ADC0808/9 signal acquisition developed by single chip microcomputer

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 一、题目

ADC0808信号采集

二、要求

1、画出实验的流程图

2、编写源程序并进行注释

3、记录实验过程

4、记录程序运行结果截图

三、过程及结果分析

利用LCD1602和AD0808Realize simple AC signal zero-crossing detection and frequency analysis.When signal amplitude changes are required（满量程的5%—95%）,Does not affect detection results.The result of the frequency detection is passedLCD1602The first line of is displayed,When the signal crosses zero,能够通过P2.6Output a pulse width of 5μs的脉冲信号.

1. According to the above experiment content,在Proteus 环境下建立图1所示原理图,并将其保存为ADC0808_self.DSN 文件.

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图1：实验电路图 

2. 编写源程序,将其保存为ADC0808_self.c,运行Keil开发环境,建立工程ADC0808_self.uV2,CPU 为AT89C51,包含启动文件STARTUP.A51.

3. 将C 语言源程序ADC0808_self.c 加入工程ADC0808_self.uV2,并设置工程ADC0808_self.uV2 属性,将其晶振频率设置为12MHz,选择输出可执行文件,仿真方式为选择硬仿真,并选择其中的“PROTEUS VSM MONITOR 51 DRIVER”仿真器.

4.构造（Build）工程ADC0808_self.uV2.如果输入有误进行修改,直至构造正确,生成可执行程序ADC0808_self.hex 为止.为AT89C51 设置可执行程序ADC0808_self.hex.

5. 运行程序,观察计算结果,并验证其是否正确.改变RV1 the tap position,Thereby changing the amplitude of the input signal,Observe whether the calculation result is correct.Change the frequency of the signal transmitter,Verify again that it functions correctly.（注意：Because it is a soft simulation,So the speed of signal acquisition is limited,Therefore, the frequency of the input AC signal cannot be too high,可以在200Hz以内尝试）.

实验结果如下：

1）Set the potentiometer to full scale90%,At this time, the amplitude of the signal is the maximum value90%

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图2：The potentiometer is adjusted to full scale90%

2）Set the potentiometer to full scale50%,The amplitude of the signal at this time is half of the maximum value

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图3：The potentiometer is adjusted to full scale50%

3）The potentiometer is adjusted to full scale10%,At this time, the amplitude of the signal is the maximum value10%

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图4：The potentiometer is adjusted to full scale10%

四、流程图

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图5：实验流程图

        LCD1602control method by pressing 3.7method shown in sectionADC0808control method by pressing 3.8.1performed as indicated.Here is mainly how to realize the detection method of zero-crossing point.It cannot be used to judge whether the collected data is 0 的方法来实现,Because your acquisition time may not be strictly aligned with the zero-crossing time.但是,我们注意到在 0 The polarity of the signal on both sides of the point changes,We can take advantage of this feature to achieve zero-crossing detection.A sine wave has two zero crossings per cycle,因此,1s Divide by the number of internal zero crossings 2 is the frequency of the signal.

        因此,This can be done in the program.Every time a new data is collected, it is necessary to check whether the data is positive or negative.当这个数大于 128 时是正数,当它小于 128 is negative.Determine whether the positive and negative polarities of the current data are consistent with the positive and negative polarities of the previous data,如果不一致,It means that a zero-crossing has passed,Record it in the times counter.

        ADC0808 的 CLK Still using the timer T1 来实现,可以将其设置为 50kHz（It can be higher when implemented in hardware,No matter how high the software simulation is, it will be difficult to achieve）.利用定时器 T0 实现 50ms 定时,And cooperate with the software to realize 1s clock time.采用 12M 晶振时,T0 采用方式 1,Then the disposal should be（TH0=0x3C,TL0=0xB0）.

        但是,Because the interrupt handler needs a certain response time,Therefore, this parameter is only a theoretical calculation result,To be adjusted slightly according to the actual situation. 同样 T1 There may also be a certain gap between the theoretical calculated value and the actual output value,Adjustments are also made.

五、源代码

#include "reg51.h"    //  MCU register header file#include "intrins.h"  // _ nop_()Header files for other functionssbit LCD_RS=P2^0;  //寄存器选择位,将RS位定义为P2.0引脚sbit LCD_RW=P2^1; // 读写选择位,将RW位定义为P2.1引脚sbit E=P2^2;     //使能信号位,将E位定义为P2.2引脚sbit BF=P1^7;    // P0.7is the busy flagsbit CLK=P2^3;   // 设置时钟端口sbit start=P2^4; sbit oe=P2^5;  sbit eoc=P2^7; sbit out_pulse=P2^6;  // P2^6端口输出5us脉冲sbit p30=P3^0; #define uchar unsigned char#define uint unsigned intuchar n=0;uchar flag=0; void delay1ms()// 定义延时1ms函数{   		unsigned char i,j;		 	for(i=0;i<10;i++)	  	for(j=0;j<33;j++);		  } void delay(unsigned int n)	//定义延时nms函数 {   	unsigned int i;	for(i=0;i<n;i++)	delay1ms(); } bit BusyTest(void) //检查子程序,为1busy,为0not busy  {    	bit result;		LCD_RS=0;           	LCD_RW=1;    	E=1;           	_nop_();       	_nop_();    	_nop_();    		_nop_();       	result=BF;  		E=0;    	return result;  }void Write_com (uchar cmd)		//写命令子程序{       while(BusyTest()==1); 	 LCD_RS=0;             	 LCD_RW=0;       // RS/RW都是0的时,写指令	 E=0;                                               	 _nop_();	 _nop_();            	 P1=cmd;   // 写指令操作   	 _nop_();//运行一个机器周期	 _nop_();  	 _nop_();	 _nop_();               	 E=1;                   	 _nop_();	 _nop_();	 _nop_();	 _nop_();               	  E=0;  // EWrite from high to low } void WriteAddress(unsigned char x) {     Write_com(x|0x80); //Display location is"80H+地址码x"	 } void WriteData(unsigned char y)   //写数据子程序 {    while(BusyTest()==1);  	  LCD_RS=1; 	  LCD_RW=0;	  E=0;                                  	  P1=y;   // 执行操作	  _nop_(); //运行一个机器周期	  _nop_(); 	  _nop_();    	nop_();     	  E=1;         	  _nop_(); 	  _nop_();	  _nop_();	  _nop_();       	  E=0;          }void LcdInt(void) //初始化LCD{   	delay(15);  // 延时15ms,让电源稳定   	Write_com(0x38);  //设置显示,即16×2显示,5×7点阵,8位数据接口	delay(5);   //延时5ms　	Write_com(0x0c);  //设置显示：显示开,有光标,光标闪烁	delay(5);	Write_com(0x06);  D=1,S=0地址自加1	delay(5);											  	Write_com(0x01);  // Clear screen operation	delay(5); }void sysinit()			   //系统初始化{                             	TMOD = 0x21;  //  设定定时器T1The way it works is automatic reloading8位计数器,T0工作方式为方式1（16位计数器）	TH1=0xfd;  //Generated using interruptsCLK信号	TL1=0xfd;  	EA=1;     //开总中断  		ET1=1;  	//T1中断允许	TR1=1;     //启动定时器T1	TH0=0x45;    // 置初值	TL0=0x00;  //50MS定时		ET0=1;	 //T0中断允许	TR0=1;	 //启动定时器T0	start=0;  //A／DThe conversion start signal starts at 0	oe=0;   //The data output enable signal starts at 0}void t0(void) interrupt 1	//T0中断服务程序{	ET0=0;     // 关中断	TH0=0X45;  	TL0=0X00; 	n++;	if(n==20) {flag=1;n=0;}		 //循环20次,即完成1S定时		ET0=1;						//开T0中断允许	}void t1(void) interrupt 3		// 定时器T1中断服务程序{	ET1=0;    // 关闭中断	CLK=~CLK;  // 每中断一次,取上一次clkThe opposite of the signal,Thus was born50KHzperiodic square wave signal	ET1=1;    //开启中断}unsigned char adc()//数据采集子程序{   unsigned  char  Temp;   start=1;   start=0;  //启动信号   while (!eoc); // A／D转换结束信号,0Indicates that the conversion is complete,可以输出   P0=0xff; // Write before read1    oe=1;	   Temp=P0; //读取采集数据   oe=0;   return(Temp); }void display(uint a)//显示子函数{	uint bai,shi,ge;	bai=a/100;	shi=(a-bai*100)/10;	ge=a%10;	WriteAddress(2);	WriteData(0x30+bai);    //显示百位	WriteData(0x30+shi);     //显示十位	WriteData(0x30+ge);     //显示个位}void main()    // 定义主程序{	uint temp1,temp2;	uchar f=0;	LcdInt();	delay(5);	sysinit();	CLK=0;	WriteAddress(0); //从第0行开始显示	WriteData('f');   //显示 f ; 等	WriteData(':');  	WriteAddress(5);     //从第5行开始显示	WriteData('H');	    //显示H	WriteData('z');      //显示z	while(1)           //一直循环	{				temp2=temp1;		temp1=adc();//ad采集		if(((temp1>=128)&&(temp2<=128))||((temp1<=128)&&(temp2>=128)))	//The polarities of the two acquisitions are opposite at zero-crossing		{			f++;			out_pulse=1;   //Pulse signal is output at zero crossing			_nop_();	   //运行一个机器周期			_nop_();			_nop_();			_nop_();			_nop_();			out_pulse=0;     //产生5us的脉冲信号		}		if(flag==1)      //1sThen calculate the frequency		{			flag=0;     // 标志位清0			f=f/2;     // Two zero crossings in one cycle			display(f);     //显示频率			f=0;		}	}}

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