Monitoring System using AT89C51

Introduction to Monitoring System using AT89C51: Intercoms and calling bells fit properly only in the luxurious hotels, lodges, and high-class buildings. In small vicinities like small hotels, offices, and clinics, these are not the correct options to choose for communication between the working/assisting staff and people. It is all because of the cost and the fact that this provision can be made for a limited number of points. Here’s a simple and economical room-monitoring system that provides audio-visual identification of the call point. In addition to this, the system also provides feedback to the caller (in the form of a busy signal). Using minimal hardware and software, this project offers a clean and easy way to communicate.

Circuit Description of Monitoring System using At89c51

From the circuit diagram, it is clear that the heart of the circuit is microcontroller IC AT89C51 (IC1) which is usually the common component when we talk about microcontroller-based projects. In this particular project, two ports: 0 and 2 of the microcontroller are used in output mode for the seven-segment display and LEDs. Similarly, port 1 is set in input mode to receive input signals from the switches. The overall configuration is depicted clearly in the figure below.

monitoring system using at89c51

 

Seven-segment display, switches, few LEDs, piezo-buzzer, and passive components are the key elements of this circuit along with the IC. Once the connection is set up, the circuit is ready for installment. In doing so, one must fix the switches and their respective LEDs in eight different rooms enabling the person to make a request when the system is not busy responding to another request.

And, the remaining circuit is set up in the control room where the request is received and responded to. Pull-up resistors R1-R8 are connected across the switches and current-limiting resistors R10-R17 are fixed next to corresponding LEDs to protect circuit components from electrical hazards. A few more components are connected to the microcontroller pins 9,19 18 and 31 for reset and clocking purposes as shown in the circuit diagram.

Once an individual presses the switch, the call-point number corresponding to that switch is displayed on the seven-segment display DIS1 (LTS542) which is configured in common-anode mode since this display is interfaced to port 0 of the microcontroller. And, then the piezo-buzzer connected to the port pin 0.0 sounds indicating that a request is being made.

The display and buzzer keep on displaying and sounding for certain intervals as programmed in the IC. To avoid system failure during this particular interval when the system is busy responding to one request and if one or more request is being made, all the eight LEDs are left blinking to indicate the situation. Hence, an individual gets notified and waits until the LED stops blinking. Now, when the blinking stops, any person can ask for help with the controller and press the switch. When the controller responds to the request, the blinking process continues to avoid system interruption.

The software section of this project is simplified with the use of assembly language in programming the microcontroller (source code is attached at the end). As a result, more people can understand and implement the project.   The source code for programming is attached at the end along with a table that constitutes codes to generate a seven-segment display and corresponding RAM locations of the microcontroller to store the codes.

 

PARTS LIST OF MONITORING SYSTEM USING AT89C51 MICROCONTROLLR

Resistor (all ¼-watt, ± 5% Carbon)
R1 – R8, R9 = 10KΩ
R10 – R17 = 470 Ω
R18 = 150 Ω
Capacitors
C1 = 10µF/16V (Electrolytic Capacitor)
C2, C3 = 33 pF (Ceramic Disc)
Semiconductors
IC1 = AT89C51 (Microcontroller)
LED1 – LED8 = Red LED
DIS1 = LT542 Common Anode Display
Miscellaneous
SW1 – SW8 = Push-to-on Switch
XTAL1 = 11.0592 MHz Crystal
PZ1 = Piezo-buzzer

Check out other interesting projects using AT89C51 posted in bestengineeringprojects.com

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  2. Microcontroller AT89C51 based Metro Train Prototype
  3. AC Motor Speed Controller Circuit Using AT89C51
  4. DIY Soccer Substitution Board using AT89C51

Software for Monitoring System using AT89C51:-

Talking about the software design section, it is much simpler since the entire program can be coded using any text editor application. However, it needs to be saved as an ‘MS.ASM’ file. To work with the project, we should generate the HEX file; MS.HEX with the help of ASM51.EXE assembler.

For simplicity, the steps of the Monitoring System using AT89C51 are summarized below:-

  • Using AT and C51 programmer, program the microcontroller with the MS.HEX file generated.
  • Once programming is successful, extract the microcontroller carefully from the programmer kit and fix it on the IC base of the circuit PCB.
  • When the above steps are implemented, assemble and solder the entire circuit components on the PCB and connect a 5 VDC external power supply to start circuit operation.
  • On pressing a switch, the respective call-point number is displayed on the display and all LEDs start blinking, also the buzzer starts sounding for the time interval as programmed.
  • If the project doesn’t work as prescribed in the steps above, then check all the connections and verify the program and repeat the steps. And, if it works properly, install the circuit. The eight switches and respective LEDs are fixed at different call points where required. Similarly, the remaining circuit with a seven-segment display and buzzer must be placed in the control room. Codes for Display Generation Along with RAM Location for Their Storage

     

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