Design of automatic digital voltmeter based on 51 single chip microcomputer and ADC0808 ADC0809

Preface:

Previously, we talked about the automatic digital voltmeter based on the digital tube display. Next, let’s talk about the related designs based on LCD1602 display, which use TI’s ADC0808 and ADC0809 respectively.

Hardware and software design

Based on 51 MCU + ADC0808 + LCD1602, the test voltage range is 2.1~25V (if it exceeds this range, the program will be stuck), and the accuracy is less than 0.05

The simulation diagram is as follows:

Some of the code is as follows:

#include  

#define LEDDATA P0

#define v20_on {s3=0;s2=0;s1=1;} //Macro defines different ranges and different switch states

#define v2_on {s3=0;s2=1;s1=0;}

#define v02_on {s3=1;s2=0;s1=0;}

unsigned char code dispcode[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x00};

unsigned char dispbuf[8]={0,0,0,0,0,0,0,0};

unsigned char getdata;

unsigned long temp;

unsigned char i,k,l,m;

unsigned char code  mytable0[]=" Welcome to use  ";

unsigned char code  mytable1[]="Auto Voltmeter!";

unsigned char code line0[]=" Voltmeter "; //Initialize display 

unsigned char code line1[]=" Value:     V ";

//Pin definition

sbit lcdrs=P2^0;

sbit lcden=P2^1;

sbit s3=P3^7;  

sbit s2=P3^6;

sbit s1=P3^5;

sbit OE=P3^0; 

sbit EOC=P3^1;

sbit ST=P3^2;

void delay(unsigned int z) //delay sub-function z*1ms 

{

unsigned int x,y;

for(x=z;x>0;x--)

for(y=110;y>0;y--);

}

void write_com(unsigned char c) //write command subfunction 

{

lcdrs=0; //Low level selects write instruction 

lcden=0;                

LEDDATA=c; //Write the command into port P0 

delay(5); //Refer to the timing diagram 

lcden=1; //enable 

delay(5); //Read instruction 

lcden=0; //disable enable  

} 

void write_data(unsigned char d) //write data sub-function 

{

lcdrs=1; //High level selects writing data 

LEDDATA=d; //Write data into P0 port 

delay(5); //Refer to the timing diagram 

lcden=1; //enable 

delay(5); //Read data 

lcden=0;          //disable enable 

} 

void initialize() //LCD initialization function 

{   

    unsigned char num;

lcden=0;

write_com(0x38); //Set 16x2 display, 5x7 dot matrix display, 8-bit data interface 

write_com(0x0c); //00001DCB, D (display on/off), C (whether to display the cursor), B (cursor flashes, cursor does not display) 

write_com(0x06); //000001N0, N (address pointer +-1)

write_com(0x01); //Clear screen command The screen must be cleared each time the next screen content is displayed            

write_com(0x80+0x10); //First line, display at the top of the grid   

for(num=0;num<17;num++)        

{

write_data(mytable0[num]); 

delay(10);

}

write_com(0x80+0x50); //The second line, starting from the first grid 

for(num=0;num<15;num++)       

{

write_data(mytable1[num]); 

delay(10); 

}

for(num=0;num<16;num++)

{

write_com(0x1c); //0001(S/C)(R/L)**; S/C: high level moves characters, low level moves cursor; R/L: high level moves left, low level moves right 

delay(300);

}

   delay(1000); 

write_com(0x01); //Clear screen command The screen must be cleared each time the next screen content is displayed 

write_com(0x80);           

for(num=0;num<14;num++)     

{

write_data(line0[num]);

delay(10);

}

write_com(0x80+0x40);         

for(num=0;num<15;num++)        

{

write_data(line1[num]);

delay(10);

}

} 

Based on 51 single chip microcomputer + ADC0809 + LCD1602, the test voltage range is 0~5V, and the accuracy is about 0.01

The AT89C51 single-chip microcomputer is the core and plays a control role. The system includes LCD1602 liquid crystal display circuit, reset circuit, clock circuit, and analog-to-digital conversion circuit. The design idea is divided into five modules: reset circuit, crystal oscillator circuit module, AT89C51, LCD1602 liquid crystal display circuit, and analog-to-digital converter circuit.

Some of the code is as follows:

//: Digital voltmeter **

//: Use LCD to display the detected voltage, with an accuracy of 0.05V and a range of 0 to 5V. **

#include"includes.h"

#define TIME0H 0x3C

#define TIME0L 0xB0

uchar uc_Clock=0; //Timer 0 interrupt count

bit b_DATransform=0;

//<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

//<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<把电压显示在LCD上>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

//<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

void vShowVoltage(uint uiNumber)

{

float ucaNumber[3],ucCount;

if(uiNumber>999)

uiNumber=999;

ucaNumber[0]=uiNumber/100; //Store each digit of the calculated number into the array.

ucaNumber[1]=(uiNumber-100*(int)ucaNumber[0])/10;

ucaNumber[2]=uiNumber-100*(int)ucaNumber[0]-10*ucaNumber[1];

for(ucCount=0;ucCount<3;ucCount++)

{

vShowOneChar(ucaNumber[ucCount]+48); //Output one by one from the first digit to the last digit.

if(ucCount==0)

vShowOneChar('.');

}

}

//*************************************************************************************************

//*   *

//*   ********************************Main function******************************   *

//*   *

//*************************************************************************************************

void main()

{

TMOD=0x01; //Timer 0, mode 1.

TH0=TIME0H;

TL0=TIME0L;

TR0=1; //Start the timer.

ET0=1; //Turn on timer interrupt.

EA=1; //Open the general interrupt

vdInitialize();

vWriteCMD(0x84);    //Write the display start address (the 4th position in the first line)

vShowChar("voltage");

vWriteCMD(0xC9);     

vShowChar("(V)");

while(1)

{

if(b_DATransform==1)

{

b_DATransform=0;

vWriteCMD(0xC4);

vShowVoltage(uiADTransform());

}

}

}

//<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

//<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<定时器0中断函数>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

//<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

void t0() interrupt 1

{

if(uc_Clock==0)

{

uc_Clock=5;

b_DATransform=1;

}

else

uc_Clock--;

TH0=TIME0H;    //Restore timer 0.

TL0=TIME0L;

}

File address:

Link: https://pan.baidu.com/s/146k5nKjulFsZeTJUKEvQDQ

Extraction code: cukz