【单片机基础】使用51单片机制作函数信号发生器（DAC0832使用仿真）

（1）DA转换

单片机作为一个数字电路系统，当需要采集外界模拟量的使用需要进行AD转换，将模拟量转换成数字量，供单片机使用。51单片机需要外部配置一个AD转换芯片来进行模拟量的采集，如我之前写了一篇ADC0832的使用。高级的单片机如STC12和STM32已经集成了AD转换功能，只需简单配置一下，便可以采集到AD转换后的数据。

AD转换（Analog to Digital）是模拟量转换数字量，那么DA转换（Digital to Analog）便是数字量转换成模拟量。

使用DAC0832进行数字到模拟的转换，再使用定时器控制输出波形的频率便可以制作一个函数信号发生器。

（2）DAC0832简介

CS：低电平有效，片选输入线
WR1：低电平大于500ms有效，输入锁存器
WR2：高电平有效，与XFER结合可将输入锁存器的8位数据传输到DAC寄存器中
XFER：低电平有效，数据传输控制输入线
DI0~DI7：8位数据位并行输入，有效时间大于90ns有效
VCC：电源输入5V-15V
VERF：基准电压输入线-10V~10V
RFB：反馈信号输入，可以看成一个反馈监测
IOUT1：电流输出1，其值随着输入线性变化
IOUT2：电流输出2，与OUT1值之和为一个常数

（3）电路设计

单片机最小系统

波形切换控制

（这里由于博主时间有限，例程代码的LED显示功能就没有写了）

（4）参考例程

#include 
#define uchar unsigned char
#define uint unsigned int

#define DI	P0											//8位数据输入线

//sbit sine_wave_LED1					= P1^0;	//正弦波指示灯
//sbit square_wave_LED2 			= P1^1;	//方波指示灯
//sbit triangular_wave_LED3 	= P1^2;	//三角波指示灯
//sbit sawtooth_wave_LED4			= P1^3;	//锯齿波指示灯
sbit change_wave_Key				= P1^4;	//更换波形

uint freq = 3906;										//定时数值×16^(-6)×256 = 波形频率 例程使用1KHZ
uint number=1,n=0,THHL,i;

//正弦波段码
unsigned code sin[256]={   
                          0x80,0x83,0x85,0x88,0x8A,0x8D,0x8F,0x92,   
                          0x94,0x97,0x99,0x9B,0x9E,0xA0,0xA3,0xA5,   
                          0xA7,0xAA,0xAC,0xAE,0xB1,0xB3,0xB5,0xB7,   
                          0xB9,0xBB,0xBD,0xBF,0xC1,0xC3,0xC5,0xC7,   
                          0xC9,0xCB,0xCC,0xCE,0xD0,0xD1,0xD3,0xD4,   
                          0xD6,0xD7,0xD8,0xDA,0xDB,0xDC,0xDD,0xDE,   
                          0xDF,0xE0,0xE1,0xE2,0xE3,0xE3,0xE4,0xE4,   
                          0xE5,0xE5,0xE6,0xE6,0xE7,0xE7,0xE7,0xE7,   
                          0xE7,0xE7,0xE7,0xE7,0xE6,0xE6,0xE5,0xE5,   
                          0xE4,0xE4,0xE3,0xE3,0xE2,0xE1,0xE0,0xDF,   
                          0xDE,0xDD,0xDC,0xDB,0xDA,0xD8,0xD7,0xD6,   
                          0xD4,0xD3,0xD1,0xD0,0xCE,0xCC,0xCB,0xC9,   
                          0xC7,0xC5,0xC3,0xC1,0xBF,0xBD,0xBB,0xB9,   
                          0xB7,0xB5,0xB3,0xB1,0xAE,0xAC,0xAA,0xA7,   
                          0xA5,0xA3,0xA0,0x9E,0x9B,0x99,0x97,0x94,   
                          0x92,0x8F,0x8D,0x8A,0x88,0x85,0x83,0x80,   
                          0x7D,0x7B,0x78,0x76,0x73,0x71,0x6E,0x6C,   
                          0x69,0x67,0x65,0x62,0x60,0x5D,0x5B,0x59,   
                          0x56,0x54,0x52,0x4F,0x4D,0x4B,0x49,0x47,   
                          0x45,0x43,0x41,0x3F,0x3D,0x3B,0x39,0x37,   
                          0x35,0x34,0x32,0x30,0x2E,0x2D,0x2C,0x2A,   
                          0x29,0x28,0x26,0x25,0x24,0x23,0x22,0x21,   
                          0x20,0x1F,0x1E,0x1D,0x1D,0x1C,0x1C,0x1B,   
                          0x1B,0x1A,0x1A,0x1A,0x19,0x19,0x19,0x19,   
                          0x19,0x19,0x19,0x19,0x1A,0x1A,0x1A,0x1B,   
                          0x1B,0x1C,0x1C,0x1D,0x1D,0x1E,0x1F,0x20,   
                          0x21,0x22,0x23,0x24,0x25,0x26,0x28,0x29,   
                          0x2A,0x2C,0x2D,0x2F,0x30,0x32,0x34,0x35,   
                          0x37,0x39,0x3B,0x3D,0x3F,0x41,0x43,0x45,   
                          0x47,0x49,0x4B,0x4D,0x4F,0x52,0x54,0x56,   
                          0x59,0x5B,0x5D,0x60,0x62,0x65,0x67,0x69,   
                          0x6C,0x6E,0x71,0x73,0x76,0x78,0x7B,0x7D   
                                                                   };   
//三角波段码
unsigned code thr[256]={      
                          0x80,0x81,0x82,0x83,0x84,0x85,0x86,0x87,   
                          0x88,0x89,0x8A,0x8B,0x8C,0x8D,0x8E,0x8F,   
                          0x90,0x91,0x92,0x93,0x94,0x95,0x96,0x97,   
                          0x98,0x99,0x9A,0x9B,0x9C,0x9D,0x9E,0x9F,   
                          0xA0,0xA1,0xA2,0xA3,0xA4,0xA5,0xA6,0xA7,   
                          0xA8,0xA9,0xAA,0xAB,0xAC,0xAD,0xAE,0xAF,
                          0xB0,0xB1,0xB2,0xB3,0xB4,0xB5,0xB6,0xB7,   
                          0xB8,0xB9,0xBA,0xBB,0xBC,0xBD,0xBE,0xBF,   
                          0xBF,0xBE,0xBD,0xBC,0xBB,0xBA,0xB9,0xB8,   
                          0xB7,0xB6,0xB5,0xB4,0xB3,0xB2,0xB1,0xB0,
                          0xAF,0xAE,0xAD,0xAC,0xAB,0xAA,0xA9,0xA8,   
                          0xA7,0xA6,0xA5,0xA4,0xA3,0xA2,0xA1,0xA0,   
                          0x9F,0x9E,0x9D,0x9C,0x9B,0x9A,0x99,0x98,   
                          0x97,0x96,0x95,0x94,0x93,0x92,0x91,0x90,   
                          0x8F,0x8E,0x8D,0x8C,0x8B,0x8A,0x89,0x88,   
                          0x87,0x86,0x85,0x84,0x83,0x82,0x81,0x80,   
                          0x7F,0x7E,0x7D,0x7C,0x7B,0x7A,0x79,0x78,   
                          0x77,0x76,0x75,0x74,0x73,0x72,0x71,0x70,   
                          0x6F,0x6E,0x6D,0x6C,0x6B,0x6A,0x69,0x68,   
                          0x67,0x66,0x65,0x64,0x63,0x62,0x61,0x60,   
                          0x5F,0x5E,0x5D,0x5C,0x5B,0x5A,0x59,0x58,   
                          0x57,0x56,0x55,0x54,0x53,0x52,0x51,0x50,   
                          0x4F,0x4E,0x4D,0x4C,0x4B,0x4A,0x49,0x48,   
                          0x47,0x46,0x45,0x44,0x43,0x42,0x41,0x40,   
                          0x40,0x41,0x42,0x43,0x44,0x45,0x46,0x47,   
                          0x48,0x49,0x4A,0x4B,0x4C,0x4D,0x4E,0x4F,   
                          0x50,0x51,0x52,0x53,0x54,0x55,0x56,0x57,   
                          0x58,0x59,0x5A,0x5B,0x5C,0x5D,0x5E,0x5F,   
                          0x60,0x61,0x62,0x63,0x64,0x65,0x66,0x67,   
                          0x68,0x69,0x6A,0x6B,0x6C,0x6D,0x6E,0x6F,   
                          0x70,0x71,0x72,0x73,0x74,0x75,0x76,0x77,   
                          0x78,0x79,0x7A,0x7B,0x7C,0x7D,0x7E,0x7F    
                                                                   }; 

//方波段码																																	 
unsigned code squ[256]={
													0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
													0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
													0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
													0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
													0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
													0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
													0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
													0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
													0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
													0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
													0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
													0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
													0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
													0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
													0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
												  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
													0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
													0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,	
													0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
													0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
													0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
													0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,	
													0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
													0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,													
													0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
													0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,	
													0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
													0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,			
													0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
													0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,	
													0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
													0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff												
														};
															

//10ms延时函数
void delay_10ms(uchar i)
{
	//毫秒级延时函数
	//在12MHZ下晶振下，大约延时10ms/次
    uchar a,b,c;
		for(c = i; c > 0; --c)
	    for(b = 129; b > 0; b--)
				for(a = 38; a > 0; a--);
}

//定时器0初始化
void Timer0Init(void)
{
	unsigned int THHL;
	TMOD &= 0xF0;				//定时器1失效
	TMOD |= 0x01;				//定时器0，16位计数
	THHL=65536-freq;
	TL0 =THHL%256;			//设置定时初值
	TH0 =THHL/256;			//设置定时初值
	TF0 = 0;						//清除TF0标志
	TR0 = 1;						//定时器0开始计时
	ET0=1;							//开定时器0中断
	EA=1;								//开总中断
	PT0=0;							//定时器0中断最优
}

void main()
{
	/*指示灯初始化，全部熄灭*/
//	triangular_wave_LED3  = 1;
//	square_wave_LED2			= 1;
//	sine_wave_LED1				= 1;
	
	Timer0Init();//初始化定时器0
	
	while(1)
	{
		if(change_wave_Key == 0)
		{
			delay_10ms(1);//延时消抖
			if(change_wave_Key == 0)
			{
				while(!change_wave_Key);//松手检测
				number++;
				
				if(number == 5)
				{
					number = 0;
				}
			}
		}
		
		switch(number)
		{
			case 1:	{DI=sin[n]; break;}//正弦波
			case 2: {DI=thr[n]; break;}//三角波
			case 3: {for(i=0;i<256;i++){DI=squ[i];} break;}//方波
			case 4:	{DI=256-n; break;}//锯齿波
			default:{break;}
		}
		
	}
}

//定时器0中断处理函数
void Timer0_Routine() interrupt 1
{
	THHL=65536-freq;
	TL0=THHL%256;
	TH0=THHL/256;  
	if(n>=255) 
	{n=0;} 
	else 
	{n++;}   
}

电路仿真及代码例程
链接：https://share.weiyun.com/ALLrnKTu 密码：cchvph

（5）参考文献

基于51单片机的DAC0832波形发生器

由于作者水平有限，如有错误望指摘。