料（在指令所指的地方寫資料）
lcden=0;
lcd_ports=date;
delay(5);
lcden=1;
delay(5);
lcden=0;
}
void disp_lcd(uchar addr,uchar *temp1)
{
uchar num;
write_com(addr);
delay(1); //延時一會兒???
for(num=0;num
{
write_date(temp1[num]);//或者這樣寫write_date(*(temp1+num));
delay(1);
}
}
void init_lcd()
{
//uchar num;
lcden=0; //可有可無???
rw=0; //初始化一定要設置為零，表示寫資料
write_com(0x38); //使液晶顯示點陣，為下面做準備
write_com(0x0c); //初始設置
write_com(0x06); //初始設置
write_com(0x01); //清零
write_com(0x80); //使指標指向第一行第一格
disp_lcd(0x80,&lcd_hang1[3*16]); //在第一行顯示
disp_lcd(0xc0,&lcd_hang1[4*16]); //在第二行顯示
}
/********************1602液晶函式宣告結束*********************/
void main()
{
uchar i=0;
DA_S2=0; //使DAC寄存器處於直通狀態
DAdata=0;
DA_S1=1; //關閉8位輸入寄存器
init_lcd();
waveform=0;
TMOD=0x01; //設置計時器0為16位元工作方式
IT0=1; //設置外部中斷0為下降沿觸發
ET0=1; //開計時器中斷
EX0=1;
EA=1;
while(1)
{
//DAout(0xff); //可輸出TTL波形
//DAout(0x80);
//T_temp=32;
}
}
void timer0() interrupt 1
{
TH0=THtemp;
TL0=TLtemp;
if(waveform==0) sine_out();
else if(waveform==1) triangle_out();
else if(waveform==2) square_out();
}
void key_int0() interrupt 0
{
uchar keytemp;
uint total_freq; //總頻率
EA=0; TR0=0; //關總中斷與計時器
delay(5); //延時夠嗎???
if(key==0) //確實有按鍵按下而引發中斷
{
keytemp=P3&0xf0; //獲取P3口高四位的值
switch(keytemp)
{
case 0xe0://選擇波形
waveform++;
if(waveform>2) waveform=0;
break;
case 0xd0: //頻率按規定單位依次增加
wavefreq[waveform]++;
if(wavefreq[waveform]>10) wavefreq[waveform]=1; // /*這邊要用“>10”，因為它比“=11”可靠
break; // 性更高,使加數有個上限，不會一直加下去*/
case 0xb0: //頻率按規定單位依次衰減
wavefreq[waveform]--;
if(wavefreq[waveform]
break;
case 0x70: //TTL輸出
DA_S2=1; //使DAC寄存器關閉
break;
}
THtemp=waveTH[waveform*10+(wavefreq[waveform]-1)]; //方括號中選取第幾個數後，並把該值賦給T_temp
TLtemp=waveTL[waveform*10+(wavefreq[waveform]-1)];
total_freq= wavefreq[waveform] * freq_unit[waveform]; //求輸出頻率（個數*單位）
lcd_hang2[5]=total_freq%10+0x30; //在液晶中顯示個位，(0x30 在液晶顯示中表示數位0)
total_freq/=10; lcd_hang2[4]=total_freq%10+0x30; //在液晶中顯示時十位元
total_freq/=10; lcd_hang2[3]=total_freq%10+0x30; //在液晶中顯示時百位元
total_freq/=10; lcd_hang2[2]=total_freq%10+0x30; //在液晶中顯示時千位元
disp_lcd(0x80,&lcd_hang1[waveform*16]); //在第一行顯示
disp_lcd(0xc0,lcd_hang2); //在第二行顯示
}
wavecount=0; //'抽點'計數清零
while(!key);
EA=1; TR0=1; //開啟總中斷與計時器
}