原理说明
一、电源电路
输入使用12V直流,直接给DAC0832数模转换器和LM358运放供电。然后经过7805稳压器稳压输出5V,给单片机系统,1602液晶部分供电。
二、 单片机最小系统部分
单片机最小系统部分,复位电路,电容C1实现上电自动复位。独立按键部分,实现频率加减调节,波形选择,步进值调节。U2为10K排阻,给单片机P0口提供上拉电阻。Y1为12MHz晶振,给单片机提供时钟。
三、1602液晶显示模块电路
1602液晶模块电路使用8位并口进行控制。
四、 数模转换电路
单片机P2口输出数字信号给DAC0832,DAC0832配合LM358运放,把P2口数字量转换成模拟量输出。
其中电位器R9用于调节波形幅值。幅值最大值为5V。
五、 波形产生原理
单片机P2口输出按正弦等波形规律变化的数字量,例,正弦波一个周期取64个点。则单片机一次输出64个按正弦规律变化的数字量,经DA转换后就输出了按正弦规律变化的模拟量。即产生了正弦波。其他波形原理一样。
频率控制:单片机控制数字信号输出的快慢,可以控制波形频率。控制中,单片机采用定时器定时一个时间t,时间t到达后产生定时器溢出中断,中断里单片机控制输出一个数字量。64个中断后,即输出64个数字量,就输出了一个波形完整的周期。由于单片机速度有限,12M晶振,指令周期是1us。例如t=5us,则波形一个周期是5*64=320uS,则波形周期是3.125KHZ。
单片机通过设置定时器时间t来控制波形输出的频率。
更过内容,可参考网上其他文档说明:
https://wenku.baidu.com/view/b5deb046be1e650e52ea99e6.html
仿真原理图如下(proteus仿真工程文件可到本帖附件中下载)
单片机源程序如下:
- #include<reg52.h> //包含头文件
- #include<intrins.h>
- #define uchar unsigned char //宏定义
- #define uint unsigned int
- sbit s1=P1^0; //定义按键的接口
- sbit s2=P1^1;
- sbit s3=P1^2;
- sbit s4=P1^3;
-
- sbit lcdrs=P1^6; //液晶控制位
- sbit lcden=P1^7;
- char num,boxing,u; //定义全局变量
- int pinlv=50,bujin=10,bujin1=10;
- uchar geshu=1; //两次DA输出数组中的个数
- uchar code table[]="0123456789"; //定义显示的数组
- uchar code table1[]="pinlv:boxing:";
- unsigned long int m;
- int n=0;
- float hc=0;
- int a,b,h,num1;
- uchar code sin[64]={
- 135,145,158,167,176,188,199,209,218,226,234,240,245,249,252,254,254,253,251,247,243,237,230,222,213,204,193,182,170,158,
- 146,133,121,108,96,84,72,61,50,41,32,24,17,11,7,3,1,0,0,2,5,9,14,20,28,36,45,55,66,78,90,102,114,128
- }; //正弦波取码
- uchar code juxing[64]={
- 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
- 255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
- }; //矩形波取码
- uchar code juchi[64]={
- 0,4,8,12,16,20,24,28,32,36,40,45,49,53,57,61,65,69,73,77,81,85,89,93,97,101,105,109,113,117,121,125,130,134,138,142,
- 146,150,154,158,162,166,170,174,178,182,186,190,194,198,202,206,210,215,219,223,227,231,235,239,243,247,251,255
- }; //锯齿波取码
- uchar code sanjiao[64]={
- 0,8,16,24,32,40,48,56,64,72,80,88,96,104,112,120,128,136,144,152,160,168,176,184,192,200,208,216,224,232,240,248,
- 248,240,232,224,216,208,200,192,184,176,168,160,152,144,136,128,120,112,104,96,88,80,72,64,56,48,40,32,24,16,8,0
- }; //三角波取码
- void delay(uint xms) //延时函数
- {
- int a,b;
- for(a=xms;a>0;a--)
- for(b=110;b>0;b--);
- }
- void write_com(uchar com) //写命令函数
- {
- lcdrs=0;
- P0=com;
- delay(1);
- lcden=1;
- delay(1);
- lcden=0;
- }
- void write_date(uchar date) //写数据函数
- {
- lcdrs=1;
- P0=date;
- delay(1);
- lcden=1;
- delay(1);
- lcden=0;
- }
- void init_lcd() //初始化函数
- {
- lcden=0; //默认开始状态为关使能端,见时序图
- write_com(0x0f);
- write_com(0x38); //显示模式设置,默认为0x38,不用变。
- write_com(0x01); //显示清屏,将上次的内容清除,默认为0x01.
- write_com(0x0c); //显示功能设置0x0f为开显示,显示光标,光标闪烁;0x0c为开显示,不显光标,光标不闪
- write_com(0x06); //设置光标状态默认0x06,为读一个字符光标加1.
- write_com(0x80); //设置初始化数据指针,是在读指令的操作里进行的
- }
- void initclock() //时钟初始化
- {
- uint i;
- TMOD=0x01;
- TH0=a;
- TL0=b;
- EA=1;
- ET0=1;
- TR0=1;
- for(i=6;i<13;i++) //显示初始化
- {
- write_date(table1[i]);
- delay(2);
- }
- write_com(0x80+0x40);
- for(i=0;i<6;i++)
- {
- write_date(table1[i]);
- delay(2);
- }
- write_com(0x80+7);
- write_date('s');
- write_date('i');
- write_date('n');
- write_date(' ');
- write_date(' ');
- write_date(' ');
- write_date(' ');
- write_com(0x80+0x40+0xa);
- write_date(' ');
- write_date('1');
- write_date('0');
- write_date('H');
- delay(2);
- write_date('Z');
- delay(2);
- }
- void display() //显示函数
- {
- uchar wan,qian,bai,shi,ge;
- uint a=0;
- a=pinlv;
- wan=a/10000;
- qian=a/1000%10;
- bai=a/100%10;
- shi=a%100/10;
- ge=a%100%10;
- write_com(0x80+0x40+8);
- write_date(table[wan]);
- delay(2);
- write_date(table[qian]);
- delay(2);
- write_date(table[bai]);
- delay(2);
-
- write_date(table[shi]);
- delay(2);
- write_date(table[ge]);
- delay(2);
- write_date('H');
- delay(2);
- write_date('Z');
- delay(2);
- if(boxing==0)
- {
- write_com(0x80+7);
- write_date('s');
- write_date('i');
- write_date('n');
- write_date(' ');
- write_date(' ');
- write_date(' ');
- write_date(' ');
- }
- if(boxing==1)
- {
- write_com(0x80+7);
- write_date('j');
- write_date('u');
- write_date('x');
- write_date('i');
- write_date('n');
- write_date('g');
- }
- if(boxing==2)
- {
- write_com(0x80+7);
- write_date('s');
- write_date('a');
- write_date('n');
- write_date('j');
- write_date('i');
- write_date('a');
- write_date('o');
- }
- if(boxing==3)
- {
- write_com(0x80+7);
- write_date('j');
- write_date('u');
- write_date('c');
- write_date('h');
- write_date('i');
- write_date(' ');
- write_date(' ');
- }
- }
- uchar keyscan() //键盘检测函数
- {
- // if(P1&0x0F==0x0F) return 0;
- if(s1==0)
- {
- EA=0;
- delay(1);
- if(s1==0)
- {
- while(!s1);
- pinlv+=bujin;
- if(pinlv>30000)
- {
- pinlv=30000;
- }
- geshu=pinlv/120+1;
- if(pinlv>960)
- {
- geshu=8;
- bujin=100;
- bujin1=100;
- }
- if(pinlv>1080) geshu=10;
- if(pinlv>2000) geshu=11;
- hc=15625/pinlv;
- m=hc*geshu;
- m-=54;
- m/=15;
-
- EA=1;
- display();
-
- }
- }
- if(s2==0)
- {
-
- delay(1);
- if(s2==0)
- {
- EA=0;
- while(!s2);
- pinlv-=bujin;
- if(pinlv<0)
- {
- pinlv=0;
- }
- geshu=pinlv/120+1;
- if(pinlv>960)
- {
- geshu=8;
- bujin=100;
- bujin1=100;
- }
- if(pinlv>1080) geshu=10;
- if(pinlv>2000) geshu=11;
- if(pinlv<=3100)
- {hc=15625/pinlv;
- m=hc*geshu;
- m-=54;
- m/=15;}
- else
- {
- m=65276+(pinlv-480);
- }
- display();
- EA=1;
- }
- }
- if(s3==0)
- {
- delay(1);
- if(s3==0)
- {
- EA=0;
- while(!s3);
- boxing++;
- if(boxing==4)
- {
- boxing=0;
- }
- display();
- EA=1;
- }
- }
- return 1;
- }
- void bujindisplay()
- {
- uint bai,shi,ge;
- bai=bujin1/100;
- shi=bujin1%100/10;
- ge=bujin1%100%10;
- write_com(0x80+6);
- write_date(table[bai]);
- delay(1);
- write_date(table[shi]);
- delay(1);
- write_date(table[ge]);
- delay(1);
- }
- void bujinjiance()
- {
- if(s4==0)
- {
- delay(3);
- if(s4==0)
- {
- while(!s4);
- h++;
- if(h==1)
- {
- write_com(0x01);
- write_com(0x80);
- write_date('b');delay(1);
- write_date('u');delay(1);
- write_date('j');delay(1);
- write_date('i');delay(1);
- write_date('n');delay(1);
- write_date(':');delay(1);
- bujin1=bujin;
-
- bujindisplay();
- }
- if(h==2)
- {
- h=0;
- bujin=bujin1;
-
- init_lcd();
- initclock();
- display();
- }
- }
- }
- if(h==1)
- {
- if(s1==0)
- {
- delay(5);
- if(s1==0)
- {
- while(!s1);
- bujin1++;
- if(bujin1==101)
- {
- bujin1=100;
- }
- bujindisplay();
- }
- }
- if(s2==0)
- {
- delay(5);
- if(s2==0)
- {
- while(!s2);
- bujin1--;
- if(bujin1==0)
- {
- bujin1=100;
- }
- bujindisplay();
- }
- }
- }
- }
- void main() //主函数
- {
-
- init_lcd();
- hc=15625/pinlv;
- m=hc*geshu;
- m-=54;
- m/=15;
- initclock();
- display();
- // csda=0;
- // wr=0;
- while(1)
- {
-
- switch(boxing)
- {
- case 0: P2=sin[u];
- break;
- case 1: P2=juxing[u];
- break;
- case 2: P2=sanjiao[u];
- break;
- case 3: P2=juchi[u];
- break;
- }
- u+=geshu;
- n=m;
- if(u>=64)
- {
- u=0;
- }
- while(n-->0);
- }
- }
- void T0_time()interrupt 1 //定时器
- {
-
- // TH0=a;
- // TL0=b;
- TH0=0;
- TL0=0;
- if(h==0)
- {
- keyscan();
- }
- bujinjiance();
-
-
- }
复制代码
Keil5代码与Proteus8.13仿真下载:
信号发生器.7z
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