GROUP8

SCHOOL OF ELECTRICAL, ELECTRONIC AND COMPUTER ENGINEERING

ENERGY METERGROUP 8

Document Type : Phase 3 Report, Electrical Design 4 Project

Authors Name : Euveshen Govender 206509534

Shaprin Pillay 205514551

Jared Kisten 206500555

Project Supervisor : Mr. Narushan Pillay

Due Date : October 25, 2010

Electrical Design 4

Energy Meter

Abstract.This report describes the approach and processes used to develop a final design of a system capable of measuring real power from the mains. A description of communication between the MCP3909 and microcontroller is implemented in the report using the method of serial peripheral interface (SPI).The MCP3909 will be transmitting values of voltage and current to the microcontroller in the form of a 32 bit number and using these values of current and voltage we are able to calculate the power and this is displayed both on the computer and LCD. The report contains hardware schematics, simulation results and software.

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ContentsAbstract.................................................................................................................................................... ii

1. Introduction......................................................................................................................................1

2. Project Description..........................................................................................................................2

2.1. Overview..................................................................................................................................2

2.2. Features....................................................................................................................................2

3. Hardware Design.............................................................................................................................3

3.1. PCB – POWER SUPPLY........................................................................................................3

3.2. PCB Design..............................................................................................................................4

4. Software Design...............................................................................................................................6

4.1. Interface 3: LCD display configuration and circuitry..............................................................6

Configuring the LCD Display:........................................................................................................6

Data Transmission...........................................................................................................................7

4.2. Interface 2................................................................................................................................7

Serial Peripheral Interface (SPI) - Data Transmission.....................................................................7

4.3. Interface 4: Communication between Microcontroller and Computer....................................9

RS-232 Communication:.................................................................................................................9

Level conversion:.............................................................................................................................9

Data transmission via RS-232 port:...............................................................................................10

4.4. Choosing a Microcontroller...................................................................................................11

5. Microcontroller pseudo Code:.......................................................................................................12

Program Overview.........................................................................................................................15

Visual basic Software design...........................................................................................................16

6. Testing & Results...........................................................................................................................22

7.1. Full schematic & setup...................................................................................................................22

7. Management...................................................................................................................................25

Work distribution between group members:.....................................................................................25

Current Status....................................................................................................................................25

Timeline.............................................................................................................................................25

8. Conclusion.....................................................................................................................................26

References..............................................................................................................................................27

Appendix...............................................................................................................................................A1

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1. Introduction

A final design of an energy meter is presented in this report. It was required to create a system interface to a computer on one side, and mains on the other. The circuit is capable of measuring power; this is done by multiplying the measured values of voltage and current. The power is to be displayed on an LCD panel, we used the LMB162ABC which is manufactured by - topward - 2 line 16 character. We had the option of transmitting data to the computer via RS-232 or USB, we chose the RS-232 as we were more familiar with it and it is inexpensive, and it only requires four capacitors for its connection. The circuit is simple and consists of the MCP3909 measurement unit; we also use a transformer to step down the high voltages from the mains to a suitable voltage that the MCP3909 could handle. We not only needed to display values of power on the computer but had to create an application on the computer that reports and logs power reading.

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2. Project Description

2.1. Overview

The purpose of this project is to measure power from the mains 230Vrms, 50Hz supply. The dangerously high mains supply is stepped down appropriately using a transformer in order to make use of the measuring IC, the MCP3909. Power is obtained through the MCP3909 taking in analogue input signals for both voltage and current measurements. The voltage and power values are now sent to the microcontroller via SPI. It is here in the microcontroller were the power value is determined (voltage*current*gain). From the microcontroller we display the power value on an LCD via GPIO. The power value is sent to the PC through serial communications. This makes use of the RS232 cable to send data serially to the computer. A VB interface is used to display the value on the PC.

2.2. Features

Power supplied via the mains(230 stepped down to 5V) LCD screen user interface – LCD screen used to display the power Hardware circuitry IC- MCP3909 (energy meter) PC interface

Figure 1: Overview Block Diagram

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3. Hardware Design

3.1. PCB – POWER SUPPLY

Figure 2: Track layout with relevant pin connections

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Figure 3: Top 3-D view of power supply

3.2. PCB Design

Figure4 : Component layout on ultiboard

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Figure 5: Track layout with relevant pin connections

Figure6 : Top 3-D view of PCB

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Figure 7: Bottom 3-D view showing surface mounting of the MCP3909

Two additional connections were necessary to make the PCB work. Pin 9(Master Clear pin) of the MCP3909 is connected to Port B pin 3 of the Atmega 16. This is used in order to enable the SPI for communication. Also, Pin 14 (Chip Select) of the MCP3909 is connected to ground as this pin needs to be a low when serial communication takes place.

4. Software Design

4.1. Interface 3: LCD display configuration and circuitry

Configuring the LCD Display:The LCD display has two primary modes of operation, 8-bit mode and 4-bit mode. 8-bit mode is used when speed is important and this mode requires ten I/O pins from the microcontroller. 4-bit mode requires only 6 I/O pins and is used when trying to minimize the amount I/O pins required in a design. To minimize I/O pin requirements 4-bit mode will be used for this design. Since 4-bit mode only uses four data pins, data is transferred four bits at a time. Only the last four data bits of the LCD display are used.

Table 2: Electrical characteristics of LCD Display [5]

Parameter Symbol RatingOperating voltage VDD 4.7 – 5.3VInput voltage VI 0.8VDD – VDD

Operating current IDD 1.3 – 3.0mA

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Figure 8: LCD Display hardware configuration

Figure 15 shows the necessary connections for the LCD module. Pins 1 and 2 are the power supply pins. The R/W pin (Pin 5) requires a LOW signal for writing to the LCD display and a HIGH signal to read from it. Pin 4 is the register select pin used to select whether display data or instruction data is being sent and pin 6 is the enable pin. Pins 7 to 14 are the data pins with pin 14 being the most significant bit.

Data TransmissionAll data transmitted to the LCD needs to be characters for transmission to work. Using the predefined function on C,” lcd_putf()”, this displays the value on the LCD display. Since we are using 4 bit mode, the first 4 bits from the MSB side (i.e. bit 7 to4) will first be transmitted then the next 4.

4.2. Interface 2

Serial Peripheral Interface (SPI) - Data Transmission

10

1 0 0 1 1 0 1 1

Shift DirectionLSBMSB

SCK

SCK

CS

SS

MASTER

MOSI MISO

Clock Generator

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Figure9: Master and Slave interconnection

The SPI master and slave interconnection diagram shown above explains how the shift register is used to transfer and receive the data.The master transfers0b10011011 (0×9B) to the slave and at the same time the slave device also want to transfer the 0b01001100 (0×4C) data to the master.By activating the CS (chip select) pin on the slave device, now the slave is ready to receive the data.On the first clock cycle both master and slave shift register will shift their registers content one bit to the left, the SPI slave will receive the first bit from the master on its LSB register while at the same time the SPI master will receive its first data from slave on its LSB register.

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0 1 0 0 1 1 0 0

Shift DirectionLSBMSB

SLAVE

SO SI

LSB

MSB

MSB

MSB

MSB

MSB

MSB

MSB

MSB

MSB

MSB

Slave

LSB

LSB

LSB

LSB

LSB

LSB

LSB

LSB

LSB

LSB

LSB

1st Clock

2nd Clock

3rd Clock

5th Clock

1 0 0 1 1 0 1 1 0 1 0 0 1 1 0 0

1 0 0 1 1 0 0 1 0 0 1 1 0 1 1 0

0 1 1 0 1 1 0 1 0 0 1 1 0 0 1 0

1 1 0 1 1 0 1 0 0 1 1 0 0 1 0 0

1 0 1 1 0 1 0 0 1 1 0 0 1 0 0 1

0 1 1 0 1 0 0 1 1 0 0 1 0 0 1 1

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Figure 10: Master and Slave Data Transfer Diagram

Using the same principal for each bit, the complete data transfer between master and slave will be done in 8 clock cycles. Once the complete transfer is done, the contents of the shift register are sent to the buffer register. Data can now be read from the buffer register. It is very important to read the incoming data as it will be lost in the next transfer of data. For the purpose of this design, only data transfer from the master to slave (MCP3909 to MCU) will take place as we only need the current and voltage values from the MCP3909.

4.3. Interface 4: Communication between Microcontroller and Computer

RS-232 Communication:The RS-232 is an asynchronous serial communications port. Data is transmitted by the RS-232 port, one bit at a time (serially transmitted). The RS-232 contains two data lines, the TX and RX lines. The TX is a wire which allows the transmission of data to the next device, and the RX is the wire which receives the data from the other device. For the purpose of the design, we will only be using the TX pin, as data will only be sent to the computer.

Figure 11: Serial data transmission between two devices

The logic levels of the RS-232 port is defined as follows, HIGH = -12V and LOW = 12V, while on a microcontroller the logic levels are defined as HIGH = 5V and LOW = 0V. Therefore a level converter is required to interface the computer to the microcontroller to obtain the correct logic level.

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MSB

MSB

MSB

LSB

LSB

LSB

LSB

LSB

LSB

6th Clock

8th Clock

1 1 0 1 0 0 1 1 0 0 1 0 0 1 1 0

1 0 1 0 0 1 1 0 0 1 0 0 1 1 0 1

0 1 0 0 1 1 0 0 1 0 0 1 1 0 1 1

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Level conversion:To obtain the desired voltage levels (+5V high, 0V low), the MAX232 chip is used. This device connects to the USART terminals of the microcontroller and directly to the RS232 port. The MAX232 requires 4 capacitors to ensure that it operates correctly.

Fig 12: Pin connection of MAX 232 interfaced with both the Microcontroller and DSUB9F, connector for the RS-232 cable.

Data transmission via RS-232 port:Data is transferred one bit at a time (serial communication). Before data transmissions can occur, some properties needs to be specified. Such properties are; baud rate, number of data bits, number of start bits, number of stop bits, and type of parity is to be used (even, odd, or no parity).

In idle mode the RX pin of the RS-232 port remains low, to start transmitting data a low (12 V for RS-232) start bit is sent on the pin the PC detects this change in state, to test if this is a start of data transmission the PC checks the state of the pin at half the time it takes to transfer one bit, if the state is still low, then the PC consider it as a start bit and does not neglect it as noise. Thereafter the first bit is transmitted, after all bits have a parity bit is sent (if parity is in use), followed by one or two stop bits (stop bits denoted by a high state, -12 V for RS-232).

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Figure 13: Example of Data Transmission (8 bits, no parity, and 1 stop bit)

4.4. Choosing a MicrocontrollerThe microcontroller used must be able to firstly accommodate all of the required inputs and outputs. The following figure shows the required number of inputs and outputs.

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Enable

SCK SD0

LCD DisplayInputs (SPI)

D4D5D6D7

Register Select

Microcontroller

Computer Display (USART) 9((USART TX

Read/ write

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Figure 14: Microcontroller I/O Pins Required

From this diagram it can be seen that 10 I/O pins are required. Other microcontroller features required by this design are shown in the table below.

Table 3: Microcontroller Requirements

Feature RequirementTimer YesADC NoSPI YesUSART YesMemory No

It was therefore decided that a 32 pin microcontroller would be sufficient for this project. The ATmega 16 or the ATmega32can be used for this project. We will be using the ATmega 16. It was chosen because it can accommodate all the inputs and outputs required and it is fairly cheap compared to other 32 pin microcontrollers.

5. Microcontroller pseudo Code:The current and voltage from the mains are measured using the appropriate analogue circuitry and the MCP3909 IC. It is this chip that sends the obtained voltage and current values to the microcontroller via a SPI (Serial Peripheral Interface) connection. The microcontroller handles the incoming data as described by the following algorithms:

Main Loop:

The microcontroller waits for the data from the MCP3909 IC. If the data received counter equals one then the microcontroller exits the main loop and

breaks to the Calculation subroutine. Else if the data counter is not equal to one then the microcontroller code continues to loop in

the main program

SPI Data Received Interrupt:

Move receive data to temp register Set data receive count to one

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Exit interrupt

Calculation Subroutine:

Clear the data received counter Set voltage register equals the higher 16-bits of the temp register Set current register equals the lower 16-bits of the temp register Multiply the current value with the stored value in the voltage register, and store the result in

the power register Multiply the contents of the power register by the gain factor (factor by which the voltage and

current was scaled), the accurately determine the power. Store this result into the power register.

Call the ASCII Conversion subroutine. Call the LCD Display Subroutine Return back to main program

ASCII Conversion Subroutine:

The following algorithm is designed to handle values up to 9999, but can be adapted to handle higher values

Take voltage value Loop while value is greater than a thousand, subtract one thousand and increment thousand

register. Break to next step if value less than thousand. Loop while value is greater than a hundred, subtract one hundred and increment hundred

register. Break to next step if value less than hundred. Loop while value is greater than ten, subtract ten and increment ten register. Break to next

step if value less than ten. Loop while value is greater than zero, subtract one and increment unit register. Break to next

step if value is equal to zero. Add offset value to the thousand, hundred, ten and unit register Call transmit subroutine Clear thousand, hundred, ten and unit register Repeat above steps for current value After both values are sent, exit subroutine

Transmit Subroutine:

Send the thousand register value via the RS232 port Wait for transmit complete interrupt flag to be set Send the hundred register value via the RS232 port Wait for transmit complete interrupt flag to be set Send the ten register value via the RS232 port Wait for transmit complete interrupt flag to be set Send the unit register value via the RS232 port Wait for transmit complete interrupt flag to be set Return from subroutine

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LCD Display subroutine:

Clear LCD Using standard library available in all C compilers, it is possible to convert the values we are

receiving into a character string which can be displayed on an LCD Display string on LCD, using predefined function “lcd_putsf()”

Visual Basic pseudo Code:

Visual Basic interface is used to display the value of power, voltage, current and error in measured value. The resulting values are also stored in a text document for future access. The algorithm for the Visual Basic Pro is described below.

Visual Basic Code:

Main program:

Wait for received data When data received, break to Received Data subroutine If both values are received( complete counter is one), jump to Calculate subroutine

Received Data:

Check Variable select (Variable select is a counter used to specify which variable is received i.e. Voltage or current.)

If Variable select is equal to one (all values received will be stored in the voltage variable)o Check Received Counter

o Case1: Received Counter is equal to one, multiply the received data by a thousand

and add it to the voltage variableo Case2: received counter is equal to two, then multiply the received data by hundred

and add it to the voltage variableo Case3: received counter is equal to three, then multiply the received data by ten and

add it to the voltage variableo Case4: received counter is equal to four; add received data to the voltage variable.

o Clear received counter and increment the variable select

Else If variable select equals two o Check Received Counter

o Case1: Received Counter is equal to one, multiply the received data by a thousand

and add it to the current variable.

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o Case2: received counter is equal to two, then multiply the received data by hundred

and add it to the current variable.o Case3: received counter is equal to three, then multiply the received data by ten and

add it to the current variable.o Case4: received counter is equal to four; add received data to the current variable.

o Clear received counter and set variable select to one. Set complete counter to one.

Exit subroutine.

Calculate subroutine:

Multiply the current, voltage and gain (value which were used to scale voltage and current variables) and store result in power variable.

Display voltage, current and power, using text boxes. Store voltage, current and power in a text file Return to main loop.

Program Overview

The main program loops continuously until the data is received via the SPI which triggers a,receive complete interrupt. The data comes in as a 32 bit value in the interrupt service routine the value is stored in a temporary register. The data received register indicates weather you receive the value. If the data received is equal to one it will break away from the main program into the calculation subroutine. In the calculate subroutine we set the higher 16bits of the temp register as voltage and the lower 16bits as current. The power is calculated by multiplying the current, voltage and gain. Once current and voltage values have been obtained, we use our ASCII subroutine to convert the values into equivalent ASCII values. Transmit the resultant current and voltage values via RS232. Display the calculated power value on the LCD. In order to do this we need to convert the power value into a string, then only can we display the values using predefined functions” lcd_putsf ()”.

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After the data is sent the visual basic program stores the received voltage and current values as described in procedures above. The power value is calculated. Display the voltage, current and power values using the graphical user interface shown below, and also stores these values in a text file.

Visual basic Software designThe first question that needs to be asked when approaching the software design is what we want the software to do. In this design the software has two important functions. The first function is to send and receive data using serial communication. The second and most important function is to capture the data and store in a database so that it can be analyzed by the user. These functions will be broken down into further detail following the report.

The basic software functions that are required from Visual Basic can be seen in figure16. Once the user opens the form on visual basic, the software starts working automatically. This means that the serial port is opened and then waits until data is received. When data is received, the ASCII values are automatically converted by visual basic. These decimal number and stored in a temporary variables. These decimal numbers are then added up to form a decimal number of two decimal points which is then ready to be sent to Microsoft Access. An example of how the numbers are received and converted is illustrated in the following table.

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Visual basic program:

Firstly, variables needed to be defined as strings, integers or bytes respectively. We then needed to create a data base in Microsoft Access and then export it visual basic using DataGridView. Two buttons were created on visual basic to allow the user to perform various functions. An exit button was created to allow user to exit from interface and a refresh button was used to receive current, voltage and power values and are displayed with the aid of textboxes. The received values from serialport1 were ASCII values which were transmitted from the microcontroller and we used the ReadChar() function to handle this. When programing this button, the serial port 1 was set up, time and date, using DateTimePicker1.Text as well as logging data into the database created using Microsoft access.

Error handling:

It was necessary to create an error handler in the textboxes which only allowed numeric values to be displayed in textboxes, such as “0123456789”.

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Fig.15 Flow chart of visual basic code

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Figure 16: Graphical user interface using visual basic

Visual basic code:

Flow diagrams Public Class Form1 Dim hr As Integer Dim power As Integer Dim current As Integer Dim voltage As Integer Dim min As String Dim time As String Dim time_1 As String Dim millisecond As String Dim num As Byte Dim CharsAllowed As String Dim MyDataRow As DataRow

Private Sub form1_load(ByVal sender As System.Object, ByVal e As System .EventArgs)handles MyBase.Load(http://dotnetperls.com/datagridview-vbnet) Me.Design4TableAdapter.Fill(Me.Database1DataSet.Design4) Dim con As New OleDb.OleDbConnection

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con.ConnectionString = "provider=provider=microsoft.ACE.OLEDB.12.0;data" Design4BindingSource = |DataDirectory|\design_4.accdb" Me.Design4TableAdapter.Fill(Me.Database1DataSet.Design4) End Sub Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)

End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click End End Sub

Private Sub TextBox4_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox4.KeyPress CharsAllowed = "0123456789" If CharsAllowed.IndexOf(e.KeyChar) = -1 Then e.Handled = True End If End Sub

Private Sub TextBox4_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox4.TextChanged

End Sub

Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click TextBox2.Text = "" TextBox3.Text = "" TextBox4.Text = "" SerialPort1.PortName = "COM1" SerialPort1.BaudRate = 9600 SerialPort1.DataBits = 8 SerialPort1.StopBits = IO.Ports.StopBits.One SerialPort1.Parity = IO.Ports.Parity.None SerialPort1.Open() power = SerialPort1.ReadChar() + 48 SerialPort1.Close() SerialPort1.Open() voltage = SerialPort1.ReadChar() + 48 SerialPort1.Close() SerialPort1.Open() current = SerialPort1.ReadChar() + 48 SerialPort1.Close() Dim MyDataRow As DataRow MyDataRow = Database1DataSet.Tables("design_4").NewRow() MyDataRow("power") = TextBox4.Text MyDataRow("voltage") = TextBox3.Text MyDataRow("current") = TextBox2.Text MyDataRow("Date") = DateTimePicker1.Text hr = DateTimePicker1.Value.Hour.ToString() min = DateTimePicker1.Value.Minute.ToString() time = hr & ":" & min MyDataRow("time") = time TextBox1.Text = time

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Database1DataSet.Tables("design_4").Rows.Add(MyDataRow) Me.Validate() Me.Design4BindingSource.EndEdit() Me.Design4TableAdapter.Update(Me.Database1DataSet.Design4) TextBox4.Text = power TextBox3.Text = voltage TextBox2.Text = current End Sub



End Sub



End Sub

Private Sub Label2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label2.Click

End Sub

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6. Testing & Results

7.1. Full schematic & setup

Now that all the paper design is complete the actual building and testing of both the hardware and software designs had to be implemented.

After testing this circuit, there was an error that occurred. At first there was no communication taking place between the PC and the microcontroller. The first step in debugging was to look at the device that allows communication to take place. This was the MAX232. After looking at all the connections for the MAX232 it was found that no errors were present. This left the microcontroller. After researching it was noted that the microcontroller runs of an internal clock of 1MHz by default if not changed. This frequency is too low for serial communication to work. Now that the problem was recognized the solution was to change the internal clock of the microcontroller to 4 MHz by fusing the bits using CodeVisionAVR C Compiler. After this was done the circuit worked and all that was left to do was to design a PCB (printed circuit board) for the final prototype. This PCB was designed using Ultiboard from the Electronics Workbench software package ( as seen in section 3 hardware design). The actual PCB’s as well as the final system overview is illustrated below :-

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The step down transformer steps down the high mains voltage from 230 V AC to 8 V AC. We then created a power supply using simple analogue circuitry. The 8 V AC going into the supply is converted to DC voltage using a full wave bridge rectifier & making use of a smoothing capacitor to give a smooth DC output with very little ripple. The inexpensive Lm7805 voltage regulator is used to give a constant 5V DC output at 1 Amp.

The 5V DC is sent to the main PCB circuit to power the MCP3909, the Atmega 16 and the LCD. A function generator is used to provide inputs to pins 5, 6, 7 & 8 of the MCP3909.

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7. Management

Work distribution between group members:

Jared Kisten – power supply, SPI

Euveshen Govender – microcontroller, LCD display, SPI, serial communications

Shaprin Pillay –visual basic interface.

Current StatusAt the time of writing, the following progress has been made:

Final specifications Complete Design layout Complete software structure

TimelineThe following figure shows a projected timeline.

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8. Conclusion

The aim of this design was to develop an Energy Meter which allowed a user to monitor data from the mains and also log these values into a data base. This takes out the possibility of human error. The background theory was properly researched and a time schedule was drawn up to make this design a success within the time period given. Problems presented themselves during this design but research and innovative thinking made this project possible. The full paper design of this project was presented in this report, describing the features and functionality of the energy meter. The hardware schematics were designed and simulated using Simulink and Ultiboard. The software described in this report is implemented and simulated and then integrated with the hardware for testing.

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References

[1] Mobicon Electronic Components. 2002. Ultrasonic Sensor. (Transmitter) http://www.mantech.co.za/Datasheets/Products/UT1612MPR.pdf, accessed on March 5, 2010.

[2] http://www.kpsec.freeuk.com/powersup.htm#trsr , accessed on August 20, 2010

[3] Wikipedia, “Sound Pressure”, http://en.wikipedia.org/wiki/Sound_pressure. [Online]. [Accessed: March 5, 2010]

[4] National Semiconductor. 2003. Tone Decoder. http://www.national.com/ds/LM/LM567.pdf, accessed on March 12, 2010.

[5] ShenzenTopway Technology Co Ltd. 2005. LCD Module User Manual. http://www.mantech.co.za/Datasheets/Products/LMB162ABC.pdf, accessed on March 24, 2010.

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http://www.mantech.co.za/Datasheets/Products/LMB162ABC.pdf

http://www.national.com/ds/LM/LM567.pdf

http://en.wikipedia.org/wiki/Sound_pressure

http://www.kpsec.freeuk.com/powersup.htm#trsr

http://www.mantech.co.za/Datasheets/Products/UT1612MPR.pdf

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AppendixMicrocontroller code:

/*****************************************************

This program was produced by the

CodeWizardAVR V1.25.3 Evaluation

Automatic Program Generator

© Copyright 1998-2007 Pavel Haiduc, HP InfoTech s.r.l.

http://www.hpinfotech.com

Project :

Version :

Date : 10/25/2010

Author : Freeware, for evaluation and non-commercial use only

Company :

Comments:

Chip type : ATmega16

Program type : Application

Clock frequency : 4.000000 MHz

Memory model : Small

External SRAM size : 0

Data Stack size : 256

*****************************************************/

#include <mega16.h>

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#include <stdio.h>

#include <stdlib.h>

#include <delay.h>

#include <string.h>

#include <math.h>

// Alphanumeric LCD Module functions

#asm

.equ __lcd_port=0x15 ;PORTC

#endasm

#include <lcd.h>

// Standard Input/Output functions

#include <stdio.h>

// SPI functions

#include <spi.h>

// Declare your global variables here

int temp ;

char LCD_txt[16];//Buffer for LCD to display text

char Display_LCD[16];//Buffer to display on the LCDvoid main(void)

{

// Declare your local variables here

// Input/Output Ports initialization

// Port A initialization

// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In

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// State7=T State6=T State5=T State4=T State3=T State2=T State1=T State0=T

PORTA=0x00;

DDRA=0x00;

// Port B initialization

// Func7=Out Func6=In Func5=Out Func4=Out Func3=In Func2=In Func1=In Func0=In

// State7=0 State6=T State5=0 State4=0 State3=T State2=T State1=T State0=T

PORTB=0x00;

DDRB=0xB0;

// Port C initialization



PORTC=0x00;

DDRC=0x00;

// Port D initialization



PORTD=0x00;

DDRD=0x00;

// Timer/Counter 0 initialization

// Clock source: System Clock

// Clock value: Timer 0 Stopped

// Mode: Normal top=FFh

// OC0 output: Disconnected

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TCCR0=0x00;

TCNT0=0x00;

OCR0=0x00;




// Mode: Normal top=FFFFh

// OC1A output: Discon.

// OC1B output: Discon.

// Noise Canceler: Off

// Input Capture on Falling Edge

// Timer 1 Overflow Interrupt: Off

// Input Capture Interrupt: Off

// Compare A Match Interrupt: Off

// Compare B Match Interrupt: Off

TCCR1A=0x00;

TCCR1B=0x00;

TCNT1H=0x00;

TCNT1L=0x00;

ICR1H=0x00;

ICR1L=0x00;

OCR1AH=0x00;

OCR1AL=0x00;

OCR1BH=0x00;

OCR1BL=0x00;

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// Mode: Normal top=FFh

// OC2 output: Disconnected

ASSR=0x00;

TCCR2=0x00;

TCNT2=0x00;

OCR2=0x00;

// External Interrupt(s) initialization

// INT0: Off

// INT1: Off

// INT2: Off

MCUCR=0x00;

MCUCSR=0x00;

// Timer(s)/Counter(s) Interrupt(s) initialization

TIMSK=0x00;

// USART initialization

// Communication Parameters: 8 Data, 1 Stop, No Parity

// USART Receiver: Off

// USART Transmitter: On

// USART Mode: Asynchronous

// USART Baud rate: 9600

UCSRA=0x00;

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Electrical Design 4

Energy Meter

UCSRB=0x08;

UCSRC=0x86;

UBRRH=0x00;

UBRRL=0x19;

// Analog Comparator initialization

// Analog Comparator: Off

// Analog Comparator Input Capture by Timer/Counter 1: Off

ACSR=0x80;

SFIOR=0x00;

// SPI initialization

// SPI Type: Master

// SPI Clock Rate: 1000.000 kHz

// SPI Clock Phase: Cycle Half

// SPI Clock Polarity: Low

// SPI Data Order: MSB First

SPCR=0x50;

SPSR=0x00;

// LCD module initialization

lcd_init(16);

while (1)

{

ftoa(Temp,2,Display_LCD);

36

Electrical Design 4

Energy Meter

sprintf(LCD_txt,"Power = %s",Display_LCD);

lcd_gotoxy(0,0);

lcd_puts(LCD_txt);

delay_ms(1000);

lcd_clear();

};

}

void USART_Init( unsigned int baud )

{

UBRRH = (unsigned char)(baud>>8); // set baud rate

UBRRL = (unsigned char)baud; // enable receive

UCSRC = (1<<URSEL)|(3<<UCSZ0); // set frame format

}

void USART_Transmit( unsigned char data )

{

while ( !( UCSRA & (1<<5)) ); // Wait for empty transmit buffer

UDR = DATA; // Put data into buffer, sends the data

}

void SPI_MasterInit(void)

{

37

Electrical Design 4

Energy Meter

DDR_SPI = (1<<DD_MOSI)|(1<<DD_SCK); //Set MOSI and SCK output, all others input

SPCR = (1<<SPE)|(1<<MSTR)|(1<<SPR0); //Enable SPI, Master, set clock rate fck/16

}

void SPI_MasterTransmit(char cData)

{

/* Start transmission */

SPDR = cData;

/* Wait for transmission complete */

while(!(SPSR & (1<<SPIF)))

;

}

void SPI_SlaveInit(void)

{

/* Set MISO output, all others input */

DDR_SPI = (1<<DD_MISO);

/* Enable SPI */

SPCR = (1<<SPE);

}

char SPI_SlaveReceive(void)

{

/* Wait for reception complete */

while(!(SPSR & (1<<SPIF)))

;

/* Return data register */

return SPDR;

}

38

Electrical Design 4

Energy Meter

39

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