GSM Based Energy Meter Reading And Load Control | A Prepaid Energy Meter - LBM4

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Tuesday 18 May 2021

GSM Based Energy Meter Reading And Load Control | A Prepaid Energy Meter

Prepaid Energy Meter

The main objective of the project is to develop a GSM based energy meter reading system and load control through SMS. Electricity department sends employees to take meter reading every month, which is an expensive and time consuming.

The proposed project provides a convenient and efficient method to avoid this problem. The electricity department and the consumer can get the reading of the energy meter of consumers through SMS. The load can also be controlled by the use of this system through SMS using this project.

The digital energy meter that takes the reading from the energy meter is effectively interfaced with a microcontroller and display on LCD.

This GSM modem can also receive commands from the cell phone to control the owner’s electrical loads. It uses a standard digital energy meter that delivers output pulses to the microcontroller to perform counting for necessary action. On receiving command it can switch ON/OFF the Load. 

Hardware Requirements:

  3. LCD
  4. LED
  10. RELAY
  12. LAMP

Software Requirement:


Energy Meter
Energy Meter

Energy Meter:

  1. An energy or electric meter is a device that measures the amount of electrical energy consumed by a residence, business, or an electrically-powered device.
  2. Electric meters are typically calibrated in billing units, the most common one being the kilowatt hour.




  1. AT89S51
  2. It is a smaller computer
  3. Has on-chip RAM, ROM, I/O ports

Features of AT89s51:

  1. Endurance: 10,000 Write/Erase Cycles
  2. 4.0V to 5.5V Operating Range
  3. Fully Static Operating at frequency: 0 Hz to 33 MHz
  4. 128 bits Internal RAM (Data Memory)
  5. Rom 4 KB (Program memory)
  6. 32 Programmable I/O Lines
  7. Three 16-bit Timer/Counters
  8. Interrupt Recovery from Power-down Mode
  9. It contains 16 bit address buses
  10. It is 40 pin dual in package

Pin Diagram:

pin diagram of microcontroller

  1. 40 Pin IC
  2. 4 Ports
  3. 32 Programmable I/O Lines


Note: Here we are using AT89s51 instead of Arduino UNO so that we may get better understanding about actual operating the device along with we may learn about fabrication of circuit with filter(capacitor, transistor). The cost of device will also be reduced to some extent.

Power Supply:

Overal setup of power supply with circuit diagram
Power Supply

Serial Communication:

  1. Used for all long-haul communication
  2. Cables that carry serial data
  3. RS232 carries serial data in between micro controller
  4. and MODEM through DB9 connector


circuit diagram for serial communication

MAX 232


  1. The MAX232 is an integrated circuit that converts signals from an  RS-232serial port to signals suitable for use in TTL compatible digital logic circuits. 
  2. The MAX232 is a dual driver/receiver and typically converts the RX, TX, CTS and RTS signals .
  3. When a MAX232 IC receives a TTL level to convert, it changes a TTL Logic 0 to between +3 and +15V, and changes TTL Logic 1 to between -3 to -15V, and vice versa for converting from RS232 to TTL.




  1. A relay is an electrically operated switch. Many relays use an electromagnet to mechanically operate a switch, but other operating principles are also used, suchas solid-state relays.
  2. Relays are used where it is necessary to control a circuit by a low-power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be controlled by one signal.
  3. Relays with calibrated operating characteristics and sometimes multiple operating coils are used to protect electrical circuits from overload or faults

GSM Communication:

The term GSM usually means the GSM standard and protocols in the frequency spectrum around 900MHz.

Mobile Station:

The MS is the physical equipment used by a subscriber, most often a normal hand-held cellular telephone.

Base transceiver station:

The BTS comprises the radio transmission and reception devices, and also manages the signal processing related to the air interface.

GSM Module:

  1. A GSM modem is a specialized type of modem which accepts a SIM card, and operates over a subscription to a mobile operator, just like a mobile phone.
  2. From the mobile operator perspective, a GSM modem looks just like a mobile phone.
  3. When a GSM modem is connected to a computer, this allows the computer to use the GSM modem to communicate over the mobile network.
  4. While these GSM modems are most frequently used to provide mobile internet connectivity, many of them can also be used for sending and receiving SMS andMMS messages.


gsm module
GSM Module


  1. An IR LED, also known as IR transmitter, is a special purpose LED that transmits infrared rays in the range of 760 nm wavelength.
  2. The appearance is same as a common LED. Since the human eye cannot see the infrared radiations.
  3. The camera can show us the IR rays being emanated from the IR LED in a circuit.


IR Led

Display Unit:

  1. Most    common          LCDs  connected        to         the       microcontrollers          are       16x2 and 20x2 displays.
  2. This means 16 characters per line by 2 lines and 20 characters per line by 2 lines, respectively.

LCD Display
LCD Display

LCD Background:

  1. If an 8-bit data bus is used the LCD will require 11 data lines (3 control lines plus the 8 lines for the data bus)
  2. The three control lines are referred to as EN, RS, and RW
  3. EN=Enable (used to tell the LCD that you are sending it data)
  4. RS=Register Select (When RS is low (0), data is treated as a command)
  5. (When RS is High(1), data being sent is text data )
  6. R/W=Read/Write        (When RW is low (0), the data written to the LCD)
  7. (When RW is high (1), the data reading to the LCD

PIN diagram for LCD

Keil Compiler:

  1. Keil an ARM Company makes C compilers, macro assemblers, real-time kernels, debuggers, simulators, integrated environments, evaluation boards, and emulators for ARM7/ARM9/Cortex-M3, XC16x/C16x/ST10, 251, and 8051 MCU families.
  2. Compilers are programs used to convert a High Level Language to object code. Desktop compilers produce an output object code for the underlying microprocessor, but not for other microprocessors.

block diagram of energy meter reading
Block diagram of the Project


  1. By adopting this we can avoid illegal usage of current.
  2. Continuous monitoring of ac load as per our requirement either ON (or)OFF.
  3. There is not need of sending any member to come to our houses for billing.
  4. We can generate instant billing in fixed interval of time.

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