Due to the drastic changes in technology in the last decade, so many advancements were introduced in electricity departments. The electricity bill can be paid now through E-Seva centers, ATMs, Net-banking and even through mobile phones. But prepaid electricity is a unique and new concept which saves lot of time and power for electricity department. In this system the user has to purchase an EEPROM based recharge card and it should be inserted in the slot provided on Prepaid energy meter kit.
After inserting the recharge card into the system, the user should press RECHARGE key to start recharge. Then the system will be loaded with specific units as per the recharge card value. A 16X2 LCD is provided to read units available. The system consists inbuilt prepaid energy meter which sends a pulse to the microcontroller on power consumption. The controller reads the number of pulses and deducts one unit from the recharge card for every hundred pulses.An EEPROM is provided on the board to store the updated recharge units and energy meter pulse count. This data will not be lost even in power failure cases. When the recharged units become zero on power consumption, the system shutdown all the loads connected to it.
This project uses regulated 5V, 500mA power supply. 7805 three terminal voltage regulator is used for voltage regulation. Bridge type full wave rectifier is used to rectify the ac out put of secondary of 230/12V step down transformer.
Block Diagram Description
1 1. Power Supply:-
Here we used +12V and +5V dc power supply. The main function of this block is to provide the required amount of voltage to essential circuits. +12 voltages are given. +12V is given to relay driver. To get the +5V dc power supply we have used here IC 7805, which provides the +5V dc regulated power supply.
2. EEFROM
The AT24C01A/02/04/08/16 provides 1024/2048/4096/8192/16384 bits of serial electrically erasable and programmable read-only memory (EEPROM) organized as 128/256/512/1024/2048 words of 8 bits each. The device is optimized for use in many industrial and commercial applications where low-power and low-voltage operation are essential. The AT24C01A/02/04/08/16 is available in space-saving 8-pin PDIP, 8-lead JEDEC SOIC, 8-lead MAP and 8-lead TSSOP packages and is accessed via a 2-wire serial interface.
3. LCD DISPLAY
This is the first interfacing example for the Parallel Port. We will start with something simple. This example doesn't use the Bi-directional feature found on newer ports, thus it should work with most, if not all Parallel Ports. These LCD Modules are very common these days, and are quite simple to work with, as all the logic required to run them is on board.
4. MICROCONTROLLER 8051
The device also has four 8-bit I/O ports, three 16-bit timer/event counters, a multi-source, a four-priority-level, nested interrupt structure, an enhanced UART on-chip oscillator and timing circuits. The added features of 89c51 make it a powerful microcontroller for applications that require pulse width Modulation , high-speed I/O and up/down counting capabilities such as motor control.
This block has the potential to drive the various controlled devices. In this block mainly we are using the transistor and the relays. One relay driver circuit we are using to control the light. Output signal from AT89S52 is given to the base of the transistor, which we are further energizing the particular relay. Because of this appropriate device is selected and it do its allotted function.
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