shyamsunder: 2011

It is an embedded controller circuit to switch on and off electrical appliances. This system will use normal TV remote control to send the control signal.

The TV remote control sends different control signals as per the key pressed. This control can be used for decoding and select some of the out pin of the microcontroller. It is convenient for the user to operate the electrical appliances.

The TV remote control sends control signals in the form of rays to the receiving unit. The receiving unit receives the signals. The signal will be converted into digital signal with the help of an receiver. The received signals are decoded by the micro controller and changes its output with respect to the code received. Controller also controls speed of fan like ac induction motor, where unable to access motor. So it can be used in industrial applications.

1. Easy operation

2. Convenient Affordable

Required Skill Sets :

1. Understanding

2. Assembly Language programming

3. Understanding interfacing techniques

4. Knowledge on sensors

5. Design and Fabrication of PCB

Project Phase :

1. Schematic design and drawing of PCB

2. Design the Interfacing Circuits for micro controller

3. Preparation of PCB

4. Assembling and Testing of Interfacing Circuits

5. Code for the application

6. Debugging and testing

7. Project Report

INDEX

CHAPTER I

INTRODUCTION

1.1 Overview

1.2 Block Diagram

1.3 Remote Receiving Unit

CHAPTER II

MICRO CONTROLLER

2.1 Introduction

2.2 Comparison of Microprocessor & Microcontroller

2.3 Flash Rom

2.4 Ram

2.5 Advantage of Microcontroller

CHAPTER III

ABOUT 8051 FAMILIES :

3.1 Features

3.2 Pin Configuration

3.3 Block Diagram

3.4 Pin Description

3.5 Special Function Registers

3.6 Memory Organization

CHAPTER IV

CODING

4.1 Transmitter

4.2 Receiver

4.3 TRIAC

CHAPTER V

5.1 Power Supply Circuit Description

5.2 Power Supply Circuit Diagram

5.3 Hardware Description

5.4 Circuit Diagram

5.5 Flow Chart

5.6 Assembly Code

INTRODUCTION

1.1 Overview :

This project is using an embedded controller circuit to decode their signals and switch on and off electrical appliances connected with this system.

In every home we use many electrical appliances switched on and off manually. It is convenient if we have remote on/off facility. But lamp and fans are not coming with remote control facility. This project aimed to provide remote control facility to the electrical appliances and gadgets.

This project on the embedded micro controller also demonstrates its effective and easy controlling nature. Moreover, the control algorithm is easily understandable so anyone can follow the same.

1.2 Block Diagram :

1.3 Remote Receiving Unit :

The remote receiving unit receives the signals coming from the TV remote control unit. These signals are converted into electrical signals by the help of IR receiver. The TV remote control sends the control signals with RC5 protocol. The microcontroller receives the signals and it decodes the control signals. As per the control signal is changes the states of its port terminals.

The micro controller port terminals are used to switch on/off the opto coupler. The op to coupler includes a light activated DIAC. This DIAC will switch on/off the TRIAC gate terminal. Hence the TRIAC will works like an on/off switch for the AC circuit. The electrical apparatus attached with the TRIAC will be made on/off.

To achieve these functions following devices were used.

i. Receiver :

The IR sensor will receive the Infra Red signals send by the TV remote control. The control signals are modulated on 40 khz signal in order to avoid external light. The sensor converts the IR signal into electrical signals with the help of photo diode and amplifies it. It also includes the filter circuit to demodulate the 40khz carrier signal. The sensor inverts the signals.

ii. TRIAC :

The TRIAC is a bilateral switch. Which can be used for controlling ac devices. When the gate terminal is injected with dc current it works like a closed switch otherwise it behaves like an open switch.

Also the TRIAC can be made on if the gate is made positive while its main terminal 1 is positive. During this situation it allows the positive half cycle of the ac. Similarly the gate should be negative when the main terminal 1 is negative to allow the negative half cycle. In other conditions it behaves like a open circuit.

iii. Micro Controller :

The 89c2051 micro controller is used in this project. It is in the family of Intel 8051. It is a CISC type processor and having 256 instructions. It has a 16-bit timer and UART. The controller receives the signals, which are in RC5 protocol. It decodes the control signals and changes the port status. Also it display speed of fan.

iv. Remote Transmitter

The remote transmitter used in this project is a TV remote control used for Phillips TVs. It sends the control signals, which are in RC5 protocol modulated on a 40khz carrier signal.

MICRO CONTROLLER

2.1 Introduction :

Microcontroller these days are silent workers in many apparatus, ranging from the washing machine to the video recorder. Nearly all of these controllers are mask programmed and therefore are of very little use for applications that require the programs to be changed during the course of execution.

Even if the programs could be altered, the information necessary to do so an instruction set, an assembler language and description for the basic hardware is either very difficult to obtain or are in adequate when it came to the issue of accessibility.

A marked exception to the above category is the atmel 89C2051 microcontroller belonging to the Atmel family. This microcontroller has features that seem to make it more accessible than any other single chip microcontroller with a reasonable price tag.

The 89C2051, an 8 bit single chip microcontroller has got a powerful CPU optimized for control applications, 64K program memory address space, 64K data memory address space, 128 bytes of on chip RAM (read /write memory), for 8 bit bi-directional parallel ports one full duplex serial ports two 16 bit timers / counters and an extensive interrupt structure.

The 89C2051 is a second –generation 8-bit single chip microcontroller. The 89C2051 provides a significantly more powerful architecture, a more powerful instruction set and a full serial port. The 89C2051 is a complete micro controller. There are 20 pins needed by the two 8 bit bi-directional ports. Pins provide power, allow you to connect a crystal clock and provide a few timing and control signals. The architecture includes the ALU, the accumulator, the stack pointer; a block of registers and a general purpose register-the B register. All these devices are connected to the 89C2051 internal 8-bit data bus.

Each I/O port is also connected to the 8-bit internal data bus through a series of registers. These registers hold data during I/O transfers and conatrol the I/O ports. The architectural block diagram also shows the 89C2051 ROM and RAM.

2.2 Comparison of Microprocessor and Microcontroller

The difference between Microprocessor and Micro controller is Microprocessor can only process with the data, Micro controller can control external device. That is if you want switch “ON” or “OFF” a device, you need peripheral Ics to do this work with Micro controller you can directly control the device.

Like Microprocessor, Micro controller is available with different features. It is available with inbuilt memory, I/O lines, timer and ADC. The micro controller, which are going to use, is 89C2051 it is manufactured by ATMEL, MC, and

USA

. This is advanced version of 8031. This Micro controller have inbuilt 4K bytes of flash ROM, 256 bytes of RAM, 32 I/O lines (4 bit ports) and 6 vectored interrupts.

2.3 Flash ROM :

Flash ROM can be well explained with a block diagram as shown in the following figure. 4-Kilo byte ROM is available in the Micro controller. It can be erased and reprogrammed. If the available memory is not enough for your program, you can interface the external ROM with this IC, it has 16 address lines, so maximum of (2 16) i.e. 64 bytes of ROM can be interfaced with this Micro controller. Both internal and external ROM cannot be used simultaneously.

OFFF

Internal

ROM

External

ROM

OFFF

0000

For external accessing of ROM, A pin is provided in Micro controller itself is i.e. pin no. 31 EA should be high to use internal ROM, low to use external ROM.

2.4 RAM

Internal 265 bytes of RAM are available for user. These 256 bytes of RAM can be used along with the external RAM. Externally you can connect 64-kilo bytes of RAM with micro controller. In internal RAM first 128 bytes of RAM is available for user and the remaining 128 bytes are used as special function registers (SFR). These SFR’s are used as control registers for timer, serial port etc.

2.5 Advantages of Microcontrollers

1. If a system is developed with a microprocessor, the designer has to go for external memory such as RAM, ROM or EPROM and peripherals and hence the size of the PCB will be large enough to hold all the required peripherals.

2. But the microcontroller has got all these peripheral facilities on a single chip so development of a similar system with a microcontroller reduces PCB size and cost of the design.

3. One of the major difference between a microcontroller and a microprocessor is that a controller often deals with bits, not bytes as in the real world application, for example switch contacts can only be open or close, indicators should be lit or dark and motors can be either turned on or off and so forth.

4. The Microcontroller has two 16 bit timers / counters built within it, which makes it more suitable to this application since we need to produce some accurate timer delays. It is even more advantageous that the timers also act as interrupt.

ABOUT AT89C2051

The AT89C2051 is a low –power, high –performance CMOS 8-bit micro computer with 2K bytes of Flash programmable and erasable read only memory (PEROM). The device is manufactured using Atmel’s high –density nonvolatile memory technology and is compatible with the industry-standard MCS-51 instruction set and pin out. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C2051 is a powerful microcomputer, which provides a highly flexible and cost-effective solution to many embedded control applications.

The Atmel AT89C2051 is a powerful microcontroller that combines a versatile 8-bit CPU with in –system programmable Flash on a monolithic chip, providing a highly flexible and cost-effective solutions to many embedded control applications.

3.1 Features

· Compatible with MCS-51^TMProducts

· 2K Bytes of In-System Reprogrammable Flash Memory

· Endurance: 1,000 Write/Erase Cycles

· Fully Static Operation : 0Hz to 24 MHz

· Three –level Program Memory Lock

· 128 x 8-bit Internal RAM

· 16 Programable I/O Lines

· Two 16-bit Timer/Counters

· Six Interrupt Sources

· Programmable Serial Channel

· Low-power Idle and Power –down Mode

In addition, the AT89C2051 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM; timer/counters, serial port, and interrupt system to continue functioning. The Power-down mode saves the RAM contents but freezes the oscillator, disabling all other chip functions until the next interrupt or hardware reset.

3.2 PIN Configuration

3.4 PIN Description

· VCC Supply voltage

· GND Ground

Port 1

Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 1 output buffers can sink/source four TTL inputs. When is are written to Port 1 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups.

In addition, P1.0 and P1.1 can be configured to be the timer/counter 2 external count input (P1.0/T2) and the timer/counter 2 trigger input (P1.1/T2EX), respectively. Port 1 also receives the low –order address bytes during Flash Programming and verification.

Port 3

Port 3 is an 8-bit bidrectional I/O port with internal pull-ups. The Port 3 output buffers can sink/source four TTL inputs. When 1s are written to Port3 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the pull-ups. Port 3 also serves the functions of various special features of the AT89C2051, as shown in the following table.

RST – Rest input. A high on this pin for two machine cycles while the oscillator is running rests device. This pin drives high for 98 oscillator periods after the Watchdog times out. The DISRTO bit in SFR AUXR (address8EH) can be used to disable this feature. In the default state of bit DISTO, the RESET HIGH out features is enable.

XTAL1 - Input to the inverting oscillator amplifier and input to the internal clock operating circuit.

XTAL2- Output from the inverting oscillator amplifier.

3.5 Special Function Registers

A map of the on-chip memory area called the Special Function Register (SFR).

Space is shown in Table 1.

Interrupt Registers : The individual interrupt enable bits are in the IE register. Two priorities can be set for each of the five-interrupt sources in the IP register.

AUXR: Auxiliary Registers

3.6 Memory Organization : MCS – 51devices have a separate address space for Program and Data Memory. Up to 2K bytes each of Program and Data Memory can be addressed.

Input / Out Ports

Here the microcontroller used is AT89C2051.

One major feature of a microcontroller is the versatility built into the input/ output (I/O) circuits that connect the AT89C2051 to the outside world. To be commercially viable, the AT9C2051 had to incorporate as many functions as were technically and economically feasible. The main constraint that limits numerous is the number of pins available to the AT89C2051 circuit designers.

There are two I/O ports available in ATMEL 89C2051. The micro controller consists of 20 pins. They are port 1 and port 3. All these ports are eight bits ports. All these ports can be controlled as eight – bit port or it can be controlled individually. One of the main features of this micro controller is it can control the port individually. For example to control a LED we need to use one I/O line in microcontroller with 8255 we have to use an eight bit port. In 89C2051, prt1, is available for users, port 3 is combined with interrupts. This can be used as interrupts (or) I/O ports.

Each I/O port is also connected to the 8-bit internal data bus through a series of registers. These registers hold data during I/O transfers and control the I/O ports.

All these port lines are available with internal pull-ups except port 0. If we want to use port 0 as I/O port we have to pull-up resistors.

This microcontroller is working in a speed of maximum of 24 MHZ. It is available with in built oscillator, just we have to connect the crystal to its terminal.

CODING

4.1 Transmitter

The transmitter used in this project is a remote control unit used for Philips TV. RC5 protocol system is used in this remote control.

RC5 control protocol is one of the most popular and is widely used to control numerous home appliances, entertainment systems and some industrial applications including utility consumption remote meter reading, contract-less apparatus control, telemetry data transmission, and car security systems. Philips originally invented this protocol and virtually all Philips’ remotes use this protocol.

RC5 Protocol

A TV infrared remote control must receive user commands through button-presses and output the appropriate IR signal through the air to an IR receiver. To allow the receiver to distinguish between the remote’s IR signal and all the other sources of infrared light, IR remote controls modulate their signals, usually between 30-60 kHz. In this application report, 40 kHz is used.

A mark is defined as the presence of a 40 kHz modulated IR signal and a space is the lack of an IR signal. The specific IR protocol defines the how the series of marks and spaces translate to a user command the RC5 protocol is a type of Manchester encoded data spacket. Manchester data is unique in that a data is signified by a transition in the middle of the bit. A one is transmitted as a space to-mark transition and a zero as a mark-to-space transition. The RC5 IR packet consists of 14 bits. two start bits (S1, S0), one control bit (C), five address bits (A4 to A0) and a six bit command code (C5 to C0). The entire 14-bit packet is received MSB first, starting with two start bits.

Following is a description of the RC5. When the user pushes a button on the hand-held remote, the device is activated and sends modulated infrared light to transmit the command. The remote separates command data into packets. Eachd data packet consists of a 14-bit data word, which is repeated if the user continues to push the remote button. The data packet structure is the start bits are always logic ‘1’ and intended to calibrate the optical receiver automatic gain control loop. Next, is the control bit? This bit is inverted each time the user releases the remote button and is intended to differentiate situations when the user continues to hold the same button the next 5 bits are the address bits and selected the destination device.

A number of devices can use RC5 at the same time. To exclude possible interference, each must use a different address. The 6 command bits describe the actual command. As a result, a RC5 transmitted can send the 2048 unique commands. The transmitter shift the data word, applies Manchester encoding and passes the create done-bit sequence to a control carrier frequency signal amplitude modulator. The amplitude modulated carrier signal is sent to the optical transmitter, which radiates the infrared light. In RC5 systems the carrier frequency has been set to 36 kHz. Figure 1 displays the RC5 protocol. The receiver performs the reverse function. The photo detector converts optical transmission into electric signals, filters it and executes amplitude demodulation. The receiver output bit stream can be used to decode the RC5 data word. This operation is done by the microprocessor typically; the receiver output is inverted (log. 1 corresponds to illumination absence).

4.2 Receiver :

The TSOP17 is a miniaturized receiver for remote control systems. PIN diode and preamplifier are assembled on lead frame, the epoxy package is designed as IR filter. The demodulated output signal can directly be decoded bya microprocessor. TS0P17. Is the standard remote control receiver series, supporting all major transmission codes.

A logical 1 indicates the presence of 40 kHz modulated IR, and a 0 indicates its Absence. The 40-kHz modulation is used to filter out natural forms of IR present from sources such as sunlight or office florescent lights. While 40 kHz is the most common modulation frequency, some systems use other frequencies in the 32-kHz to 64-kHz range. In order to decode RC5 or SIRC signals, the 40-kHz modulation must first be removed to expose the actual data bits in the serial packet. A simple three-pin TSOP sensor is used in this report to amplify, filter, and demodulate the IR signal, providing a clean logic – level output with only the serial data present. With no 40-kHz IR modulation present, the sensor output is high; when 40-kHz IR is present, the output is low. Thus, the sensor also has the effect of inverting the transmitted data in addition to removing the modulation. The IR-sensor output is connected directly to micro controller.

The micro controller port pin will change as per the data received by the IR receiver. This data are collected serially be generating a clock pulse for duration of 1.8 msec. The serial data is assembled into parallel by shifting method. Then the control codes were decoded to identify the button pressed. Accordingly the port pin output will be complimented each time.

4.3 TRIAC :

TRIAC : Structures and Symbols :

The TRIAC can consider a tight relative of the SCR and particularly is adapted to work with the alternating current. Its inner physical structure is analogues to that one of the controlled diode valve, but its three electrodes, rather than to call anode-cathode-gate, as happens in diode valve SCR, comes calls to you, respective, anode ` - anode 2 – gate, like clearly indicated in the design of figure 3, that it proposes the symbol electrical worker of such component.

TWO DIODE VALVES

Fig. Symbol electrical works of the TRIAC, within which to diode valves are visible, connects to you in ant parallel. II component is equipped of two anodes (A1-A2) and of the electrode of gate (G)

Also for the TRIAC two common outer expressions much in commerce exist, those brought back in figure 4, that they are absolutely equal to those of figure 2 and that, just for this reason, can generate, in the mind of the hobbyist, one great confusion. That he changes is the practical application of these components and the denomination of their electrodes.

Operating of the TRIAC

In figure the theoretical application of a TRIAC, analogues is brought back to that one of the SCR of figure.

Fig: Example of employment of a TRIAC, as electronic switch, in a circuit of ignition of one lamp fed in alternating current (C.A.)

In absence of tension impulse that in this case, with the exception of how much it happens in the SCR can be is positive that negative, the TRIAC does not lead, that is behaved as an open switch and lamp LP remains extinguished. Applying instead one small tension, positive or negative, on the gate ones, the TRIAC becomes conductor and is equivalent to a closed switch. But this time the semiconductor lets to cross from both the semi waves of the alternated tension, as it indicates the design of figure.

Fig: Since in the TRIAC two diode are contained connect to you in ant parallel, all the semi waves, those positive ones and those negatives of the alternating current cross the semiconductor.

And that because the inner structure of the TRIAC is correspondent to that one of two diode SCR connects to you in parallel, with the polarity opposite in ant parallel. But with the electrode of I prime in common.

We have said that the TRIAC can be primed applying a tension impulse on its gate ones. But this auto innesca component when the value of the tension alternated applied on the two anodes exceeds a sure limit, called tension of breakdown. Making then to diminish the current and to increase the cargo resistance of the TRIAC, a point is caught up in which the current it is not more in a position to maintaining in conditions the semiconductor.

The minimal value of the current that can maintain primed the TRIAC comes commonly indicated like current of Hold, that is maintenance current.

POWER SUPPLY

5.1 Circuit Description :

The resistors in the AC portion of the circuit amount to 1100 ohms in total. This is made up of R1 plus the 100 ohm fusible resistor. R1 limits the peak current through the capacitor’ but it has very little effect on the RMS current flowing through the circuit – because the contribution of R to the denominator is relatively insignificant.

There’s no inductance to worry about, so

Thus the main control on the current is C1. Its capacitive reactance is given by the formula :-

At 50Hz the capacitive reactance of a 0.47 uf capacitor is about 6k8.

The power dissipated by the 0.47uF capacitor is lower than the power dissipated by a 6k8 resistors, because the current flowing through it. When both the voltage and the current are at maximum, the power reaches its peak.

But the opposite happens with a capacitor. When the voltage across the capacitor is zero, the current through it is at its maximum. At this point the power dissipated by the capacitor is :

Watts =Current x Zero = Zero

Similarly, when the voltage across the capacitor is at its maximum, the capacitor is fully charged ; so the current flowing through it is zero. At this point the power dissipated by the capacitor is :

Watts = Zero x Voltage = Zero

It’s only somewhere between these two extremes – when both the voltage and the current are below their maximum – that the power reaches its peak. Consequently, this peak has to be lower than that of the resistor. Looking at the Transformer less Power Supply- the AC current flowing through the 16v Zener diodes is approximately.

The 33mA current flowing through ZDI & ZD2 is available for rectification. You can think of these Zeners as the secondary windings of a mains transformer. However – unlike a transformer – under ‘no-load conditions’ the Zeners will be required to dissipate the whole of the energy available. Consequently, if your circuit is to be powered up without R2 x ZD3 or the Output Load attached, ZD1 & ZD2 will need to be at least 1-watt.

The Cmos control circuits did not need a particularly smooth supply, and the choice of 47uF for C2 gave a good compromise between physical size and the degree of smoothing. If you have room – and you want more smoothing – then you can use a larger value capacitor.

The output from BRI is about 15-volts. If we want to reduce this to 12-volts using ZD3 then there must be a drop of 3-votls across R2. There is approximately 33m A flowering through ZD1 &ZD2. We cannot try to take more than this from BR1 because it would simply cause a drop in voltage.

So we choose R2 to pass a current of say 30m A.

The 30mA flows through ZD3; and is – in theory – available to power your circuit. If your circuit only needs about 20mA then the remaining 10mA continues to flow through ZD3 so that the voltage drop cross R2 remains constant and the output stays at 12-volts.

If you try to take more than 30mA from the circuit then the voltage drop across R2 will increase beyond 3-volts, and the output will fall below 12-volts. In practice, up to 20mA at 12-volts is available, and another electrolytic capacitor across the output would give additional smoothing if required.

C1 must be a “suppressor” capacitor. They are made to be connected directly across the incoming mains supply. They are generally covered with the logos of many different Safety Standards Athorities.

The larger the value of C1, the lower will be its capacitive reactance, so the higher will be the current flowing through it. You can use a single capacitor with a higher value, or you can connect two or more smaller capacitor in parallel. For example, two 0.47uF capacitor connected in parallel will give the equivalent of a 1uF capacitor – and almost double the available current.

However, increasing the value of the capacitor also increases the significance of the contribution R makes to the denominator –R1 has to work harder’ and the extra current flowing in the circuit means that the resistors and Zener diodes will have to dissipate more energy (Watts).

If C1 equals 1uF then R1 needs to be 7 watts, and the 16-Volt Zeners need to be 2 watts. This brings us to the circuit’s main limitation. It’s really at its best when it’s used to provide up to about 20mA DC. If you try to produce any more current, the components start to get very big. There comes a point when it makes more sense to use a mains transformer.

5.2 Power Supply Diagram :

5.3 Hardware Explanation :

Ic TSOP 1738 converts infrared signals into electrical signals. These signal are applied to microcontroller Ic AT89C2051. It is a programmed by keil software. It receives electrical signals from IR receiver and perform corresponding action. If bulb is already on, make it off and vice versa. This action can be done by using traic Ic BT136. When gate signal is applied triac becomes to off. It button press1, 1^st bulb becomes on, if already on, goes to off. Power on button is used to make all loads to either on or off.

For controlling speed of fan can be done using TRIAC BT 136. By using phase controlling technique, can vary ac voltage. For this method zero cross over detection is used. This can be done using simple transistor BC548 (NPN type). After detecting zero cross over point, depends on speed vary firing angle, then ac voltage varies. So speed of fan also varies. By varying volume + or volume – buttons are used to increase / decrease speed of fan.