applictaions.8051

8/3/2019 Applictaions.8051

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APPLICATIONS OF 8051

Analog to Digital Conversion

(ADC 0804)

DC-Voltmeter

by. Engr. Khurram Hashmi


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Introduction

One of the applications that an 8051 micro-Controllermight provide is in cohesion with Analog to DigitalConversion ICs

ADC 0804 or ADC 0808

ADC 01101011


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Flow Representation

ADC converts Analog input to Digital8 bit output

8051 handles this data

Algorithms implemented to converthex standard format to ASCII anddisplayed on LCD

ADC 01101011

8051

LCD Display

8 bit

voltage signal


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Circuit Diagram


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Voltage Divider Input

Voltage Input takenacross voltage Divider.

Max of 5volts appears atInput pins

8bit

DB0-DB7 to 8051


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LCD Display Output

Output read at Port 1and intrinsicallyprocessed as Hexvalues

Algorithm converts hexvalued to ASCIIequivalents and Displays

on LCD


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Algorithm

Lcd.h

A Library file that defines function prototypesused in files

Lcd.cContains functions involved in coveting hex data

to ASCII and writing it to LCD

Voltmeter.cContains functions for reading ADC output and

passes this to LCD write functions in Lcd.c


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Lcd.h a header file

#ifndef __LCD_H__

#define __LCD_H__

#include

#define lcd_port P2 // Where the LCD is attached and output to LCD shall be sent

#define rs P3_0 // READ#define rw P3_1 // WRITE

#define en P3_2 // ENABLE

#define flag P2_7 // D7 of LCD the Busy Flag

void wrt_cmd(unsigned char);

void wrt_data(unsigned char);

void wrt_string(unsigned char*);

void LCD_INI(void);

void busy(void);

void hex2lcd(unsigned char);

#endif

Function prototypes

LCD


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Voltmeter.c

#include

#include "lcd.h"

#define adc_port P1 //Port where ADC output is attached

#define rd P3_7 //Assigning Read signal P3.7

#define wr P3_6 //Assigning Write signal P3.6

#define cs P3_5 //Assigning Chip Select P3.5

#define intr P3_4 //Assigning INTR signal P3.4

void conv(); // Start of conversion function called

void read(); //Read ADC function called

unsigned int adc_avg , adc; //defining two integers

ADC


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ADC 0804 Timing diagram


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voltmeter.c continued

void conv( )

{

cs = 0; //Make CS low

wr = 0; //Make WR low

wr = 1; //Make WR high

cs = 1; //Make CS high

while(intr); //Wait for INTR to go low

}

void read( )

{

cs = 0; //Make CS low

rd = 0; //Make RD lowadc = adc_port; //Read ADC port

rd = 1; //Make RD high

cs = 1; //Make CS high

}

Low Active pins on ADC

Activates ADC output

When CS=0Low to High transition of WRStarts data conversionAnalog to BCD

at the end of which INTR pin goes lowas an indication to the CPU

Low Active pins on ADCrestored to high for next reading


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void main() {

char i; //a counter variable i

LCD_INI(); //Initiate LCD

while(1){ //Forever loop

adc_avg = 0;

for(i=0;i


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Lcd.c

void busy(){

flag=1; //Set flag

rs=0; //RS low select instruction command register to send command

rw=1; //RW high reading informtion

while(flag!=0) / /untill LCD hasnt completed its operation

{

en=0; //high to low

en=1; //Low to high

}

}

void wrt_cmd(unsigned char val_lcd)

{

busy(); // check if LCD is NOT BUSY

lcd_port=val_lcd; // send data to LCD port

rs=0; /Instruction Register Selected

rw=0; //for writing information

en=1; //high to low latch for enable

en=0;

For writing a Command to the LCDSuch as clear screen,cursor shift

EN high to Low transition Latches

in Information

Check to see ifLCD is Busy


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Lcd.c continued.

void wrt_data(unsigned char dat)

{

busy();

lcd_port=dat;

rs=1;

rw=0;en=1; //high to low

en=0; //to latch the data present on the data pins

}

void wrt_string(unsigned char *string)

{while(*string)

wrt_data(*string++);

}

For Writing Data to LCDAs A or 55.3 etc

EN high to Low transition Latchesin Information

For Writing String Data to LCD

As V(DC):Achieved through incrementinggradually and passing to LCD


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Lcd.c continued.

void LCD_INI(void)

{

wrt_cmd(0X30); //initiate LCD

wrt_cmd(0X0C);

wrt_cmd(0X01); //clear LCD

wrt_cmd(0X06); //shift cursor right

}

Initiates the LCD


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void hex2lcd ( unsigned char hex)

{ //converts hex to AASCII and displays on LCD

char temp1, temp2; //temporary variables

temp1 = hex;

temp2=0;

do{

temp1 = temp1-100;

if(temp1>=0)

temp2++;

} while(temp1>=0);

if(temp2>0)

wrt_data(temp2+0x30);

temp2=0;

temp1 = temp1+100;

do{

temp1 = temp1-10;

if(temp1>=0)

temp2++;

} while(temp1>=0);

wrt_data(temp2+0x30);

temp2 = temp1+10;

wrt_data(temp2+0x30);}

Converts HEX values to ASCII and Sends to LCD Port

hex

Hex ASCII

30 031 1

. .

57 9

Tens

digitHundreds

digitUnitsdigit

+30 H +30 H +30 H

Unit

DgitTens digit

Fractional

digit

LCD


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by

Engr. Khurram Hashmi

Faculty of Engineering

University of Central Punjab

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