Wednesday 16 October 2013

4 DIGIT COUNT DOWN TIMER USING LCD


                   Countdown Timer Using LCD

A countdown timer is a down counter that counts from a specified time to zero. It is used in many devices such as washing machine, televisions, microwave ovens, etc. This countdown timer has three states: the running state where it counts down, the pause state where it displays the paused time and the reset state to set the countdown.

In previous post two digit count down timer was described.In this post it modified for 4 digit count down timer.I have developed this count down timer as part of my another project.This  count down timer count from 9999 to zero. This can be used as count down timer in hours or minutes or seconds by adjusting the delay value.For count down in minutes delay value will be 6000.Also the maximum value of count down can be change in program.The reset switch will reset the count down timer.Main parts of the project are microcontroller AT89C51and LCD,5v Regulated power supply.



Microcontroller AT89C51:

Microcontroller AT89C51 is at the heart of the circuit. It is a low power, high performance, 8-bit microcontroller with 4 kB of flash programmable and erasable read-only memory (PEROM) used as on-chip program memory, 128 bytes of RAM used as internal data memory, 32 individually programmable input/output (I/O) lines divided into four 8-bit ports, two 16-bit programmable timers/counters, a five-vector two-level interrupt architecture, on-chip oscillator and clock circuitry. A 11.0592MHz crystal (XTAL1) is used to provide basic clock frequency for the microcontroller. Capacitor C3 and resistor R3 form the power-on reset circuit, while push-to-on switch S20 is used for manual reset.


Liquid Crystal Display (LCD):

Liquid crystal display a type of display used in digital watches and many portable computers.LCD displays utilize two sheets of polarizing material with a liquid crystal solution between them. An electric current passed through the liquid causes the crystals to align so that light cannot pass through them. Each crystal, therefore, is like a shutter, either allowing light to pass through or blocking the light.

The liquid crystals can be manipulated through an applied electric voltage so that light is allowed to pass or is blocked. By carefully controlling where and what wavelength (color) of light is allowed to pass, the LCD monitor is able to display images. A back light provides LCD monitor’s brightness.Other advances have allowed LCD’s to greatly reduce liquid crystal cell response times. Response time is basically the amount of time it takes for a pixel to “change colors”. In reality response time is the amount of time it takes a liquid crystal cell to go from being active to inactive. Here the LCD is used at both the Transmitter as well as the receiver side. The input which we give to the microcontroller is displayed on the LCD of the transmitter side and the message sent is received at the receiver side which displays at the receiver end of the LCD and the corresponding operation is performed.

They make complicated equipment easier to operate. LCDs come in many shapes and sizes but the most common is the 16 character x 4 line display with no backlight. It requires only 11 connections – eight bits for data (which can be reduced to four if necessary) and three control lines (we have only used two here). It runs off a 5V DC supply and only needs about 1mA of current. The display contrast can be varied by changing the voltage into pin 3 of the display.

 Power Supply Unit

The power supply unit is used to provide constant 5 V dc supply to the peripherals. The 230 V ac is converted into 9 V ac by using a transformer and then a bridge rectifier rectifies it to a 9 V dc with ac ripples. This is then filtered by electrolytic capacitors used across the rectifier output. LM7805 regulator is employed to obtain a constant 5 V dc at the output.

 Count Down Timer Using LCD Program:



#include<reg51.h>
#define cmdport P3
#define dataport P2
sbit rs = cmdport^0;  //register select pin
sbit rw = cmdport^1;  // read write pin
sbit e = cmdport^6;  //enable pin
void delay(unsigned int msec)  // Function to provide time delay in msec.
{
int i,j ;
for(i=0;i<msec;i++)
for(j=0;j<1275;j++);
}
void lcdcmd(unsigned char item)  //Function to send command to LCD
{
dataport = item;
rs= 0;
rw=0;
e=1;
delay(1);
e=0;
}
void lcddata(unsigned char disp)  //Function to send data to LCD
{
dataport = disp;
rs= 1;
rw=0;
e=1;
delay(1);
e=0;
}          
void main() 
{  
  while(1)
  {
    unsigned int i,s,test_final,test_final_1,test_final_2,test_final_3,test_final_4,test_final_5;
    lcdcmd(0x38);  // for using 8-bit 2 row mode of LCD
     delay(100);
      lcdcmd(0x0E);  // turn display ON for cursor blinking
       delay(100); 
        lcdcmd(0x80);              
          delay(25);
          for(i=9959;i>0;i--)
             {    
                  lcdcmd(0x01);       
                 test_final=i;               
                 s=test_final/10000;                                                
                  if(s!=0)
                      {
                           lcddata(s+48);
                          delay(6000);
                      }
               else
                     {                            
                            s=test_final/1000;
                            test_final_1=test_final%1000;
                             test_final_2=test_final_1/100;
                             test_final_3=test_final_1%100;
                             test_final_4=test_final_3/10;
                             test_final_5=test_final_3%10;
                            lcddata(s+48);
                             lcddata(test_final_2+48);
                              lcddata(test_final_4+48);
                              lcddata(test_final_5+48);                           
                             delay(6000);
                      }                                
            }
   }
               
}       

// for 60 second delay(1 minute) == ms dealay 6000


                      

HOW CONVERT ARRAY OF ELEMENTS INTO DECIMAL VALUE



Convert Array data to an decimal number
In some programs it is necessary to convert the array elements into an integer value like receive value from keyboard and set the value as input for countdown timer.4x3 or 4x4 matrix keypads will give one key value at one time and LCD Display also display only one number at a time. So  if we need to display keyboard value 5432 you need to convert separate value of 5,4,3,2 into 5432 to set the timer. You can use this program for convert array elements to an integer.




Microcontroller AT89C51:

Microcontroller AT89C51 is at the heart of the circuit. It is a low power, high performance, 8-bit microcontroller with 4 kB of flash programmable and erasable read-only memory (PEROM) used as on-chip program memory, 128 bytes of RAM used as internal data memory, 32 individually programmable input/output (I/O) lines divided into four 8-bit ports, two 16-bit programmable timers/counters, a five-vector two-level interrupt architecture, on-chip oscillator and clock circuitry. A 11.0592MHz crystal (XTAL1) is used to provide basic clock frequency for the microcontroller. Capacitor C3 and resistor R3 form the power-on reset circuit, while push-to-on switch S20 is used for manual reset.


Liquid Crystal Display (LCD):

Liquid crystal display a type of display used in digital watches and many portable computers.LCD displays utilize two sheets of polarizing material with a liquid crystal solution between them. An electric current passed through the liquid causes the crystals to align so that light cannot pass through them. Each crystal, therefore, is like a shutter, either allowing light to pass through or blocking the light.

The liquid crystals can be manipulated through an applied electric voltage so that light is allowed to pass or is blocked. By carefully controlling where and what wavelength (color) of light is allowed to pass, the LCD monitor is able to display images. A back light provides LCD monitor’s brightness.Other advances have allowed LCD’s to greatly reduce liquid crystal cell response times. Response time is basically the amount of time it takes for a pixel to “change colors”. In reality response time is the amount of time it takes a liquid crystal cell to go from being active to inactive. Here the LCD is used at both the Transmitter as well as the receiver side. The input which we give to the microcontroller is displayed on the LCD of the transmitter side and the message sent is received at the receiver side which displays at the receiver end of the LCD and the corresponding operation is performed.

They make complicated equipment easier to operate. LCDs come in many shapes and sizes but the most common is the 16 character x 4 line display with no backlight. It requires only 11 connections – eight bits for data (which can be reduced to four if necessary) and three control lines (we have only used two here). It runs off a 5V DC supply and only needs about 1mA of current. The display contrast can be varied by changing the voltage into pin 3 of the display.

 Power Supply Unit

The power supply unit is used to provide constant 5 V dc supply to the peripherals. The 230 V ac is converted into 9 V ac by using a transformer and then a bridge rectifier rectifies it to a 9 V dc with ac ripples. This is then filtered by electrolytic capacitors used across the rectifier output. LM7805 regulator is employed to obtain a constant 5 V dc at the output.




 Convert Array data to an decimal number Program:


 #include<reg51.h>
sfr lcd_data_pin=0xA0;  // data port P2
sbit rs=P3^0; // Register select pin
sbit rw=P3^1; // Read write pin
sbit en=P3^6; // Enable pin
void delay(unsigned int msec)    //delay function
{
int i,j;                                   
for(i=0;i<msec;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(1);
en=0;
}
void lcd_data(unsigned char disp)    // function to send data on LCD
{
lcd_data_pin=disp;
en=1;
rs=1;
rw=0;
delay(1);
en=0;
}
void main()
{
 unsigned int i,s,test_final,test_final_1,test_final_2,test_final_3,test_final_4,test_final_5;
unsigned int value[4]={5,4,3,2};
while(1)
{
lcd_command(0x38);  
delay(5);
lcd_command(0x0F);      
delay(5);
lcd_command(0x80);
delay(5);
  i=value[0]*1000+value[1]*100+value[2]*10+value[3];
                  test_final=i;               
                  s=test_final/10000;                                               
                   if(s!=0)
                    {
                      lcd_data(s+48);
                       delay(250);
                    }
                   else
                     {                            
                            s=test_final/1000;
                            test_final_1=test_final%1000;
                             test_final_2=test_final_1/100  
                             test_final_3=test_final_1%100;
                              test_final_4=test_final_3/10;
                             test_final_5=test_final_3%10;
                            lcd_data(s+48);
                             lcd_data(test_final_2+48);
                               lcd_data(test_final_4+48);
                                 lcd_data(test_final_5+48);                           
                                                                  
             }                                

    }
}
                                                                       

 

HOW TO INTERFACE A 4X3 MATRIX KEYPAD TO MICROCONTROLLER 8051(AT89C51) WITH C PROGRAM


Matrix Keyboard interfacing with Micro controller 8051  


      

Keyboards and LCDs are the most widely used input/output devices of the 8051, and a basic understanding of them is essential. In this tutorial the keyboard fundamentals, along with key press and key detection mechanisms was discussed. Interfacing a keyboard with microcontroller 8051 also described here. Keypad is a widely used input device with lots of application in our everyday life. From a simple telephone to keyboard of a computer, ATM, electronic lock, etc., 

keypad is used to take input from the user for further processing. In this article we are interfacing keypad with the MCU AT89C51 and displaying the corresponding number on LCD.  This module can be further used in a number of systems to interfaced keypad with microcontroller and other processors to get desired output. The program to interface keypad with controller is written in C language which is very easy to understand. 

Keypad is organized as a matrix of switches in rows and column. The article uses a 4X3 matrix keypad and a 16x2 LCD for displaying the output of keypad. The circuit diagram shows the connection of keypad with the controller.Port P1 of the microcontroller is used to send the data for displaying on the LCD. P2^1, P2^2, P2^3 pins of microcontroller is connected to RS, RW, EN pins of LCD respectively. Port P3 is used to scan input from the keypad (refer circuit diagram for connection).


      Fig.1 Interfacing matrix keypad with microcontroller 8051

Interfacing the Keyboard to the 8051 :

        At the lowest level, keyboards are organized in a matrix of rows and columns. The CPU accesses both rows and column through ports; therefore, with two 8-bit ports, an 8*8 matrix of keys can be connected to a microprocessor. When a key pressed, a row and column make a connect; otherwise, there is no connection between row and column. In IBM PC keyboards, a single micro controller (consisting of microprocessor, RAM and EPROM, and several ports all on a single chip) takes care of software and hardware interfacing of keyboard. In such systems it is the function of programs stored in the EPROM of micro controller to scan the keys continuously, identify which one has been activated, and present it to the motherboard. In this section we look at the mechanism by which the 8051 scans and identifies the key.

Scanning and identifying the key:      
       
The following Figure shows a 4*4 matrix connected to two ports. The rows are connected to an output port and the columns are connected to an input port. If no key has been pressed, reading the input port will yield 1s for all columns since they are all connected to high (Vcc) If all the rows are grounded and a key is pressed, one of the columns will have 0 since the key pressed provides the path to ground. It is the function of the micro controller to scan the keyboard continuously to detect and identify the key pressed. How it is done is explained next.

The concept of interfacing keypad with the MCU is simple. Every number is assigned two unique parameters, i.e., row and column number (n(R, C) for example 6 (2, 3)). Hence every time a key is pressed the number is identified by detecting the row and column number of the key pressed.

Initially all the rows are set to zero by the controller and the columns are scanned to check if any key is pressed. In case no key is pressed the output of all the columns will be high. 

Whenever a key is pressed the row and column corresponding to the key will get short, resulting in the output of the corresponding column goes to go low (since we have made all the rows zero). This gives the column number of the pressed key.


Once the column number is detected, the controller set’s all the rows to high. Now one by one each row is set to zero by controller and the earlier detected column is checked if it becomes zero. The row corresponding to which the column gets zero is the row number of the digit.  


The above process is very fast and even if the switch is pressed for a very small duration of time the controller can detect the key which is pressed. The controller displays the number corresponding to the row and column on the LCD.

There are IC chips such as National Semiconductors MM74C923 that incorporate keyboard scanning and decoding all in one chip. Such chips use combinations of counters and logic gates (No micro controller).

 Keypad interfacing Embedded C Program:

#include<reg51.h>
#define port P2
#define dataport P1  // Dataport for lcd
#define sec 100
sbit rs = port^1;
sbit rw = port^2;
sbit en = port^3;

sbit col1=P3^4;
sbit col2=P3^5;
sbit col3=P3^6;
sbit row1=P3^0;
sbit row2=P3^1;
sbit row3=P3^2;
sbit row4=P3^3;
void delay(unsigned int msec) //Time delay function
{
int i,j;
for(i=0;i<msec;i++)
for(j=0;j<1275;j++);
}
void lcd_cmd(unsigned char item) //Function to send command to LCD
{
dataport = item;
en=1;
rs= 0;
rw=0;
delay(1);
en=0;

}
void lcd_data(unsigned char disp) //Funtion to send data on LCD
{
dataport = disp;
en=1;
rs= 1;
rw=0;
delay(1);
en=0;

}

lcd_string(unsigned char *disp) // Function to send string on LCD
{
int x;
for(x=0;disp[x]!=0;x++)
{
lcd_data(disp[x]);       
}
}
void lcd_ini()                  //Function to initialize the LCD
  {
    lcd_cmd(0x38);         
    delay(5);
    lcd_cmd(0x0F);       
    delay(5);
          lcd_cmd(0x01);  //clear screen
          delay(5);
    lcd_cmd(0x80);

    delay(5);
   }
void display(int a) //Display functon for LCD

{

 lcd_ini();
switch(a)
{
case 1:lcd_string("one 1");
break;
case 2:lcd_string("two 2");
break;
case 3:lcd_string("three 3");
break;
case 4:lcd_string("four 4");
break;
case 5:lcd_string("five 5");
break;
case 6:lcd_string("six 6");
break;
case 7:lcd_string("seven 7");
break;
case 8:lcd_string("eight 8");
break;
case 9:lcd_string("nine 9");
break;
case 10:lcd_string("zero 0");
break;
case 11:lcd_string("*");
break;
case 12:lcd_string("#");
break;
}
}

void check_col1() //Function for checking column one
{
row1=row2=row3=row4=1;
row1=0;
if(col1==0)           
display(1);
row1=1;
row2=0;
if(col1==0)
display(4);
row2=1;
row3=0;
if(col1==0)
display(7);
row3=1;
row4=0;
if(col1==0)
display(11);
row4=1;
}

void check_col2() //Function for checking column two
{
row1=row2=row3=row4=1;
row1=0;
if(col2==0)
display(2);
row1=1;
row2=0;
if(col2==0)
display(5);
row2=1;
row3=0;
if(col2==0)
display(8);
row3=1;
row4=0;
if(col2==0)
display(0);
row4=1;
}

void check_col3() //Function for checking column three
{
row1=row2=row3=row4=1;
row1=0;
if(col3==0)
display(3);
row1=1;
row2=0;
if(col3==0)
display(6);
row2=1;
row3=0;
if(col3==0)
display(9);
row3=1;
row4=0;
if(col3==0)
display(12);  //For #
row4=1;
}          
void keypad()
{
          row1=row2=row3=row4=0;
          if(col1==0)
          check_col1();
          if(col2==0)
          check_col2();
          if(col3==0)
          check_col3();
}

void main()
{
col1=col2=col3=1;
while(1)
{                

keypad();
 }      
}


   

Sunday 1 September 2013

NEW PROJECT TOPICS FOR ECE AND EEE STUDENTS-2013


   1.Mobile technology (GSM) based remote monitoring and control of digital Energy meter.
   2.Controlling AC lamp Dimmer through Mobile Phone (IEEE-2010).
   3.Multiple Transformers oil temperature monitoring with automatic circuit breaker operation with   SMS based alerts.
   4.A Novel Wireless Self-powered Microcontroller-based Monitoring Circuit for Photovoltaic   Panels in Grid-connected Systems (IEEE-2010).
   5.Wireless Energy Meter reading on hand-help device based on RF Transceiver.
   6. SCADA implementation based on wireless RF technology. (IEEE-2009).
   7.Method of Measuring Power Quality and Development of Monitor Device (IEEE-2010).
   8.Motor speed monitoring and control system using GSM modem.
   9.A Smart Card Based Prepaid Electricity System.
  10.High voltage fuse blown indicator with Voice based announcement system.
  11.Voice enabled devices switching for visually impaired.
  12.Industrial/power grid electrical parameter Data Acquisition system through wireless technology.
  13.DC Motors speed synchronization for rolling mills.
  14.Touch Screen based digital devices control system. This project is to build a Graphical LCD Touch Screen interface for switching electrical devices. The controlled devices can be of high voltage or low voltage.
  15.Construction of central control unit for Irrigation water pumps.  Cost effective method to control entire villagers water pumps with user level authentication. Illiterates friendly system.
  16.Wireless Energy Meter monitoring system with automatic tariff calculation.
  17.Home Network Configuring Scheme for All Electric Appliances Using ZigBee-based Integrated Remote Controller.
  18.Resistive Touch screen controlled contact less speed monitoring and controlling of dc motor with speed limit alerts.
  19.DC Motor Speed and direction control over GSM Mobile/Modem.
  20.Smart Wireless Temperature Data Logger (IEEE-2007)
  21.Energy meter monitoring and control system using SMS technology(IEEE-2007).
  22.Energy meter data logging system with Realtime clock and KWH readings. Very useful for historical data logging and analysis.
  23.Energy meter per-day average, Max and Min Load display on Graphical LCD.
  24.MMC/SD card based data logger for energy meter with time and KWH readings for historical data logging and analysis.
  25.PIR based energy conservation system for corporate Computers and lighting system.
  26.Development of Zigbee based Street Light (IEEE-2008)
  27.Wireless power theft monitoring system and indication at local substations.
  28.Touchscreen controlled lamp dimmer for next generation apartments.
  29.Wireless electrical devices monitoring and controlling system for industrial applications.
  30.Microconroller and Touchscreen controlled motor speed and direction controlling system.
  31.Touchscreen operated industrial oil dispensing system (OIL SCADA).
  32.An On-line Monitoring System of Temperature of Conductors and Fittings Based on GSM SMS and Zigbee(IEEE-2008).
  33.4-wired resistive touch screen controlled lamp dimmer for next generation apartments with Optical isolation and zero crossing detectors.
  34.Dual (active and standby) Lithium-ion battery charger for continuous non-interrupted power supply to critical loads.
  35.Graphical LCD and Touch Screen based Electrical devices control system.
  36.Implementation of wireless sensors network based industrial temperature monitoring system.
  37.Touchscreen based advanced temperature monitoring and control system with graphical LCD.
  38.GSM based Irrigation Water Pump Controller for Illiterates (No Mobile phone operation knowledge required).
  39.Triac and optically isolated diac based electrical oven temperature monitoring and controlling system with zero-crossing detector.
  40.High power LED based intelligent streetlight controlling system with automatic brightness control with vehicle presence sensor (GSM optional).
  41.Timer based Electrical Oven temperature monitoring and control for Metal Industries.
  42.GSM based SCADA implementation using Microcontroller.
  43. 3-phase irrigation water pump controller for illiterates using dual GSM Modems.
  44.Microcontroller based Substation Monitoring and control.
  45.Microcontroller based Generator/Alternator Control and Monitoring System
  46 . An On-line Monitoring System of Transmission Line Conductor De-icing(IEEE-2008).
 47.Hall Effect sensor based non-contact Tachometer for electrical motors speed measurement.
  48.Microcontroller based Single phasing preventor.
  49.IR Remote controlled Irrigation water pump controller with single phasing protection.
  50.Microcontroller based Solar Tracker with Stepper Motor Control.
  51.Auto-Credit Energy Metering System using mifare card.
  52.PWM based DC Motor Closed loop Speed Controller.
  53.Frequency Locked Loop (FLL) DC Motor Speed Control
  54.Radio Frequency (RF) based Wireless Control Of DC/Stepper Motor Speed Control.
  55.RF based Wireless Electrical Devices Controller.
  56.Motor Speed Monitoring over GSM Mobile.
  57.Microcontroller based refrigeration control system.
  58.Timer based automatic power cutoff for industrial sealing/packaging machines.
  59.High voltage fuse blown indicator with display on PC with optical isolation between PC and HV bus bars.
  60.GSM/Mobile/Cell Phone Based Device Monitoring and Control.
  61.GSM Based Automatic Irrigation Water Controller System
  62.Automatic Intelligent Plant Watering System
  63.IR (Infrared) Remote based Stepper Motor Speed and Direction Controller
  64.RC5 IR Based Remote Device Switching
  65.The Robot that follows the (Infrared) Light
  66.Frequency Locked Loop DC Motor speed monitoring and control system.
  67.Digital Tachometer (Non-contact)
  68.Digital Voltage, Current and Frequency Meter.
  69.SCADA system design and construction for real-time electrical parameter monitoring and control.
  70.Transformer oil temperature monitoring with automatic Circuit Breaker operation.
  71.GSM/Mobile/Cell Phone Based Device Monitoring and Control System.
  72.Energy Tapping Identifier Through Wireless Data Acquisition System.
  73.Substation Fuse blown Indicator.
  74.Mobile phone controlled Street Light monitoring and control system.
  75.UPS battery monitoring system over GSM for high availability systems (banking/finance/medical etc).
  76.DTMF mobile phone controlled dam water gates controlling system with high-level protection.
  77.DC Motor Speed and direction control using RF/IR/Zigbee technologies.
  78.Hazardous chemical valve control system with stepper motor and line of site remote control.
  79.Contact less Motor speed monitoring on Graphical display with high and low speed alerts.
  80.Design and construction of Earth fault relay for single phase power system.
  81.RF transceiver (Zigbee/X-Bee) based energy meter monitoring system. (Energy Meter reading on PC over wireless comm.)
  82.Talking energy (KWH) meter.
  83.Password enabled pre-paid liquid/milk dispensing system.


     
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