Firstly we would like to heartfully thank our beloved lecturer Mr. M. J. Sampath kumar and Mr. S. B. Rudraswamy without whose guidance our project would have been a mere dream. We also like to take this opportunity to thank our respected HOD C. R. Venugopal. We are grateful to Mr. Yathish and Mar. Suhas, whose guidance and timely support helped us complete this project on time.
For accessing the door latch, transmitter is a mobile through which user can enter the password. The receiving system has a mobile, DTMF decoder, a micro controller (Atmel Atmega 16) which controls the access of door using two motors. In case, the intruder tries to breach into the house through some other means, his motion is being caught by the PIR sensor which is effectively made active during night time with LDR. The motion is stuttered by the voice alarm which will be played in the house keepers reign so that he can take some precautionary measure to buzz him off.
Components used and design criterion: The lists of components used are as follows Design criterion: 1. 2 Block diagram: 3 IC 89S52- Microcontroller: 3. 1 Description: The Atmel Atmega 16 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of in-system programmable Flash memory. The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the industry-standard 80C51 instruction set and pinout. 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 in-system programmable Flash on a monolithic chip, the Atmel Atmega16 is a powerful microcontroller which provides a highly-flexible and cost-effective solution to many embedded control applications. The atnega16 provides the following standard features: 8K bytes of Flash, 256 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, three 16-bit timer/counters, a six-vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator, and clock circuitry.
In addition, the Atmega 16 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. The pin diagram of 89S52 is shown in figure 6. Figure 6:Pin diagram of AT89S52 Pin Descriptions VCC: Digital supply voltage. GND: Ground. Port A (PA7-PA0): Port A serves as the analog inputs to the A/D Converter.
Port A also serves as an 8-bit bi-directional I/O port, if the A/D Converter is not used. Port pins can provide internal pull-up resistors (selected for each bit). The Port A output buffers have symmetrical drive characteristics with both high sink and source capability. When pins PA0 to PA7 are used as inputs and are externally pulled low, they will source current if the internal pull-up resistors are activated. The Port A pins are tri-stated when a reset condition becomes active, even if the clock is not running. Port B (PB7-PB0): Port B is an 8-bit bi-directional I/O port with internal ull-up resistors (selected for each bit).
The Port B output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port B pins that are externally pulled low will source current if the pull-up resistors are activated. The Port B pins are tri-stated when a reset condition becomes active, even if the clock is not running. Port B also serves the functions of various special features of the ATmega16 as listed. Port C (PC7-PC0): Port C is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit).
The Port C output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port C pins that are externally pulled low will source Current if the pull-up resistors are activated. The Port C pins are tri-stated when a reset condition becomes active, even if the clock is not running. If the JTAG interface is enabled, the pull-up resistors on pins PC5 (TDI), PC3 (TMS) and PC2 (TCK) will be activated even if a reset occurs. Port C also serves the functions of the JTAG interface. Port D (PD7-PD0) : Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit).
The Port D output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port D pins that are externally pulled low will source current if the pull-up resistors are activated. The Port D pins are tri-stated when a reset condition becomes active, even if the clock is not running. Port D also serves the functions of various special features of the ATmega16 as listed. RESET: Reset Input. A low level on this pin for longer than the minimum pulse length will generate a reset, even if the clock is not running. The minimum pulse length is given.
Shorter pulses are not guaranteed to generate a reset. XTAL1: Input to the inverting Oscillator amplifier and input to the internal clock operating circuit. XTAL2: Output from the inverting Oscillator amplifier. AVCC: AVCC is the supply voltage pin for Port A and the A/D Converter. It should be externally connected to VCC, even if the ADC is not used. If the ADC is used, it should be connected to VCC through a low-pass filter. AREF: AREF is the analog reference pin for the A/D Converter. 3. 2
The micro-controller program is as follows 2. Details of the components used: 2. MT8870-DTMF Decoder: The DTMF technique will be discussed in detail and its use illustrated in the application examples which follow. More than 25 years ago the need for an improved method for transferring dialing information through the telephone network was recognized. The traditional method, Dial pulse signaling, was not only slow, suffering severe distortion over long wire loops, but required a DC path through the communications channel. A signaling scheme was developed utilizing voice frequency tones and implemented as a very reliable alternative to pulse dialing.
This scheme is known as DTMF (Dual Tone Multi- Frequency), Touch-Tone™ or simply, tone dialing. As its acronym suggests, a valid DTMF signal is the sum of two tones, one from a low group (697-941Hz) and one from a high group (1209-1633Hz) with each group containing four individual tones. The tone frequencies were carefully chosen such that they are not harmonically related and that their intermodulation products result in minimal signaling impairment. This scheme allows for 16 unique combinations. Ten of these codes represent the numerals zero through nine, the remaining six (*, #, A, B, C, D) being reserved for special signaling.
Most telephone keypads contain ten numeric push buttons plus the asterisk (*) and octothorp (#). The buttons are arranged in a matrix, each selecting its low group tone from its respective row and its high group tone from its respective column. The DTMF coding scheme ensures that each signal contains one and only one component from each of the high and low groups. This significantly simplifies decoding because the composite DTMF signal may be separated with band pass filters, into its two single frequency components each of which may be handled individually.
As a result DTMF coding has proven to provide a flexible signaling scheme of excellent reliability, hence motivating innovative and competitive decoder design. Development Early DTMF decoders (receivers) utilized banks of band pass filters making them somewhat cumbersome and expensive to implement. This generally restricted their application to central offices (Telephone exchanges). The first generation receiver typically used LC filters, active filters and/or phase locked loop techniques to receive and decode DTMF tones. Initial functions were commonly, phone number decoders and toll call restrictors.
A DTMF receiver is also frequently used as a building block in a tone-to-pulse converter this allows Touch-Tone dialing access to mechanical step-by-step and crossbar exchanges. The introduction of MOS/LSI digital techniques brought about the second generation of tone receiver development. These devices were used to digitally decode the two discrete tones that result from decomposition of the composite signal. Two analog band pass filters were used to perform the decomposition. Totally self-contained receivers implemented in thick film hybrid technology depicted the start of third generation devices.
Typically, they also used analog active filters to band split the composite signal and MOS digital devices to decode the tones. The development of silicon-implemented switched capacitor sampled filters marked the birth of the fourth and current generation of DTMF receiver technology. Initially single chip band pass filters were combined with currently available decoders enabling a two chip receiver design. A further advance in integration has merged both functions onto a single chip allowing DTMF receivers to be realized in minimal space at a low cost.
The second and third generation technologies saw a tendency to shift complexity away from the analog circuitry towards the digital LSI circuitry in order to reduce the complexity of analog filters and their inherent problems. Now that the filters themselves can be implemented in silicon, the distribution of complexity becomes more a function of performance and silicon real estate. Inside The MT8870 is a state of the art single chip DTMF receiver incorporating switched capacitor filter technology and an advanced digital counting/ averaging algorithm for period measurement. The block diagram illustrates the internal workings of this device.
To aid design flexibility, the DTMF input signal is first buffered by an input op-amp which allows adjustment of gain and choice of input configuration. The input stage is followed by a low pass continuous RC active filter which performs an antialiasing function. Dial tone at 350 and 440Hz is then rejected by a third order switched capacitor notch filter. The signal, still in its composite form, is then split into its individual high and low frequency components by two sixth order switched capacitor and pass filters. Each component tone is then smoothed by an output filter and squared up by a hard limiting comparator.
The two resulting rectangular waves are applied to digital circuitry where a counting algorithm measures and averages their periods. An accurate reference clock is derived from an inexpensive external 3. 58MHz colourburst crystal. The timing diagram illustrates the sequence of events which follow digital detection of a DTMF tone pair. Upon recognition of a valid frequency from each tone group the Early Steering (ESt) output is raised. The time required to detect the presence of two valid tones, tDP, is a function of the decode algorithm, the tone frequency and the previous state of the decode logic.
ESt indicates that two tones of proper frequency have been detected and initiates an RC timing circuit. If both tones are present for the minimum guard time, tGTP, which is determined by the external RC network, the DTMF signal is decoded and the resulting data is latched in the output register. The Delayed Steering (StD) output is raised and indicates that new data is available. The time required to receive a valid DTMF signal, tREC , is equal to the sum of tDP and tGTP. 2. 2 Pin out configuration: Figure 3: Pin out diagram of MT8870 2. 3 Pin description:
Table 1: Pin description of MT8870 Figure 3: the DTMF keypad 2. 4 DTMF output truth table: Table 2: DTMF output truth table 2. 5 Functional diagram: Figure 4:MT8870 functional block diagram PIR-based motion detector INTERNAL CIRCUIT DIAGRAM OF PIR SENSOR: In a PIR-based motion detector, the PIR sensor is typically mounted on a printed circuit board which also contains the necessary electronics required to interpret the signals from the chip. The complete circuit is contained in a housing which is then mounted in a location where the sensor can view the area to be monitored.
Infrared energy is able to reach the sensor through the window because the plastic used is transparent to infrared radiation (but only translucent to visible light). This plastic sheet prevents the introduction of dust and insects which could obscure the sensor’s field of view. A few mechanisms have been used to focus the distant infrared energy onto the sensor surface. The window may have Fresnel lenses molded into it. Alternatively, sometimes PIR sensors are used with plastic segmented parabolic mirrors to focus the infrared energy; when mirrors are used, the plastic window cover has no Fresnel lenses molded into it.
A filtering window (or lens) may be used to limit the wavelengths to 8-14 micrometers which is most sensitive to human infrared radiation (9. 4 micrometers being the strongest). The PIR device can be thought of as a kind of infrared ‘camera’ which remembers the amount of infrared energy focused on its surface. Once power is applied to the PIR the electronics in the PIR shortly settle into a quiescent state and energize a small relay. This relay controls a set of electrical contacts which are usually connected to the detection input of an alarm control panel.
If the amount of infrared energy focused on the sensor changes within a configured time period, the device will switch the state of the alarm output relay. The alarm output relay is typically a “normally closed (NC)” relay, also known as a “Form B” relay. A person entering the monitored area is detected when the infrared energy emitted from the intruder’s body is focused by a Fresnel lens or a mirror segment and overlaps a section on the chip which had previously been looking at some much cooler part of the protected area. That portion of the chip is now much warmer than when the intruder wasn’t there.
As the intruder moves, so does the hot spot on the surface of the chip. This moving hot spot causes the electronics connected to the chip to de-energize the relay, operating its contacts, thereby activating the detection input on the alarm control panel. Conversely, if an intruder were to try to defeat a PIR perhaps by holding some sort of thermal shield between himself and the PIR, a corresponding ‘cold’ spot moving across the face of the chip will also cause the relay to de-energize — unless the thermal shield has the same temperature as the objects behind it.
Manufacturers recommend careful placement of their products to prevent false alarms. They suggest mounting the PIRs in such a way that the PIR cannot ‘see’ out of a window. Although the wavelength of infrared radiation to which the chips are sensitive does not penetrate glass very well, a strong infrared source (a vehicle headlight, sunlight reflecting from a vehicle window) can overload the chip with enough infrared energy to fool the electronics and cause a false (non-intruder caused) alarm. A person moving on the other side of the glass however would not be ‘seen’ by the PIR.
They also recommended that the PIR not be placed in such a position that an HVAC vent would blow hot or cold air onto the surface of the plastic which covers the housing’s window. Although air has very low emissivity (emits very small amounts of infrared energy), the air blowing on the plastic window cover could change the plastic’s temperature enough to, onceagain, fool the electronics. PIRs come in many configurations for a wide variety of applications. The most common used in home security systems has numerous Fresnel lenses or mirror segments and has an effective range of about thirty feet.
Some larger PIRs are made with single segment mirrors and can sense changes in infrared energy over one hundred feet away from the PIR. There are also PIRs designed with reversible orientation mirrors which allow either broad coverage (110° wide) or very narrow ‘curtain’ coverage. PIRs can have more than one internal sensing element so that, with the appropriate electronics and Fresnel lens, it can detect direction. Left to right, right to left, up or down and provide an appropriate output signal. In Short, Passive Infrared (PIR) The most frequent use of the PIR sensor is as an ‘area’ sensor.
Whether it is to detect ‘someone moving in the front yard’, or ‘someone moving in the bathroom’, or ‘someone moving through a doorway’, or even ‘someone opened the beer cooler’, it is all technically the same sensor and logic. There is a simple electronic device which is sensitive to ‘heat’, or rather the infrared light that is emitted by warm or hot objects (like humans). In its simplest form, it looks like an old metal transistor with a black plastic’window’ on the top. The ‘logic’ of the PIR sensor is that it must detect ‘significant change’ of the normal level of heat within the ‘field’ of its view.
The circuits that control it must be able to determine what ‘normal’ is, and then close a switch when the normal field changes, as when a human walks in front of it. It must also be able to ‘tolerate’ slow changes within the field, and remember that as the new ‘normal’. This is so that gradual changes like the sunlight changes throughout the day don’t cause a false alarm. This is a standard behaviour of ‘PIR’ type sensors. (There’s a lot more electronics there than just the black window… ) Why does the sensor wear ‘lenses’?
You’ll notice in all three pictures of PIR type sensors on this page, that they all have some sort of plastic ‘lens’ that covers the circuit board and the PIR sensor device. This is a ‘Fresnel’ lens. It ‘pinches’ light that passes thru it. If you hold it to your eye, you can see that there are apparent distinct ‘bars’ of light as you move it across a scene. Some of these bars may be vertical, and some may be horizontally oriented. The lenses that are made for most PIR sensors tend to ‘pinch’ the light such that it is horizontally sensitive.
This means that the Lens/PIR will be more sensitive to motion of a warm body, horizontally ‘across the field of view’. Please note that this means that these sensors are most insensitive to warm bodies moving from a ‘distance’ and directly towards one of these common devices…! What does a motion sensor say? • All motion sensors send an “ON” message when they first see motion. • Most will also send an “OFF” message when motion has not been seen for a set period of time. • Some will continue to send “ON” messages periodically as long as motion continues. Others may only announce the first event, and say nothing again until the area has been quiet for a set period of time.
A Passive Infrared sensor (PIR sensor) is an electronic device which measures infrared light radiating from objects in its field of view. Apparent motion is detected when an infrared source with one temperature, such as a human, passes in front of an infrared source with another temperature, such as a wall. All objects emit what is known as black body radiation. This energy is invisible to the human eye but can be detected by electronic devices designed for such a purpose.
The term ‘passive’ in this instance means the PIR does not emit energy of any type but merely accepts incoming infrared radiation. Design Infrared radiation enters through the front of the sensor, known as the sensor face. At the core of a PIR is a solid state sensor or set of sensors, made from approximately 1/4 inches square of natural or artificial pyroelectric materials, usually in the form of a thin film, out of gallium nitride (GaN), caesium nitrate (CsNO3), polyvinyl fluorides, derivatives of phenylpyrazine, and cobalt phthalocyanine. (See pyroelectric crystals. Lithium tantalate (LiTaO3) is a crystal exhibiting both piezoelectric and pyroelectric properties.
The sensor is often manufactured as part of an integrated circuit and may consist of one (1), two (2) or four (4) ‘pixels’ of equal areas of the pyroelectric material. Pairs of the sensor pixels may be wired as opposite inputs to a differential amplifier. In such a configuration, the PIR measurements cancel each other so that the average temperature of the field of view is removed from the electrical signal; an increase of IR energy across the entire sensor is self-cancelling and will not trigger the device.
This allows the device to resist false indications of change in the event of being exposed to flashes of light or field-wide illumination. (Continuous bright light could still saturate the sensor materials and render the sensor unable to register further information. ) At the same time, this differential arrangement minimizes common-mode interference; this allows the device to resist triggering due to nearby electric fields. However, a differential pair of sensors cannot measure temperature in that configuration and therefore this configuration is specialized for motion detectors.
Light detecting resistor(LDR): CIRCUIT DIAGRAM OF LDR: A photo resistor or light dependent resistor (LDR) is a resistor whose resistance decreases with increasing incident light intensity. It can also be referred to as a photoconductor. A photo resistor is made of a high resistance semiconductor. If light falling on the device is of high enough frequency, photons absorbed by the semiconductor give bound electrons enough energy to jump into the conduction band. The resulting free electron (and its hole partner) conduct electricity, thereby lowering resistance.
A photoelectric device can be either intrinsic or extrinsic. An intrinsic semiconductor has its own charge carriers and is not an efficient semiconductor, e. g. silicon. In intrinsic devices the only available electrons are in the valence band, and hence the photon must have enough energy to excite the electron across the entire bandgap. Extrinsic devices have impurities, also called dopants added whose ground state energy is closer to the conduction band; since the electrons do not have as far to jump, lower energy photons (i. e. longer wavelengths and lower frequencies) are sufficient to trigger the device. If a sample of silicon has some of its atoms replaced by phosphorus atoms (impurities), there will be extra electrons available for conduction.
This is an example of an extrinsic semiconductor. Photo resistors come in many different types. Inexpensive cadmium sulfide cells can be found in many consumer items such as camera light meters, street lights, clock radios, alarms, and outdoor clocks. They are also used in some dynamic compressors together with a small incandescent lamp or light emitting diode to control gain reduction.
Lead sulfide (PbS) and indium antimonide (InSb) LDRs (light dependent resistor) are used for the mid infrared spectral region. Ge: Cuphotoconductors are among the best far-infrared detectors available, and are used for infrared astronomy and infrared spectroscopy. Voice recording and playback: Digital voice processing chips with different features and coding techniques for speech compression and processing are available on the market from a number of semiconductor manufacturers.
Advanced chips such as Texas instruments’ TMS320C31 can implement various voice-processing algorithms including code-excited linear prediction, adaptive differential pulse-code modulation, A law specified by California Council for International Trade), ? law (specified by Bell Telephone) and vector sum- excited linear prediction . On the other hand, APR9600 single chip voice recorder and playback device from Aplus Integrated Circuits. Fig. 1 shows the functional block diagram of IC APR9600. Complete chip management is accomplished through the device control and message control blocks. Voice signal from the icrophone (see Fig. 2) is fed into the chip through a differential amplifier. It is further amplified by connecting Ana_Out (pin 21) to Ana_In (pin 20) via an external DC blocking capacitor C1. A bias signal is applied to the microphone and to save power during playback, the ground return of this bias network can be connected to the normally open side of the record switch. Both Mic. in and Mic. Ref (pins 18 and 19) must be coupled to use of a proprietary analogue storage technique implemented using flash non volatile memory process in which each cell is capable of storing up to 256 voltage levels.
This technology enables the APR9600 to reproduce voice signals in their natural form. The APR9600 is a good standalone voice recorder or playback IC with non volatile storage and playback capability for 32 to 60 seconds. It can record and play multiple messages at random or in sequential mode. The user can select sample rates with consequent quality and recording time trade-off. Microphone amplifier, automatic gain control (AGC) circuits, internal anti-aliasing filter, integrated output amplifier and messages management are some of the features of the APR9600 chip.