Reid Based Prepaid Energy Mater Essay Example

The display will also provide information on the current energy usage. The Interface software is in charge of processing and calculating the monetary value linked to energy consumption.

EMBEDDED SYSTEM:

Embedded System is a specialized combination of hardware and software designed for performing specific tasks. It is a control system driven by software, operating in real-time, and utilizing microcontrollers. These systems can function autonomously or interact with humans and networks. Embedded systems are used in various physical conditions and are sold in a competitive market that prioritizes cost-effectiveness. They should be distinguished from computer systems primarily used for processing, as well as software systems on PC or UNIX and traditional business or scientific applications. Two types of embedded systems exist: high-end and lower-end, with high-end systems typically employing 32 or 64-bit controllers and operating systems.

Lower-end embedded systems include personal digital assistants and mobile phones, which typically use 8 or 16 bit controllers with minimal operating systems and specially designed hardware layouts. Examples of such embedded systems can be found in everyday devices like washing machines and microwave ovens.

The Embedded System Design Cycle: System Design Calls

The "V Diagram" framework highlights the significance of simulation software, real-time systems, and data acquisition in dynamic test applications. Traditional testing, known as "static" testing, involves assessing component functionality by providing known inputs and measuring outputs. However, the need for faster product launches and shorter design cycles has created greater pressure to adopt more efficient testing methods.

The need for "dynamic" testing has arisen due to the testing of components while they are in use with the entire system, whether real or simulated. To minimize

cost and safety issues, it is preferred to simulate the remainder of the system using real-time hardware instead of testing components in the actual system. The diagram presented in this slide is the "V Diagram," commonly used to illustrate the development cycle. Although initially created to outline software application design processes, various versions of this diagram exist to depict different product design cycles.

The following sample diagram depicts the design cycle of embedded control applications in industries like automotive, aerospace, and defense. The diagram illustrates the sequential progression of development stages from left to right, although it's important to acknowledge that this process often involves iteration and may not strictly adhere to a linear path. The goal is to optimize this cycle by reducing the number of iterations required for a design, facilitating swift development.

When considering the x-axis as time in the diagram, the goal is to reduce development time by minimizing the "V" shape. On the y-axis, system components are evaluated at varying levels. At first, development must consider overall system requirements. As sub-systems and components are created, the process becomes more detailed and involves loading code onto individual processors. Finally, all components are combined and tested together before the entire system is ready for final production testing.

The diagram depicts the system view ranging from high-level to low-level. The V diagram symbolizes various applications derived from software development, wherein each design phase necessitates a corresponding test phase. This simplified version of the loop back/iterative process employs the X-axis to represent time. The text also highlights characteristics specific to embedded systems, emphasizing that they are computer systems concealed within non-computer products. Developing software for embedded systems

presents additional challenges compared to application development. One such challenge is effectively managing a large volume of data within a limited timeframe, known as throughput.

Furthermore, the text brings attention to various challenges and considerations associated with embedded systems. These include the necessity for swift event response, difficulties in testing embedded software, identifying and rectifying software errors without conventional user interfaces, ensuring reliable operation without human intervention, constraints imposed by limited memory space, utilization of specialized tools for program installation, power conservation in portable systems, complications arising from CPU-intensive operations, hardware cost reduction efforts and keyboards/screens/disk drives often being absent in embedded systems.

Additionally mentioned is that embedded systems typically consist of a microprocessor/microcontroller and memory components; some may possess serial ports or network connections.The relevance of these considerations is evident in various applications, particularly in the military and aerospace industries.

Industrial automation and process control software falls under the category of real-time systems, which must respond to events within a specified deadline. Any response that occurs after the deadline is considered incorrect. Real-time systems can be further divided into hard real-time systems and soft real-time systems. Hard real-time systems have strict response times, while soft real-time systems offer more flexibility but still require quick and consistent operation. Examples of hard real-time systems include nuclear power systems and cardiac pacemakers, while an example of a soft real-time system is a railway reservation system that may take a few extra seconds for data validation.

In the field of industrial automation and process control software, commonly used languages include C, C++, Java, Linux, Ada, and Assembly MPLAB features. One toolset utilized in developing embedded applications with Microchip's PIC® and dsPIC® microcontrollers

is the MPLAB Integrated Development Environment (IDE).This IDE is available for free use.

CLASSIFICATION:

• Real Time Systems.
• RTS is a system that must respond to events within a specified deadline.
• A correct response after the deadline is considered incorrect.

RTS CLASSIFICATION:

• Hard Real Time Systems

<< li  style = " text - align :  justify ; " > Soft Real Time System HARD REAL TIME SYSTEM :<<<  li  style = " text - align :  justify ; " >" Hard " real-time systems have very narrow response time . Example of Hard Real-Time System includes Nuclear power system, Cardiac pacemaker.SOFT REAL TIME SYSTEM : "Soft" real-time systems have reduced constraints on "lateness" but still must operate very quickly and repeatable.Example of Soft Real-Time System includes Railway reservation system – takes a few extra seconds where the data remains valid.LANGUAGES USED:
• C
• C++
• Java
• Linux
• Ada
• Assembly MPLAB FEATURES:MPLAB Integrated Development Environment (IDE) is a free, integrated toolset for the development of embedded applications employing Microchip's PIC® and dsPIC® microcontrollers.

MPLAB Integrated Development Environment (IDE) is a user-friendly, free toolset for creating embedded applications using Microchip's PIC® and dsPIC® microcontrollers. It is designed to run on MS Windows® as a 32-bit application and offers a range of free software components for quick application development and efficient debugging. MPLAB IDE also functions as a unified graphical user interface for various Microchip and third-party software and hardware development tools. Switching between tools is effortless, and upgrading from the software simulator to hardware debug and programming tools can be done seamlessly since MPLAB IDE maintains a

consistent user interface across all tools. MPLAB IDE features the SIM, an advanced software simulator with peripheral simulation, complex stimulus injection, and register logging capabilities for PIC and dsPIC devices.

CHAPTER 3

The RFID PREPAID energy meter's block diagram includes multiple components. Among these, the AC main Block serves as the power supply and functions at a voltage of 230V AC in a single phase. To reduce the voltage level, it is essential to connect this power supply to a step down transformer.

The transformer's output voltage is determined by its inner winding, whether it is 6V or 12V AC. This AC voltage is then converted to DC voltage using a rectifier circuit. However, the resulting DC voltage may contain ripples or harmonics. To reduce these disturbances, the rectifier's output is connected to a filter that eliminates harmonics.

This is the specific DC voltage specified. However, the controller operates at 5V DC while the relays and driver operate at 12V DC. Therefore, a regulator is required to decrease the voltage. The 7805 regulator produces 5V DC.

The voltage of 5V dc is produced by the 7805 regulator and is supplied to both the PIC microcontroller and sensors. The sensors' outputs are also connected to the PIC microcontroller. Furthermore, the controller is connected to an LCD, a keypad unit, and a SMART CARD read and write unit. The controller reads the data from the SMART CARD reader.

The controller utilizes an LCD to exhibit information. The decrease in quantity is determined by the energy consumption. Figure 3.3 presents the schematic diagram of the RFID prepaid energy meter. The description of the power supply unit's

circuit is as follows: it encompasses a step-down transformer, rectifier, input filter, regulator unit, and output filter. The purpose of the step-down transformer is to lower the voltage from the main supply (230V AC) to a more manageable level since this high voltage cannot be used directly.

The Transformer consists of two coils - the primary coil and the secondary coil, with the purpose of reducing voltage by decreasing turns in its secondary core. The output from the secondary coil is also an AC waveform, making the transformation from AC to DC crucial.

This conversion is achieved by utilizing a Rectifier Circuit/Unit, specifically designed to convert AC voltage into its corresponding DC voltage. Options for this specific function include Half-Wave, Full-Wave, and bridge Rectifiers. The diode is the key and straightforward device used in Rectifier circuits.

The diode's main purpose is to conduct electricity in a forward bias and not in a reverse bias. To establish a forward bias, the positive terminal of the diode is connected to the positive terminal of the battery, and the negative terminal is connected to its negative terminal. The most efficient circuit for this task is usually the Full wave Bridge rectifier circuit; however, it often produces output voltage with ripples. Additional circuits are employed to remove these ripples and achieve a smooth DC voltage output.

The circuit used to remove ripples and decrease harmonics from the DC voltage is known as a Filter circuit. Capacitors serve as the filter, effectively producing pure DC voltage by eliminating ripples. Moreover, these capacitors are employed to reduce the harmonics of the input voltage.

The main purpose of a capacitor is to charge and discharge. It

charges when the AC voltage is in the positive half cycle and discharges during the negative half cycle. In this case, a 1000µF capacitor is used, allowing only AC voltage to pass through while blocking DC voltage. This filter is positioned before the regulator.

Regulators maintain a steady and smooth output voltage by shielding it from fluctuations in the input AC voltage.

Furthermore, a power supply with an internal resistance above 30 ohms will negatively affect the output. Nonetheless, this problem can be successfully addressed by utilizing either low voltage or high voltage regulators. In our specific situation, we opted for 7805 positive regulators to convert the 6V dc voltage to 5V dc.

The Regulator circuit is usually followed by the Filter circuit, which commonly utilizes a Capacitor for filtering. The Capacitor's purpose is to charge and discharge. More specifically, it charges during the positive half cycle of AC voltage and discharges during the negative half cycle. Consequently, it only allows AC voltage to pass through while blocking DC voltage.

After the Regulator circuit, a filter is added to remove any ripples in the final output. A 0.1µF capacitor serves this purpose. The output voltage at this stage is 5V, which is then provided to both the Microcontroller and the sensors. Both of them need a 5V dc voltage.

The

output of the 7805 regulator is connected to the PIC 16f877A microcontroller. The microcontroller is a 40-pin IC. The first pin is the MCLR pin, which receives a 5V dc supply through a 10K? resistor. This supply is also directly connected to the 11th pin. The 12th pin of the controller is grounded.

A tank circuit is formed by connecting

a 4 MHZ crystal oscillator and two 22pf capacitors to the 13th and 14th pins of the PIC. This circuit includes the MAX-232 IC, which is a 16-pin dual in package IC. The 11th and 12th pins of the MAX-232 IC are connected to the 25th and 26th pins of the PIC microcontroller, serving as the receiver OUT and Transmitter IN pins, respectively.

The LCD is connected to pins RC0 to RD7 of the PIC microcontroller. The 13th, 14th, and 15th pins of the MAX-232 IC are connected to the smart card read Buffer. The Keypad unit is connected to pins RB0 to RB3 of the PIC microcontroller. The keypad unit comprises 4 switches: menu, exit, clear, and day increment.

The MAX-232 IC is utilized to convert the voltage from 5V to 10V and 10V to 5V. It serves the purpose of communicating with the PC and acting as a voltage converter. Additionally, an LCD is employed to display the Attendance details. The circuit obtains its input from the main source.

The main supply voltage is a single phase 230V AC voltage. However, this voltage cannot be used directly. Therefore, it needs to be stepped down. To achieve this, a Step down Transformer is utilized to decrease the voltage from 230V AC to a lower value. This is necessary because the microcontroller and sensors operate at +5V DC voltage, while the relays and drivers require +12V DC voltage. Thus, the 230V AC voltage should first be stepped down and then converted to DC.

After converting to direct current (dc), it is applied to the controller, sensors, relays, and drivers. In this project, a 230/12V step-down transformer was

utilized. For this circuit, we incorporated two regulators: a 7805 regulator for generating 5V dc and a 7812 regulator for achieving 12V dc voltage.

The output of 7805 regulator is connected to both PIC microcontroller and three sensors, while the output of 7812 regulator is connected to the driver IC and a Relay. The key components of this project include a smart card and a PIC microcontroller. The coding for the microcontroller will be programmed using a PIC Flash micro systems compiler unit. To generate clock pulses for the PIC microcontroller, a crystal oscillator is utilized. The speed of the microcontroller is determined by the value of the crystal oscillator.

In this project, we utilized a 4 MHz crystal oscillator. When a recharged smart card is presented to the reader, the data from the card is read and sent to the controller through the reader. The controller verifies if the card is old or new. If it is determined to be old, the lock to the EB power supply will be automatically opened for usage. In case an incorrect card is presented, the controller activates the alarm.

The amount will be reduced by the controller depending on the energy consumption. If it goes below zero, the controller will automatically cut down the EB power supply using the driver unit. ULN2003 is used as the driver in the driver unit to drive the 12v relay. We incorporated the process into the controller through coding, which was developed in Embedded 'C' Language.

CHAPTER 4

Hardware Requirements: 1. Power supply unit 2. Microcontroller 3. MAX-232 IC 4. LCD 5.

Keypad Unit 4. 2 POWER SUPPLY UNIT: Circuit Diagram [pic] Power

supply unit consists of following units i) Step down transformer ii) Rectifier unit iii) Input filter iv) Regulator unit v) Output filter 4. 3. 1 Stepdown transformer: The Step down Transformer is used to step down the main supply voltage from 230V AC to lower value. This 230 AC voltage cannot be used directly, thus it is stepped down.

The Transformer is comprised of primary and secondary coils. Its secondary core contains fewer turns to decrease or step down the voltage. The output from the secondary coil is also an AC waveform. As a result, converting from AC to DC is necessary. The Rectifier Circuit/Unit accomplishes this conversion.

4. 3. 2 Rectifier Unit: The Rectifier circuit uses diodes to convert AC voltage into DC voltage. Half-Wave, Full-Wave, and bridge Rectifiers are commonly used for this purpose.

The diode performs a basic function of conducting when forward biased and not conducting when in reverse bias. Forward biasing is accomplished by connecting the diode's positive terminal to the positive terminal of the battery and the negative terminal to the battery's negative terminal. The Full wave Bridge rectifier circuit is commonly used for efficient circuitry. However, the output voltage of the rectifier is in a rippled form, so additional circuits are necessary to remove the ripples from the obtained DC voltage. This type of circuit is known as a Filter circuit.

Capacitors are utilized as a filter in the input stage. Their purpose is to eliminate ripples from the DC voltage, resulting in a pure DC voltage. Additionally, these capacitors aid in reducing the harmonics of the input voltage.

The primary function of a capacitor is to charge and discharge. It charges during

the positive half cycle of an AC voltage and discharges during the negative half cycle. As a result, it only allows AC voltage to pass through and blocks DC voltage. This capacitor is placed in front of the regulator, ensuring that the output is smooth and free from ripples.

3. The 7805 Regulator unit ensures that the output voltage remains constant. It can regulate the output voltage even when there are fluctuations in the input AC voltage. As the AC voltage fluctuates, the DC voltage also changes. To prevent this, Regulators are employed.

Moreover, if the internal resistance of the power supply exceeds 30 ohms, it will negatively impact the output. However, this issue can be effectively mitigated in this scenario. The regulators are categorized into low voltage and high voltage types. Additionally, they can be further classified as follows: i) Positive regulator with the input pin, ground pin, and output pin. It is designed to regulate positive voltage.

ii) The negative regulator is connected to ground pin 2, input pin 3, and output pin. This regulator is responsible for controlling the negative voltage.
4. 3. 5 Output Filter: The Filter circuit is typically placed after the Regulator circuit. The most commonly used component for filtering is a capacitor.

The capacitor operates by charging and discharging. It charges when the AC voltage is in the positive half cycle and discharges during the negative half cycle. Therefore, it only allows AC voltage and blocks DC voltage. This filter is placed after the Regulator circuit to eliminate any potential ripples in the final output. In this context, a value of 0 is utilized.

1µF capacitor. The output at this stage is

5V and is given to the Microcontroller.
4. 4 MICRO CONTROLLER: A computer-on-a-chip is a variation of a microprocessor which combines the processor core (CPU), some memory, and I/O (input/output) lines, all on one chip.

The microcomputer, also known as a computer-on-a-chip, refers to a computer that utilizes one or more microprocessors as its CPUs. In contrast, a microcontroller can be seen as a single silicon chip containing integrated digital logic circuits, specifically designed for certain applications.

The advantages of using a microcontroller over a microprocessor are that a designer can use a microcontroller to:
1. Gather input from various sensors
2. Process this input into a set of actions
3. Use the output mechanisms on the microcontroller to do something useful
4.

MC (Microcontroller) has built-in RAM and ROM. It is cheaper compared to MP (Microprocessor) and allows for multi-machine control simultaneously. Examples of MC include 8051 (ATMEL), PIC (Microchip), Motorola (Motorola), and ARM Processor. Applications of MC include cell phones, computers, robots, and interfacing to two PCs.

4. 4. 2 Microcontroller Core Features: The microcontroller core features a high-performance RISC CPU with only 35 single word instructions to learn.

• All instructions, except program branches, take one cycle. Program branches take two cycles.
• The operating speed is DC - 20 MHz clock input and DC - 200 ns instruction cycle.
• It has up to 8K x 14 words of FLASH Program Memory, up to 368 x 8 bytes of Data Memory (RAM), and up to 256 x 8 bytes of EEPROM data memory.
• The pin out is compatible with PIC16C73B/74B/76/77.
• It has interrupt capability with up to 14 sources.
• It has an eight-level deep

hardware stack.
• It supports direct, indirect, and relative addressing modes.
• It has a Power-on Reset (POR).
• It has a Power-up Timer (PWRT) and an Oscillator Start-up Timer (OST).

The text describes the features and capabilities of the Watchdog Timer (WDT) embedded system. It includes the following: an on-chip RC oscillator for reliable operation, programmable code-protection, power saving SLEEP mode, selectable oscillator options, and utilization of low-power, high-speed CMOS FLASH/EEPROM technology.

• The design is fully static with In-Circuit Serial Programming (ICSP) capability and a single 5V In-Circuit Serial Programming feature. Additionally, it supports In-Circuit Debugging using two pins.

- Processor has the ability to read from and write to program memory.
- It can operate within a wide voltage range of 2.0V to 5.5V.
- It has a high sink/source current of 25 mA.
- Suitable for both commercial and industrial temperature ranges.

• The project utilized the PIC 16f877A microcontroller, which is part of the PIC family of microcontrollers. The PIC family consists of various series, including the 12-Series, 14-Series, 16-Series, 18-Series, and 24-Series. For this project, we specifically utilized the 16-Series PIC microcontroller.

3. The PIC microcontroller 16F877A is a 40-pin IC. The MCLR pin is the first pin of the controller, which receives a 5V dc supply through a 10K? resistor. The 11th pin also directly receives this supply, while the 12th pin is grounded.

A tank circuit comprising of a 4 MHZ crystal oscillator and two 22pf capacitors is connected to the 13th and 14th pins of the PIC microcontroller.

The PIC microcontroller 16F877A possesses the following features:
- Operating frequency: DC-20Mhz.
- Flash program memory (14 bit words):8K.
- Data memory (in bytes): 368.
- EEPROM

Data memory (in bytes):256.
- Interrupts: 15.
- I/o ports: A, B, C, D, E.
- Timers: 3.
- Analog comparators: 2.
- Instructions: 35.

3. 3 pin diagram for pic 16f874a/877a: [pic]

4. 4 functional block diagram for pic 16f877a: [pic]

4. 4 LCD Display: Liquid crystal display (LCD) is composed of material that possesses properties of both liquid and crystals.

Within a certain temperature range, the molecules in LCD displays behave similarly to those in a liquid, but they are arranged in a crystal-like structure. The display technology used in microcontroller devices is increasingly incorporating "smart LCD" displays to provide visual information. In this discussion, we will explore how to connect a Hitachi LCD display to a PIC microcontroller. Hitachi LCD displays, which utilize the LCD HD44780 module, are affordable and easy to use. Furthermore, they offer the capability of presenting information using the 8 x 80 pixels available on the display. Additionally, Hitachi LCD displays come with a standard set of ASCII characters as well as Japanese, Greek, and mathematical symbols.

For a data bus of 8 bits, the display needs a +5V supply and 11 I/O lines. However, for a 4-bit data bus, only the supply lines and seven additional lines are required. When the LCD display is not enabled, the data lines are in a tri-state, which means they are in a high impedance state, similar to being disconnected. This ensures that they do not interfere with the microcontroller's operation when the display is not being addressed. The LCD also needs 3 "control" lines from the microcontroller, namely Enable (E), R/W, and RS lines.

When the (E) line is low, the LCD is disabled and ignores signals from R/W and

RS. When the (E) line is high, the LCD checks the state of the two control lines and responds accordingly. The Read/Write (R/W) line determines the direction of data between the LCD and microcontroller. When it is low, data is written to the LCD. When it is high, data is read from the LCD.

|Register select (RS) |The LCD uses this line to interpret the type of data on the data lines. If it is low, an instruction is being written, and if it is high, a character is being written.| Logic status on control lines: E     0 disables access to the LCD, 1 enables access to the LCD. R/W 0 indicates writing data to the LCD, and 1 indicates reading data from the LCD. RS    0 represents an instruction, and 1 represents a character. Writing data to the LCD involves several steps: setting the R/W bit to low, setting the RS bit to logic 0 or 1 (depending on whether it is an instruction or character), setting the data on the data lines (if writing), setting the E line to high, and then setting the E line to low. Reading data from the LCD follows the same steps, but the control line R/W must be high. When a high signal is sent to the LCD, it will reset and wait for instructions.|

Instructions often sent to an LCD display after a reset include turning on the display, turning on a cursor, and writing characters from left to right. After initialization, the LCD is prepared to receive additional data or instructions. If a character is received, it will be written on the display and move the cursor

to the right. The Cursor denotes the next position for writing a character. To write a string of characters, we must first establish the starting address and then transmit each character individually.

The display of characters is stored in the data display (DD) RAM, which has a size of 80 bytes. The LCD display also has 64 bytes of Character-Generator (CG) RAM, which is used for user-defined characters.

The data in CG RAM is represented as an 8-bit character bit-map. Each character occupies 8 bytes of CG RAM, allowing the user to define a total of eight characters. To display the character bit-map on the LCD display, we first need to set the CG RAM address to its starting point (usually 0) and then write data to the display. The picture provides the definition of a 'special' character.

Before accessing DD RAM to define a special character, the program needs to set the DD RAM address.

The process of writing and reading data from LCD memory occurs from the last address set up using the set-address instruction. When the address of the DD RAM is set, a newly written character will be displayed in the correct position on the screen. Up until now, we have been discussing the writing and reading operation for an LCD as if it were a regular memory. However, this is not the case.

The LCD controller requires a time range of 40 to 120 microseconds (uS) for writing and reading, while other operations may take up to 5 mS. During this period, the microcontroller is unable to access the LCD, making it necessary for the program to be aware of when the

LCD is busy. There are two approaches to address this issue. One approach involves checking the BUSY bit present on the data line D7. However, this method is not ideal as LCDs can become stuck, leading the program to remain indefinitely in a loop continuously checking the BUSY bit.

The LCD can be delayed to allow it to finish an operation. Refer to the previous table for instructions on writing to and reading from the LCD memory. Initially, it was stated that 11 I/O lines were required for LCD communication, but a 4-bit data bus can suffice.

Thus, we can reduce the total number of communication lines to seven. The diagram below shows the wiring for connection via a 4-bit data bus. In this example, we use an LCD display with 2x16 characters labeled LM16X212 by Japanese maker SHARP. The first row displays the message 'character' along with two special characters '~' and '}'. The second row shows the word 'mikroElektronika'. The article titled "INTERFACING PIC MICROCONTROLLER TO LCD" provides more information. [pic] 4.

5 DESIGN OF EMBEDDED SYSTEM. Embedded systems follow a similar design cycle as other system development processes. The flow of the system is as follows:

• In the initial phase of the project, design considerations such as software and hardware components, sensors, and input/output are taken into account.
• The electronics component typically consists of either a microprocessor or a microcontroller.
• In certain cases, large or outdated systems may use general-purpose mainframe computers or minicomputers.

User Interfaces: Embedded systems have diverse user interfaces that require special consideration. The user interface is crucial for an embedded module as it allows the user to conveniently

check the output. A commonly used interface in embedded systems employs two buttons (at minimum) to navigate a menu system (specifically, one button is used to move to the next menu entry while the other button is used to select a menu entry). Additionally, it is common practice to reduce and simplify the type of output. Some designs opt for a status light for each interface p