基于51单片机的函数信号发生器
1、设计需求及目标
具体实现功能：
（1）由LCD1602液晶显示波形种类和频率值（频率范围10-100HZ）；
（2）可以通过按键设置波形种类和设定频率步进值；
（3）电位器可以改变振幅（0V-3.5V稳定）；
（4）可产生正弦波、锯齿波、三角波、矩形波；
（5）四个指示灯可分别指示发出的波形。
2、设计方案及思路
低频信号发生器系统主要由CPU、D/A转换电路、电流/电压转换电路、按键和波形指示电路、电源等电路组成。其工作原理为当分别按下切换按键就会分别出现方波、锯齿波、三角波、正弦波，并且有四个发光二极管分别作为不同的波形指示灯。液晶实时显示当前的输出频率和波形指示，输出的波形幅值可以通过电位器来微调。按键也可以调节输出频率的步进值。
3、硬件电路
4、部分代码
#include //包含头文件
#include
#define uchar unsigned char //宏定义
#define uint unsigned int
sbit s1=P3^5; //定义按键的接口
sbit s2=P3^6;
sbit s3=P3^7;
sbit s4=P3^4;
sbit led0=P3^0;
sbit led1=P3^1;
sbit led2=P3^2;
sbit led3=P3^3;
sbit lcdrs=P2^7; //液晶控制位
sbit lcden=P2^6;
char num,boxing,u; //定义全局变量
int pinlv=100,bujin=1,bujin1=1;
uchar code table[]="0123456789"; //定义显示的数组
uchar code table1[]="Fout= Wave form:";
unsigned long int m;
int a,b,h,num1;
//自定义字符
uchar code zifu[]={
0x0e,0x11,0x11,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x11,0x11,0x0e,0x00, //正弦波 0 1
0x00,0x07,0x04,0x04,0x04,0x04,0x1c,0x00,
0x00,0x1c,0x04,0x04,0x04,0x04,0x07,0x00, //矩形波 2 3
0x00,0x01,0x02,0x04,0x08,0x10,0x00,0x00,
0x00,0x10,0x08,0x04,0x02,0x01,0x00,0x00, //三角波 4 5
0x00,0x01,0x03,0x05,0x09,0x11,0x00,0x00, //锯齿波 6
};
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 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
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
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;
}
//自定义字符集
void Lcd_ram()
{
uint i,j,k=0,temp=0x40;
for(i=0;i<7;i++)
{
for(j=0;j<8;j++)
{
write_com(temp+j);
write_date(zifu[k]);
k++;
}
temp=temp+8;
}
}
void init_lcd() //初始化函数
{
uchar i;
lcden=0; //默认开始状态为关使能端，见时序图
Lcd_ram();
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
for(i=10;i<20;i++) //显示初始化
{
write_date(table1[i]);
}
write_com(0x80+0x40);
for(i=0;i<9;i++)
{
write_date(table1[i]);
}
write_com(0x80+10);
write_date(0);
write_date(1);
write_date(0);
write_date(1);
write_date(0);
write_date(1);
write_com(0x80+0x40+0x09);
write_date(' ');
write_date('1');
write_date('0');
write_date('.');
write_date('0');
write_date('H');
write_date('z');
}
void initclock() //时钟初始化
{
TMOD=0x01;
TH0=a;
TL0=b;
EA=1;
ET0=1;
TR0=1;
}
void display() //显示函数
{
uchar qian,bai,shi,ge;
qian=pinlv/1000;
bai=pinlv%1000/100;
shi=pinlv%1000%100/10;
ge=pinlv%1000%100%10;
write_com(0x80+0x40+0x09);
if(qian==0)
write_date(' ');
else
write_date(table[qian]);
if(qian==0&&bai==0)
write_date(' ');
else
write_date(table[bai]);
write_date(table[shi]);
write_date('.');
write_date(table[ge]);
write_date('H');
write_date('z');
if(boxing==0)
{
write_com(0x80+10);
write_date(0);
write_date(1);
write_date(0);
write_date(1);
write_date(0);
write_date(1);
led3=1;
led0=0;
}
if(boxing==1)
{
write_com(0x80+10);
write_date(2);
write_date(3);
write_date(2);
write_date(3);
write_date(2);
write_date(3);
led0=1;
led1=0;
}
if(boxing==2)
{
write_com(0x80+10);
write_date(4);
write_date(5);
write_date(4);
write_date(5);
write_date(4);
write_date(5);
led1=1;
led2=0;
}
if(boxing==3)
{
write_com(0x80+10);
write_date(6);
write_date(6);
write_date(6);
write_date(6);
write_date(6);
write_date(6);
led2=1;
led3=0;
}
}
void keyscan() //键盘检测函数
{
if(s1==0)
{
EA=0;
delay(2);
if(s1==0)
{
while(!s1);
pinlv+=bujin;
if(pinlv>1000)
{
pinlv=100;
}
display();
m=65536-(150000/pinlv);
a=m/256;
b=m%256;
EA=1;
}
}
if(s2==0)
{
delay(5);
if(s2==0)
{
EA=0;
while(!s2);
pinlv-=bujin;
if(pinlv<100)
{
pinlv=1000;
}
display();
m=65536-(150000/pinlv);
a=m/256;
b=m%256;
EA=1;
}
}
if(s3==0)
{
delay(5);
if(s3==0)
{
EA=0;
while(!s3);
boxing++;
if(boxing>=4)
{
boxing=0;
}
display();
EA=1;
}
}
}
void bujindisplay()
{
uint bai,shi,ge;
bai=bujin1/100;
shi=bujin1%100/10;
ge=bujin1%100%10;
write_com(0x80+11);
if(bai==0)
write_date(' ');
else
write_date(table[bai]);
write_date(table[shi]);
write_date('.');
write_date(table[ge]);
}
void bujinjiance()
{
if(s4==0)
{
delay(5);
if(s4==0)
{
while(!s4);
h++;
if(h==1)
{
write_com(0x01);
write_com(0x80);
write_date('S');delay(1); //step value
write_date('t');delay(1);
write_date('e');delay(1);
write_date('p');delay(1);
write_date(' ');delay(1);
write_date('v');delay(1);
write_date('a');delay(1);
write_date('l');delay(1);
write_date('u');delay(1);
write_date('e');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=1;
}
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();
m=65536-(150000/pinlv);
a=m/256;
b=m%256;
initclock();
led0=0;
while(1)
{
if(h==0)
{
keyscan();
// display();
}
bujinjiance();
switch(boxing)
{
case 0 : P1=sin[u]; break;
case 1 : P1=juxing[u]; break;
case 2 : P1=sanjiao[u]; break;
case 3 : P1=juchi[u]; break;
}
}
}
void T0_time()interrupt 1 //定时器
{
TH0=a;
TL0=b;
u++;
if(u>=64)
u=0;
}