Engineers Garage

  • Electronic Projects & Tutorials
    • Electronic Projects
      • Arduino Projects
      • AVR
      • Raspberry pi
      • ESP8266
      • BeagleBone
      • 8051 Microcontroller
      • ARM
      • PIC Microcontroller
      • STM32
    • Tutorials
      • Audio Electronics
      • Battery Management
      • Brainwave
      • Electric Vehicles
      • EMI/EMC/RFI
      • Hardware Filters
      • IoT tutorials
      • Power Tutorials
      • Python
      • Sensors
      • USB
      • VHDL
    • Circuit Design
    • Project Videos
    • Components
  • Articles
    • Tech Articles
    • Insight
    • Invention Stories
    • How to
    • What Is
  • News
    • Electronic Product News
    • Business News
    • Company/Start-up News
    • DIY Reviews
    • Guest Post
  • Forums
    • EDABoard.com
    • Electro-Tech-Online
    • EG Forum Archive
  • DigiKey Store
    • Cables, Wires
    • Connectors, Interconnect
    • Discrete
    • Electromechanical
    • Embedded Computers
    • Enclosures, Hardware, Office
    • Integrated Circuits (ICs)
    • Isolators
    • LED/Optoelectronics
    • Passive
    • Power, Circuit Protection
    • Programmers
    • RF, Wireless
    • Semiconductors
    • Sensors, Transducers
    • Test Products
    • Tools
  • Learn
    • eBooks/Tech Tips
    • Design Guides
    • Learning Center
    • Tech Toolboxes
    • Webinars & Digital Events
  • Resources
    • Digital Issues
    • EE Training Days
    • LEAP Awards
    • Podcasts
    • Webinars / Digital Events
    • White Papers
    • Engineering Diversity & Inclusion
    • DesignFast
  • Guest Post Guidelines
  • Advertise
  • Subscribe

How to interface LDR with ADC0808 using interrupt clock from 8051 microcontroller (AT89C51)- (Part 26/45)

By Himanshu Choudhary August 16, 2010

This circuit demonstrates the principle and operation of interfacing an LDR with ADC0808 using the controller AT89C51. This is an 8 channel ADC i.e., it can take eight input signals. The output is displayed on the LCD.

 

 


 

 

ADC0808 is an 8-bit resolution IC with eight input pins. LDR is used to provide the analog input. The output of the LDR is displayed on a 16×2 LCD.  A clock of frequency 500 KHz is generated using Timer0 in the interrupt mode. To enable the interrupt, the value of the register IE is set to 0x82 (Refer interfacing ADC 0808 with interrupt clock).
 
The output pins of ADC are connected to the port P0 of the AT89C51. The pin10 of the ADC is connected to pin8 (P1.7) of the controller for clock input. ALE, pin22 of the ADC is connected to pin1 (P1.0) of controller. OE, pin9 of the ADC is connected to pin4 (P1.3) of controller. SC, pin6 of the ADC is connected to pin2 (P1.1) of the controller. EOC, pin number 7 is connected to pin 3 (P1.2) of controller. Selector pins A (25), B (24) and C (24) of ADC are connected to the pins 4, 5 and 6 of the controller respectively.
 

Port P2 (pins 21-28) of controller is used to send the data to the LCD (pins 7-14). RS (pin4) of LCD is connected to P3.0 (pin 10) of controller. R/W (pin5) of LCD is connected to P3.1 (pin11) of the controller. Enable pin, EN, pin6 of LCD will connect to P3.6 of controller (Refer LCD interfacing).
 
The controller continuously monitors the output of the ADC. The output of the LDR varies with the intensity of light. The value ADC output varies from 0 to 255. The output of ADC is converted to decimal form and then displayed on the LCD (Refer displaying number on LCD). If the output of any of the LDR varies, the corresponding change is reflected on LCD screen.

 

 

Project Source Code

###

// Program to interface LDR using ADC 0808. The output of LDR is displayed on LCD. Controller interrupt is used to generate the clock for driving ADC 0808.
#include<reg51.h>
sbit ale=P1^0;  //address latch enable
sbit oe=P1^3;  //output enable
sbit sc=P1^1;  //start conversion
sbit eoc=P1^2;  //end of conversion
sbit clk=P1^7;  // clock
sbit ADD_A=P1^4;  // Address pins for selecting input channels.
sbit ADD_B=P1^5;
sbit ADD_C=P1^6;
sfr lcd_data_pin=0xA0;  //P2 port
sbit rs=P3^0;
sbit rw=P3^1;
sbit en=P3^6;
sfr input_port=0x80;  //P0 port
unsigned int bitvalue,decimal_value,key,left_value,value,number,ascii1,ascii2,ascii3,flag,key1;

void timer0() interrupt 1  // Function to generate clock of frequency 500KHZ using Timer 0 interrupt.
{
clk=~clk;
}

void delay(unsigned int count)  // Function to provide time delay in msec.
{
int i,j;
for(i=0;i<count;i++)
for(j=0;j<1275;j++);
}

void lcd_command(unsigned char comm)  //Function to send command to LCD.
{
lcd_data_pin=comm;
en=1;
rs=0;
rw=0;
delay(10);
en=0;
}

void lcd_data(unsigned char disp)  //Function to send data to LCD.
{
lcd_data_pin=disp;
en=1;
rs=1;
rw=0;
delay(10);
en=0;
}

lcd_dataa(unsigned char *disp)  //Function to send string data to LCD.
{
int x;
for(x=0;disp[x]!=0;x++)
{
  lcd_data(disp[x]);
}
}

void lcd_ini()  //Function to inisialize the LCD
{
lcd_command(0x38); 
delay(5);
lcd_command(0x0F); 
delay(5);
lcd_command(0x80);  //Force cursor to blink at line 1 positon 0
delay(5);
}

  void BCD()  // Binary to decimal conversion to send the data to LCD
{
  key1++;
  key=0;
  flag=0;
    number=input_port;
    value=number%10;
number=number/10;
ascii1=value+48;
if(number!=0)
{
  value=number%10;
  number=number/10;
  ascii2=value+48;
    flag=1;
}
else
{
   ascii2=48;
   flag=1;
}
if(number!=0)
{
  value=number%10;
    number=number/10;
    ascii3=value+48;
    key=2;
}
else
{
  ascii3=48;
  key=2;
}
if(key==2)
lcd_data(ascii3);
if(flag==1)
lcd_data(ascii2);
lcd_data(ascii1);
if(key1==3)
{
key1=0;
ascii3=0;
ascii2=0;
ascii1=0;
delay(10);
} 
}

void adc()  //Function to drive ADC
{
while(1)
{
  ADD_C=0;  // Selecting input channel 2 using address lines
  ADD_B=0;
  ADD_A=1;
  delay(2);
  ale=1;
  delay(2);
  sc=1;
  delay(1);
  ale=0;
  delay(1);
  sc=0;
  while(eoc==1);
  while(eoc==0);
  oe=1;
  BCD();
  lcd_command(0x88);
  delay(2);
  oe=0;
}
}

void main()
{
eoc=1;
ale=0;
oe=0;
sc=0;
key1=0;
TMOD=0x02;  //timer0 setting for generating clock of 500KHz using interrupt enable mode.
TH0=0xFD;
IE=0x82;
TR0=1;
lcd_ini();
lcd_dataa("Value : ");
lcd_command(0x88);
adc();
}

###

 


Circuit Diagrams

Circuit-Diagram-Interfacing-LDR-ADC0808-Using-Interrupt-Clock-8051-Microcontroller-AT89C51

Project Components

  • AT89C51 Microcontroller
  • IC ADC0808
  • LCD
  • LDR
  • Preset

Project Video


Filed Under: 8051 Microcontroller
Tagged With: 8051, clock, interrupt, ldr, microcontroller
 

Next Article

← Previous Article
Next Article →

Questions related to this article?
👉Ask and discuss on Electro-Tech-Online.com and EDAboard.com forums.



Tell Us What You Think!! Cancel reply

You must be logged in to post a comment.

EE TECH TOOLBOX

“ee
Tech Toolbox: 5G Technology
This Tech Toolbox covers the basics of 5G technology plus a story about how engineers designed and built a prototype DSL router mostly from old cellphone parts. Download this first 5G/wired/wireless communications Tech Toolbox to learn more!

EE Learning Center

EE Learning Center
“engineers
EXPAND YOUR KNOWLEDGE AND STAY CONNECTED
Get the latest info on technologies, tools and strategies for EE professionals.

HAVE A QUESTION?

Have a technical question about an article or other engineering questions? Check out our engineering forums EDABoard.com and Electro-Tech-Online.com where you can get those questions asked and answered by your peers!


RSS EDABOARD.com Discussions

RSS Electro-Tech-Online.com Discussions

Featured – LoRa/LoRaWan Series

  • What is the LoRaWAN network and how does it work?
  • Understanding LoRa architecture: nodes, gateways, and servers
  • Revolutionizing RF: LoRa applications and advantages
  • How to build a LoRa gateway using Raspberry Pi
  • How LoRa enables long-range communication
  • How communication works between two LoRa end-node devices

Recent Articles

  • RPi Python Programming 21: The SIM900A AT commands
  • RPi Python Programming 22: Calls & SMS using a SIM900A GSM-GPRS modem
  • RPi Python Programming 23: Interfacing a NEO-6MV2 GPS module with Raspberry Pi
  • RPi Python Programming 24: I2C explained
  • RPi Python Programming 25 – Synchronous serial communication in Raspberry Pi using I2C protocol

EE ENGINEERING TRAINING DAYS

engineering

Submit a Guest Post

submit a guest post
Engineers Garage
  • Analog IC TIps
  • Connector Tips
  • Battery Power Tips
  • DesignFast
  • EDABoard Forums
  • EE World Online
  • Electro-Tech-Online Forums
  • EV Engineering
  • Microcontroller Tips
  • Power Electronic Tips
  • Sensor Tips
  • Test and Measurement Tips
  • 5G Technology World
  • Subscribe to our newsletter
  • About Us
  • Contact Us
  • Advertise

Copyright © 2025 WTWH Media LLC. All Rights Reserved. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media
Privacy Policy

Search Engineers Garage

  • Electronic Projects & Tutorials
    • Electronic Projects
      • Arduino Projects
      • AVR
      • Raspberry pi
      • ESP8266
      • BeagleBone
      • 8051 Microcontroller
      • ARM
      • PIC Microcontroller
      • STM32
    • Tutorials
      • Audio Electronics
      • Battery Management
      • Brainwave
      • Electric Vehicles
      • EMI/EMC/RFI
      • Hardware Filters
      • IoT tutorials
      • Power Tutorials
      • Python
      • Sensors
      • USB
      • VHDL
    • Circuit Design
    • Project Videos
    • Components
  • Articles
    • Tech Articles
    • Insight
    • Invention Stories
    • How to
    • What Is
  • News
    • Electronic Product News
    • Business News
    • Company/Start-up News
    • DIY Reviews
    • Guest Post
  • Forums
    • EDABoard.com
    • Electro-Tech-Online
    • EG Forum Archive
  • DigiKey Store
    • Cables, Wires
    • Connectors, Interconnect
    • Discrete
    • Electromechanical
    • Embedded Computers
    • Enclosures, Hardware, Office
    • Integrated Circuits (ICs)
    • Isolators
    • LED/Optoelectronics
    • Passive
    • Power, Circuit Protection
    • Programmers
    • RF, Wireless
    • Semiconductors
    • Sensors, Transducers
    • Test Products
    • Tools
  • Learn
    • eBooks/Tech Tips
    • Design Guides
    • Learning Center
    • Tech Toolboxes
    • Webinars & Digital Events
  • Resources
    • Digital Issues
    • EE Training Days
    • LEAP Awards
    • Podcasts
    • Webinars / Digital Events
    • White Papers
    • Engineering Diversity & Inclusion
    • DesignFast
  • Guest Post Guidelines
  • Advertise
  • Subscribe