Friday, August 28, 2009

robo project

Intelligent spy robo project has been desighed for the spying purpose .it is radio controlled and can be operated at a radial distance of 50 yards. Many time our army jawan need to venture into the enemy area just to track their activities. Which is often a very risky job, it may cost precious life. Such dangerous job could be done using small spy robo all the developed and advance nations are in the process of making combat robo design, a robo who can fight against enemy. Our robo us just a step towards similar activity.
This robo is radio operated , self powered , and has all the controls like a normal car. A laser gun has been installed on it so that it can fire on enemy remotely when required, this is not possible until a wireless camera is installed. Wireless camera will send real time video and audio signals which could be seen on a remote monitor and action can be taken accordingly. Being in size small, will not be tracked by enemy on his radar. It can silently enter into enemy canopy or tent and send us all the information through its’ tiny camera eyes. It can also be used for suicide attack, if required.It has all the control like normal car, self powered through rechargable battery ,stops instantly when stop applied , moving in both the direction turning left and right speed control through pwm.Laser gun for firing purpose wireless camera is installed, sends contineusly audio and video can be monitored on any tv. remotely controlled by looking at remote tv through radio remote control .forward and reverse bumpers are provided,.robo stops instantly in case of bump.saving battery power.

valentine heart project

This project flashes 18 LEDs at three different rates and you can use these to create an eye-catching Valentine Heart. The circuit is kept simple (and low cost) by using the 4060B IC which is a counter and oscillator (clock) in one package. The circuit requires a 9V supply, such as a PP3 battery. It will not work with lower voltages and a higher voltage will destroy the LEDs.

The preset variable resistor can be used to adjust the oscillator frequency and this determines the flash rate of the LEDs. The IC limits the current to and from its outputs so the LEDs can be safely connected without resistors in series to limit the current. The stripboard part of the circuit is easy to build but the wiring for the LEDs needs care so detailed instructions are provided below.

Parts Required

* resistors: 10k, 470k
* preset: 47k (this could be 100k if necessary)
* capacitor: 0.1µF
* 4060B IC
* 16-pin DIL socket for IC
* LEDs × 18, 5mm diameter, red (or any mix of red, orange, yellow and green)
* on/off switch
* battery clip for 9V PP3
* stripboard 13 rows × 18 holes

block diagram of valentine heart project



Stripboard Layout

Building the Circuit

1. Begin by soldering the components onto the stripboard as shown in the diagram above. Do not insert the 4060B IC at this stage.

Arranging the LEDs:

2. Cut out a suitable shape from stiff card (or similar material), such as the Valentine Heart template. Paint or colour the card at this stage if necessary.
3. Plan the layout of the 18 LEDs (suggested positions are marked on the template).
4. Drill 5mm holes for the LEDs - put the card on a piece of scrap wood to do this without damaging the card or the table.
5. Push LEDs into the holes, they should be a fairly tight fit and glue should not be necessary.
6. Label the LEDs D1 - D18 at random on the back of the card.

Wiring of the LEDs:

Use stranded wire for all the connections to the LEDs and solder all wires near to the LED body so the leads can be trimmed short later on.
The wire colours are suggested to avoid confusion but you can use other colours if you wish, the electricity won't mind! For example you could use red and black as suggested but substitute yellow and white for the blue and green suggested.

modern railway level crossing lights

A magnet under the train operates reed switches positioned on the track. The trigger reed switch starts the sequence by switching on the amber light, a few seconds later the two red lights start to flash. When the train has passed the level crossing it operates the cancel reed switch which switches off the lights until the next train arrives.

There is a PCB pattern for this project, but if you don't have facilities to make PCBs you can build this project on stripboard instead.

Parts Required
Level crossing lights

* resistors: 680 ×3, 1k ×3, 33k, 47k, 82k, 270k
* capacitors: 0.1µF ×3, 10µF radial ×2
* red LED (3mm best) ×2
* amber* (or yellow) LED (3mm best)
* some amber LEDs are too orange to look correct, yellow may be better
* 555 timer IC ×3
* 8-pin DIL socket for IC ×3
* on/off switch
* battery clip
* reed switch ×2
* miniature magnet - each locomotive needs one
* printed circuit board (PCB)

block diagram of model level crossing lights




PCB component layout

The reed switches can be held in place between the rails with a small piece of blu tac.
Each locomotive will need a miniature magnet glued to its underside, test first with blu tac, then use superglue.

light sensitive alaram project

The circuit detects a sudden shadow falling on the light-sensor and sounds the bleeper when this happens. The circuit will not respond to gradual changes in brightness to avoid false alarms. The bleeper sounds for only a short time to prevent the battery running flat. Normal lighting can be used, but the circuit will work best if a beam of light is arranged to fall on the light-sensor. Breaking this beam will then cause the bleeper to sound. The light sensor is an LDR (light-dependant resistor), this has a low resistance in bright light and a high resistance in dim light.

* The light-sensitivity of the circuit can be adjusted by varying the 100k preset.
* The length of bleep can be varied from 0.5 to 10 seconds using the 1M preset.

Using the 7555 low-power timer ensures that the circuit draws very little current (about 0.5mA) except for the short times when the bleeper is sounding (this uses about 7mA). If the circuit is switched on continuously an alkaline PP3 9V battery should last about a month, but for longer life (about 6 months) you can use a pack of 6 AA alkaline batteries.

parts required for light sensitive alarm project


Parts Required

* resistors: 10k, 47k, 1M ×3
* presets: 100k, 1M
* capacitors: 0.01µF, 0.1µF, 10µF 25V radial
* transistor: BC108 (or equivalent)
* 7555 low-power timer IC
* 8-pin DIL socket for IC
* LDR (light-dependant resistor) type ORP12
* bleeper 9-12V
* on/off switch
* battery clip for 9V PP3
* stripboard 12 rows × 25 holes

microcontroller programming keypad decode techniques


In the design of electronics project, it is very common to use a keypad matrix as a means for user to interface
to the product. In order to minimize the number of pins used in the microcontroller, the keys should be arranged in as square a matrix as possible. One example is the use of 4 X 4 matrix arrangement in a 16 keys keypad. This arrangement require only 8 pins. If it is arrange in a 2 X 8 matrix, 10 pins will be needed instead of 8.

The microcontroller programming keypad decoding method is as shown in the figure above. There are 4 inputs pins designated as row 1 to row 4 and 4 output pins designated as column 1 to column 4. The 4 input ports need to have a pulldowns resistor to ensure that they are always at a deterministic state either login "0" or login "1". This is achieved by having an internal pulldown resistor in the MCU itself or by having 4 external resisors connected to each of the input pin and ground.

At the start of the scanning, column 1 will be turned ON(login "1") and column 2, 3, and 4 turn OFF (logic "0"). When this happen, the input ports row 1 to row 4 are scanned for its status. If key 7 is pressed, the pin PA2 at row 3 will return as logic "1" and the rest of the rows will return logic "0". By having a debouncing routine as a means of confirmation that the particular key has been pressed, the MCU will know which key is pressed and thus is able to proceed to determine the next action to take.

Low Power Consumption Consideration

In the design of key interface, it is also important to choose a MCU that is able to go into power down mode after a certain time has elapsed. This will ensure that the batteries that are used to power up the MCU will last longer. It will only wake up when a key is pressed. Power down mode typically takes a fraction of current compared to when it is in active mode.

The PDF article below is an example of Motorola MC68HC705J1A Keypad decoding techniques that can be studied and used for any other MCU. The flow chart
and examples of the assembly code are also given.

using reset ic in microcontrller applications



Reset IC in Microcontroller Application Circuitry

In the design of microcontroller based electronics project, the use of Reset IC is critical for highly critical applications
that need to ensure that the MCU will only operate at its optimum voltage. Without the use of reset circuitry, the MCU may go into a tristate of which it may go into abnormal operation.

One example of the use of the Reset IC is that when the input voltage drops below a fixed threshold, the reset IC will asserts a reset signal for a fixed period of time after Vcc rises above the fixed threshold value. An example of how a reset circuit is connected is as shown below.




Using Reset IC in Microcontroller Application Circuit


Reset IC in Microcontroller Application Circuitry

In the design of microcontroller based electronics
project, the use of Reset IC is critical for highly critical applications
that need to ensure that the MCU will only operate at its optimum voltage. Without the use of reset circuitry, the MCU may go into a tristate of which it may go into abnormal operation.

One example of the use of the Reset IC is that when the input voltage drops below a fixed threshold, the reset IC will asserts a reset signal for a fixed period of time after Vcc rises above the fixed threshold value. An example of how a reset circuit is connected is as shown below.







During power up, once Vcc exceeds the reset threshold, the reset line will be kept low for a period after which the line will be pulled high. This resets the MCU afterwhich it will go into normal operation.

If the Vcc drops below the reset threshold, the reset pin will go low. It will stay low for at least the reset time out period and go back to high again. This operation will ensure that the MCU power supply is monitored and will only go into operation when the Vcc is within the range of its operation. The threshold voltage of the IC is chosen based on the minimum Vcc of the MCU. MCU supply can range from 1.8V to 5.0V and a suitable IC can be chosen to monitor the supply voltage to the MCU. A typical range of RESET IC from ST is as shown below.

electronics dice using pic microcontroller circuit


Introduction To PIC Microcontroller Circuit

This PIC Microcontroller Circuit is a good project for those who have yet to have any practical hands-on of using a microcontroller in their electronic project. Once you are familiar with how a microcontroller works, you will be able to do any project using any brand of microcontroller. The price of microcontroller has dropped significantly as the demand for its use increases day by day. They are used in computers, home appliances, mobile phone, control circuitry...... In other words, the use of microcontroller will become more common in our daily lives.

In this project, we want to generate two random numbers between 1 and 6 everytime the Roll switch is pressed and to display the numbers on the 7 segment LED displays for a few seconds. Then we want to be able to press Roll again and get another pair of numbers.

If the Roll is not pressed for about a minute then we want to reduce the power consumption of the circuit. This is done by using the sleep mode available in the PIC IC to save power and hence a longer battery life. Pressing the switch for about a second should wake the PIC from sleep mode and be ready to roll the 2 dice again. A slide switch is built into the circuit so that the unit can be turned completely off when it is not in use. The PIC Microcontroller Circuit diagram is as shown below.

hardware of pic microcontroller

PIC Microcontroller Circuit Hardware Description

There are two I/O ports in the 16C54 - one 8 bit & the other 4 bit. The 8 bit port, Port B, is connected to the 7 segment display. Three pins of the 4 bit Port A are used. The other pin is tied high. Pin 4 of the PIC is also tied high to give a power-on reset.

A 150 ohm resistor acts as a current limiting resistor for each display. PIC ports have a maximum sourcing current of 40mA. The maximum current for the LED display is 200mA so it is the PIC that R1 and R2 is protecting, not the display.

The PIC uses its internal RC clock oscillator option (with the 10K resistor, R3, and the 330pF capacitor, C2) and runs at about 330kHz. The switch is connected to input RA0. Normally this line is pulled high via R4 to +5V, but when the switch is closed the input is pulled low. The software detects the falling edge as a dice roll.

Software Description

When power is first applied, the PIC does a power-on reset. It goes to Start. The first task is to initialize the various internal options such as the direction of the I/O ports and the status of any outputs (high or low.) The watchdog timer
is switched on and the initial value of some RAM locations are set.

The dice now settles down in the main program loop, Main. It continuously loops about 4000 times a second to see if the switch has been pressed, flash the decimal point, generate the next random number and reset the watchdog timer. Then when a Roll (switch press) is detected, the program jumps through to Main02. The two dice are rolled and displayed sequentially in Output. Note how the second random number is generated by the length of time the roll switch is depressed. Display outputs the random numbers to the 7 segment LED displays by multiplexing to them. At the end of Output the program returns to Main.

Various subroutines - Display, Delay, Roll, Flash, Random and two look-up tables for the display, Look_Up_Seg and Look_Up_Digit are listed in the final part of the program. Note the Rand01 code segment in Random and why it is there.

If there is no keypress for 50 flashes then the PIC goes into sleep mode at the end of the Flash subroutine. The oscillator is turned off and ports A & B are configured as inputs.

Now with the PIC in sleep mode the watchdog timer is not being reset anymore. It was not turned off when the PIC went to sleep. It now times out about every 1.3 seconds to check if the key is being pressed. If no keypress is found then it goes back to sleep. But if it is then the PIC wakesup, resets the ports, starts to flash the decimal point and it is ready to roll again on the next keypress.

electronic time clock


This application note from Microchip Technology
uses an 18 pin PIC16C54 microcontroller as its core in the display and settings of a simple 4 digits electronic clock. The four 7 segment displays are connected in a multiplexing method and each segment is sequentially by controlling the Common Cathode of each 7 segment.

The common cathodes are connected to 4 pins of PORTA of the microcontroller. When the pin in PORTA is LOW, the transistor connected to it will turn ON and that particular 7 segment is turn ON. PortB will activate the segments of that particular 7 segment that has been chosen. By multiplexing the selection of the 7 segment sequentially, an equal brightness of all the 7 segments display will be achieved.

Multiplexing has the advantage in that it helps to reduce the number of ports needed to connect to the 7 segments. It also keep the cost of a device low as fewer parts are needed. The setback is that the display may not be as bright as if it is driven directly without multiplexing.

The 3 switches are also connected to PORTB. They are pulled down to logic "0" by using a 10k ohm resistors. Inputs of the switches are detected as logic "1" by the MCU by connecting a pull up resistor to the VDD. Pressing SW1 changes the seconds setting, SW2 the minutes setting and SW3 the hour setting. The full schematic and source code listing can be obtained from Microchip website.

microcontroller design tips in emc

Introduction To Microcontroller Design Tips

As the electronic components continue to shrink in size with the advancement of semiconductor
and packaging technology, the ability of these smaller MCU to withstand the effect of electromagnetic interference is less compared to its bigger size counterparts. Hence the importance of designing electronic devices that can withstand a certain level of immunity in noisy environment has to be considered at the start of a design.

The cycle of a product development using microcontroller design starts at specifications definition, to circuit design, components selection, printed circuit board design, making prototype, reliability and EMC testing, market testing and finally product launch. The cost of EMC consideration and solutions are lowest at design stage and will escalate exponentially when products have been launched to the market. If a device failed due to electromagnetic interference in the market, it will have to be solved on site by using more expensive solutions for instance standalone filters, shieldings etc or even recall from the market if it is a major defect. Hence it is of extreme importance that the EMC design is taken into consideration at the design stage. The followings are some tips that one may consider when designing any electronics device.

Microcontroller Design Component Selection

As far as possible, the components used should be leadless type instead of leaded type as the leaded type have more parasitic and capacitive effect at high frequencies. Surface mount resistors, capacitors, inductors, and other SMT components are preferred. MCU selection is done based on the assurance and specifications from the manufacturer that the EMC aspects are taken into consideration in the design of the device. For instance, build in clamping diodes at the inputs of the ports to reduce the effect of electrostatic discharge on the ports.

microcontroller design printed circuit board

* Placed each component as close as possible to each other as this will reduce the looping and tracks and hence the parasitic and capacitive inductance will be reduced. Each loop or track will radiate and absorb energy once it is exposed to a variation of current, voltage or electromagnetic flux.

* Place the crystal or ceramic oscillator as close possible to the microcontroller. The tracks used to connect the resonator to the clocks should be as short and close as possible.

* As far as possible, do not use any socket between the MCU and the PCB. Use of socket introduces parasitic inductance and capacitance to the circuit.

* Use a 0.1uF ceramic capacitor across the power supply(VCC-Ground) of each integrated circuit as a high frequency decoupling device. The capacitor should be placed as close as possible to the integrated circuit.

* IO ports of MCU that are not used should be tied to Ground or connected to VCC through a high impedance resistor (100-200 kohm). This is to reduce the effect of voltage spike to the unused port that may cause wrong logic to be read by the MCU.

* Separate the grounding of digital and analog tracks.

* It is good to put a large ground underneath the MCU to create a stable tank to divert the noise to the ground.

* In critical application, use a reset IC that will reset the circuit once the power supply drops below a certain level.

* The power supply to the system should be stable by using large filtering capacitors and bypass ceramic capacitors and ensuring that the ripple is minimal(less than 100mV).

Microcontroller Design Software Consideration

* As far as possible, try to reconfigure the ports configuration, timer configuration and other registers regularly in the software loop. In a noisy environment, the setting of the registers may be flipped and changed from input to output and vice versa.

* Place a certain value in the RAM of the MCU and check for its integrity regularly. If the values changed, it means that the noise have altered the values and the integrity of the rest of the RAM is questionable. You may make a decision to reset the RAM to a predetermine value.

* Use a MCU with a hardware reset watchdog feature. A timer routine is placed in a certain part of the software where it will be refresh at a certain time. If this is not updated, it means that the program has runaway and a hardware reset should be triggered.

* Unused memory should be filled with "1111...." or "0000...."

* Unused program memory should be filled NOP(No operation) instruction codes. This is to ensure that if the program counter of the MCU is corrupted and jumped to these areas of the program memory, it will not end in endless loop.

microcontroller based project led driver

Microcontroller Based Project LED Driver

This project uses Microchip Flash based microcontroller PIC16F785 that uses buck boost converter
circuit to drive a superbright 5.5W LED module that consumes up to 700mA of current. The LED used in this project is BL-4000 series White 5500K LED Light from Lamina. The buck boost converter circuit is derived from switching power supply
applications which is becoming more common as the overall solution is smaller in size and more efficient compared to linear power supply solutions.

The 20 Pin Flash PIC16F785 is a good device to use as it offers many features some of which are listed below.

* 2048 Words Program Memory, 128 bytes Static RAM, 256 bytes EEPROM.
* Wide Operating Voltage from 2.0V to 5.5V DC.
* 18 I/O.
* 12 channels of 10 bit Analog to Digital Converter.
* 2 operation amplifiers.
* 2 high speed analog comparators and Bandgap voltage reference.
* Capture/Compare/PWM module.
* 2 phase PWM with asynchronous feedback.
* 1 16-bit timer.
* 2 8-bit timers.

The BL-4000 series LED module has a forward voltage drop of approximately 8V for a current limit of 700mA. The on chip operational amplifier is used to amplify the voltage across the resistor that is used to sense the current of the circuit.

This application note from Microchip provides the schematics, source code and some theoretical aspects of buck boost converter for those who are new to switching mode power supplies and its principles of operation. This project is a good hands-on for electronics designer or hobbyist who are keen to go into the detailed operation of a switching mode power supplies and the latest technology of superbright power LEDs.

block diagram of mc controlled drive

final year electronic projects

It is usually the norm of students in the field of electrical, electronics, telecommunication, computer or communication of most universities and colleges to complete a final year project. Each must synthesize the theory and experimental work they learned during the first two to three years in order to complete the project. Under the supervision of their faculty supervisor, they must research, design, execute, document, and then present their work to the supervising committee.

A list of suitable topics will be offered by the university, from which preferred topics may be selected. Students sometimes will also have the opportunity to propose topics of their own devising, subject to approval for suitability.

Some of the projects which students may want to consider and get some ideas from are listed below. It usually involves the use of a microcontroller or a microprocessor in these projects. A lot of applications and ideas can be modified and build once they are familiar with circuit theory and operation.

Among the projects that one can consider is the utility metering projects which will become a norm in the near future. Hands-on of microcontroller projects will enable one to familiarise himself with the assembly language, C language and other tools that are used in the project.

Some of the final year electronic projects that one can get some ideas from are listed below.

Final Year Electronic Projects - Metering Project
Electronic meters compared to traditional mechanical solutions in use offer several additional advantages to the utility market. The metering utilities that can be replaced are gas, water and electricity meters.


Biometrics Digital Signal Processing Project
Biometrics is the technology used to analyze biological data. Its most recent application is in the area of security where the biological data of a person is used for personal identification and authentication before the person is allowed to proceed to enter a building or do any business transactions.


Bluetooth Technology
Bluetooth technology is a radio frequency short range communications technology that was created with the intention of replacing wired cables that are used to connect various portable and fixed devices. Get some reference design for your final year electronic projects here.


USB2.0 Card Reader Design Project
This project provides a reference USB2.0 Card Reader design with schematics and source codes
for Compactflash, Memory Stick, Memory Stick Duo, Magic Gate, Secure Digital, MultimediaCard and SmartMedia.


X10 Home Automation Project
This project discusses the implementation of X-10 on a PIC microcontroller to create a home controller that can both send and receive X-10 signals.


Sensorless Brushless DC Motor Control Project
This project provides the application notes on the control of 3 phase sensorless brushless DC Motor.


Lighting Networking System Project
This project provides the application notes on the networking control of lighting devices using Digitally Addressable Lighting Interface Standard.


Zigbee Wireless Project
This project provides the application notes on the free frequency band wireless networking using Zigbee Standard.

digital signal processing

Introduction To Digital Signal Processing

DSP or Digital Signal Processing is the technology
of manipulating analog information that has been obtained from sources such as sound or photography data that have been converted into digital format. It uses complex mathematical formulas to the raw data to form another type of modified output. It uses the compression technique to transmits and display information effectively.

Products such as video conferencing uses complex hardware and software DSP processing. Many of these products have dedicated DSP chips where they are placed into the sound card that provide extra audio processing power to reduce the loading of processing in the CPU. In the total system solution, the DSP technology collects the raw data, process it, compress it, trasmit it and display it once again in the various digital display devices.

Digital Signal Processing In Biometrics

Biometrics is the technology used to analyze biological data. Its most recent application is in the area of security where the biological data of a person is used for personal identification and authentication before the person is allowed to proceed to enter a building or do any business transactions. Fingerprint, iris scan and facial features are among some of the human biometrics used.

The development
of single chip DSP microcontroller that processes the electrical signals generated by the transducers such as digital camera CCD devices and fingerprint sensors have helped to speed up the processing power and hence make authentication easy and efficient.

One of the industry leader in DSP technology is Texas Instruments which have developed dedicated microcontroller for DSP application. The technology that have been developed in Biometrics are discussed in great details and is a great source of design references for students or even electronics designers who are keen to develop a biometrics based DSP system.

bluetooth technology

Introduction To Bluetooth Technology

Bluetooth technology is a radio frequency short range communications technology that was created with the intention of replacing wired cables that are used to connect various portable and fixed devices. The use of this technology will do away with the physical cables that connect devices. The key features are its low cost, low power and robustness in maintaining high level of security.

Bluetooth was made possible by the Bluetooth Special Interest Group(SIG) which was founded by Ericsson, IBM, Intel, Nokia and Toshiba in the year 1998. The objective was to develop an open specifications for short range wireless connectivity. More than 1900 companies have since joined the SIG and the numbers are increasing day by day.

Specifications

The specifications provide developers the link layer and application layer definitions which are used to support both voice and data applications. The spectrum of frequency used is in the unlicensed ISM(Industrial, Scientific and Medical) band at 2.4 Ghz to 2.485 GHz using spread spectrum and frequency hopping. As this is a free band, there is no cost for the use of Bluetooth compared to cellular phones where one must subscribe to use the network of GSM or CDMA.

IEEE 802.15.1 standard is used in the development of Bluetooth enabled products. The versions used are Ver 1.2 with data rate of 1 Mbps and ver 2.0 with data rate of up to 3 Mbps. The range of operation depends on the device classes. They are:

Class 3 – 1 meter range with maximum permitted power set at 1mW.
Class 2 – 10 meters range with maximum permitted power set at 2.5mW.
Class 1 – 100 meters range with maximum permitted power set at 5mW.

Bluetooth Applications

The technology allows the data and voice transmissions to be handled simultaneously. Hence, Bluetooth applications have been used in communications solutions such as hands free headset, mobile phones, laptop, PDA, printers
, mouse, keyboard, MP3 players and fax machines amongst others. As this technology is made available in the global scale, one will be able to find many products that exhibit such capability.

In Voice over IP (VOIP) application, Bluetooth headsets are being used as wireless extensions to the PC audio system. As VOIP becomes more popular compared to wired phone, Bluetooth may be used in Cordless handsets, with a base station
connected to the Internet link.

One good link for free downloading of Bluetooth technology design is from IVT Corporation. It is a world leader in providing Bluetooth Technology and Fixed-Mobile Convergence(FMC) Solutions.

usb circuit design

Introduction To USB Circuit Design

USB is an acronym for Universal Serial Bus and is the technology that enables the connections between computer and external devices over a cable using bi serial transmission.

It has 4 connections to it i.e. Vcc, Gnd, Data + and Data -. The devices can be connected to the computer without turning OFF the personal computer. It is able to support data speed from 12Mbps (USB1.0, USB1.1) up to 480Mbps(USB2.0). This type of connection is fast replacing RS232 and parallel port in many PCs. As it is now, many laptops no longer has any provision for RS232 connections.

Peripheral devices that are designed to USB complaint are increasing every day. Some of them that are commonly seen by consumers are keyboard, mouse, modem, joystick, digital camera, microphone, scanners, printers, storage devices, web camera and telephones.

USB was implemented in all personal computers since 1997. Windows 98 was the first Windows that has built in drivers to support its implementation. One big advantage of the USB is its capability to be connected up to 127 devices to a computer.

USB can have 2 types of connections. They are type A (rectangular) and type B (square). Type A is usually connected to the PC and type B to peripheral devices. Expansion of the USB is done by using a USB port hub.

In a typical design, if a device is using less than 500mA/5V supply, it is usually better to tap the power from the computer. The type of data transfer between the computer and the devices are interrupt (e.g. mouse), bulk (e.g. printer) or isochronous (e.g. speakers).

USB Circuit Design (USB2.0)

USB2.0 version standard was released on April 2000 and is an upgrade version of USB1.1. It has better bandwidth and data transmission speed up to 480 Mbps compared to USB1.1 which has only 12 Mbps. This makes it an ideal applications for multimedia and storage devices. It is backward compatible to USB1.0/USB1.1 as it supports 1.5Mbps, 12Mbps and 480Mbps.

The following USB2.0 reference project from Freescale Semiconductor describes in detailed the design of a USB2.0 Card Reader. It support cards such as Compactflash, Memory Stick, Memory Stick Duo, Magic Gate, Secure Digital, MultimediaCard and SmartMedia. The schematic and source code of the reference projects are provided. This USB Circuit Design Project is a good reference for students who need to do an electronics project in their final year of studies.

x10 home automation project

Introduction To X10 Home Automation

X-10 is a communication protocol designed for sending signals over 120 VAC wiring. X-10 uses 120 kHz bursts timed with the power line zero-crossings to represent digital information. X10 components send signals through your home electrical wiring. There are 16 house codes and 16 unit numbers per house code available on your network for a total of 256 addresses. You can control multiple devices by setting them the same house code.

X10 plug in modules are now commonly used in the area of security, lighting, control of TV, motion detectors and other applications. It should be noted if there is no filter at the house breaker box, signals can pass from one house to another and cause odd behavior. If you have problems with a device on a given house and unit code, experiment with other codes and see if the problem goes away.

X-10 transmissions are synchronized with the zero-crossings on the AC power line. By monitoring for the zero-crossings, X-10 devices know when to transmit or receive X-10 information. A binary ‘1’ is represented by a 1 ms long burst of 120 kHz, near the zero-crossing point of the AC. A binary zero is represented by the lack of the 120 kHz burst.


X10 Home Automation Project

This application note discusses the implementation of X-10 on a PICmicro MCU to create a home controller that can both send and receive X-10 signals. The reader may implement the home controller as is, or adapt the circuits and firmware to other applications. A library of X-10 functions is provided to facilitate development of other X-10 applications using PICmicro microcontrollers.

It allows the user to program on and off times for up to sixteen devices, using a 2 x 16 liquid crystal display and five push buttons. A built-in light sensor can be used to turn on lights at dusk, and turn them off at The home controller is designed to facilitate experimentation with home automation using the PIC16F877A.

It will be a good project for final year students to embark on and hence gain a considerable experience in X10 wireless technology.

sensorless bldc motor power inverter circuit design project

Introduction To Power Inverter Circuit Design

Power electronics motor control have evolved from simple ON/OFF control to more complex electronic control circuitry in recent years. In the area of consumer electronics, the products that have been impacted by inverter based technology are air conditioners and washing machines and refrigerator.

The inverter technology development has been moving at a fast pace in the quest for more efficient and environmental friendly products. Energy savings have been the key drivers as our the oil and gas resources of our earth is fast depleting. The inverter development started from AC inverter control which evolved to DC inverter control and recently sensorless brushless DC motor control. The sensorless BLDC motor inverter control has more complex circuitry but is far more efficient and long lasting compared to AC inverter control.

Brushless DC Vs Sensorless Brushless DC Control

In BLDC control, a few Hall sensors are placed on the stator of the motor to detect the position of the rotor during the operation of the motor. The sensors are normally build into the printed circuit board and mounted onto the enclosure cap of the non driving end of the motor. The setback of this method is that the sensors and PCB need to be placed in a location where the temperature of the motor will not build up and thus affect the lifetime and operation of the PCB.

In Sensorless BLDC control, there is no need to have any Hall sensors to sense the position of the rotor. The sensing of the rotor position is by the analysis of the back electromotive force that is generated at the stator of the motor windings. By using this method, the reliability of the control system is enhanced. The setback of this method is that the algorithm and control circuit to detect the back EMF is complex, hence requiring more powerful microcontroller and software knowledge.

Power Inverter Circuit Design Application

A good sensorless BLDC motor Power Inverter Circuit Design Application Notes and its source codes can be downloaded from Microchip website. The control circuitry functions include the sensing of Back EMF, the driving of DC Motor using IGBTs, detection of overcurrent and RS 232 communications interface.

home lighting system project

Introduction To Home Lighting System

In recent year, the control of Home Lighting System
has developed from standalone type to more complicated networking controls. Many building management system
and even the security system have incorporate the control of lighting into their system as a total solution to their customers. However, there are still no single universal protocol for the building or lighting control system.

The lighting industry has developed a new standard for communication with electronic ballast. Electronic ballast is a common lighting device that is used in practically every building, factory or residential house. This standard called IEC 929 is an interface standard for communication between a controller and the electronic ballast. The standard for the control is called DALI, an acronym for Digital Addressable Lighting Interface. DALI is meant for home or industry use which has 2 wire communication connection between the master-slave and slave-slave. It is developed to reduce the cost of implementation.

Among the features that can be applied are dimming features and control for different grouping/section of the building.

The electronic ballasts can have up to 16 groups and each group can have up to 16 different lighting parameters for the lighting scenes. Each controller can controlled up to 64 electronic ballasts.

There are many ways to implement the DALI depending on the cost and requirements of a home or building. Most of the time, a microcontroller is used at both the slave and the master controller units as this is one of the most cost effective ways to implement the system.

zigbee emerging wireless system

Introduction To Zigbee

In the wireless world, the name Bluetooth
and WIFI have become a household name in recent years. They quickly find applications amongst others in mobile computing and mobile phones.

Zigbee is the result of the demand from industry and consumer for wireless applications that demand for lower data rate, longer battery life, simple design, shorter range and low cost solutions.

Introduction To IEEE 802.15.4

IEEE 802.15.4 is a simple standard that specifies the Media Access Controller (MAC) and Physical (PHY) networking layers for packet data protocol. Its license free frequency bands are:

2.4 GHz (16 channels with baud rate of 250 kps)
902 MHz - 928 MHz (10 channels with baud rate of 40 kps)
868 MHz - 870 MHz (1 channel with baud rate of 20 kps)

North America, Europe, Australia and New Zealand use the sub 1 GHz bands whereas the rest of the world uses 2.4 GHz bands.

It uses Carrier Sense Multiple Access with Collison Avoidance for Channel Access.

The security method used is AES-128.

Has message acknowledgement and a host of other features.

Zigbee Applications

Zigbee technology is based on IEEE 802.15.4 industry standard. It incorporates the standard, adding the logical network, security and software to it. It supports up to 3 network topologies namely STAR, MESH and CLUSTER tree. Developers need only have to focus on application while the MCU/Microprocessor/RF Transceiver makers and Zigbee Alliance take care of the RF Transmitter, RF Receiver, RF Channel and its protocol.

There are 3 types of traffics that can be used.

a) Periodic data

An example of this traffic is a wireless sensor to read the water meter. The sensor is programmed to wake up at certain interval to transmit the information needed and goes back to sleep after this is done.

b) Intermittent data

An example of this traffic is a wireless light switch to ON or OFF a light manually. It is triggered only by external input and hence wakes up to transmit the message to the network. When done, it is disconnected to the network and hence save energy.

c) Repetitive data

An example of this traffic is the security system monitoring. The devices are time multiplex to return its status to the network. This type uses more energy.

There are numerous applications that can be implemented using Zigbee. Amongst others are in the industry and home applications.

In the industry, the applications include utility and metering where gas/water/electricity meter readings are automated and send back to utility headquarter for further action. This saves the time it takes for their personnel to come to the premises to take its reading. In the area of warehousing/inventory management , the wireless technology will enable accurate and hassle free management of goods. Security and access control, building management system and lighting control are among the applications that can be implemented with ease.

In the home, a total home automation system to control lightings, blinds, air conditioning, security system, remote control and appliances can be implemented.

automotive electronics

In automotive electronics networking, the commonly networking standard used is called CAN or controller area network which uses a baud rate of up to 1Mbps. This speed is needed in the control of engine and other critical components of the automobile that requires fast transfer of information. However, there are some areas of control which does not require that kind of speed and hence a slower speed standard can be utilised to save control cost. Some of these areas are the mirrors control, Window lift, seat control and door lock amongst others.

Due to this requirements, a consortium was formed in 1998 consisting of 5 automotive manufacturers (Volvo, BMW, Audi, VW and Daimler-Chrysler), 1 tool supplier (VCT) and 1 semiconductor supplier (Motorola) to look into this. As a result, the LIN (Local Interconnect Network) specifications was finalised on 2 February 2000. The first version of LIN was 1.1 and currently version 2.0 is in use. The most recent development
in LIN is the use of it over the vehicle's battery line using a DC-LIN transceiver. Some of the main features of LIN are listed below.

* One master and up to 16 slaves. No collision detection feature is needed as master initiated all messages communication with slaves. The master is usually implemented with a more powerful microcontroller compared to the slaves as it has to handle more tasks.

* Baudrate of up to 20kbps. Slower speed is chosen to reduce the effect of electromagnetic interference.

* Single wire implementation based on enhanced ISO 9141.

* Simple SCI or UART hardware interface which is available in most microcontroller chips making its implementation cost effective.

* Self synchronization in the slave nodes without the need to have crystal or ceramic resonator. Internal RC oscillator for the microcontroller is good enough and hence making its implementation lower cost.