Microcontroller.docx

MICROCONTROLLER



small computer on a single integrated circuit containing a CPU,

memory,

Timer

and

It

is

a

programmable

input/output ports 

Microcontroller available with different word length such as 8bit, 16bit and 32 bits microcontroller



Microcontroller can contain a varying number of I/O pins. These pins can configured to either an input or an output state. A microcontroller is a small computer (SoC) on a

single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Program memory in the form of Ferroelectric RAM, NOR flash or OTP ROM is also often included on chip, as well as a typically small amount of RAM. Microcontrollers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general purpose applications consisting of various discrete chips. Microcontrollers are used in automatically controlled products and devices, such as automobile engine control systems, implantable medical devices, remote controls, office machines, appliances, power tools, toys and other embedded systems. By reducing the size and cost compared to a design that

uses

a

separate

microprocessor,

memory,

and

input/output devices, microcontrollers make it economical to digitally control even more devices and processes. Mixed signal microcontrollers are common, integrating analog components needed to control non- digital electronic systems. Some microcontrollers may use four-bit words and operate at clock rate frequencies as low as 4 kHz, for low power

consumption (single-digit milli watts or microwatts). They will generally have the ability to retain functionality while waiting for an event such as a button press or other interrupt; power consumption while sleeping (CPU clock and most peripherals off) may be just nano watts, making many of them well suited for long lasting battery applications. Other microcontrollers may serve performance-critical roles, where they may need to act more like

a digital signal processor (DSP), with higher

clock speeds and power consumption.

Microcontroller embedded memory technology Since the emergence of microcontrollers, many different memory

technologies

have

been

used.

Almost

all

microcontrollers have at least two different kinds of memory, a non-volatile memory for storing firmware and a read-write memory for temporary data. Data working transistors

per

memory, bit

used

with in

a

few

more

the register file. FRAM or

MRAM could potentially replace it as it is 4 to 10 times denser which would make it more cost effective.

In addition to the SRAM, some microcontrollers also have internal EEPROM for data storage; and even ones that do not have any (or not enough) are often connected to external serial EEPROM chip (such as the BASIC Stamp) or external serial flash memory chip. A few recent microcontrollers beginning in From the earliest microcontrollers to today, six- transistor SRAM is almost always used as the read/write 2003 have "selfprogrammable" flash memory. Firmware The earliest microcontrollers used mask ROM to store firmware. Later microcontrollers (such as the early versions of the Frees cale 68HC11 and early PIC microcontrollers) had quartz windows that allowed ultraviolet light in to erase the EPROM. The Microchip PIC16C84, introduced in 1993,was the first microcontroller to use EEPROM to store firmware. In the same year, Atmel introduced the first microcontroller NOR Flash memory to store firmware.

STEPPER MOTOR



Stepper motors are digital motors, we actually Send Position signals to the Motor to drive them.



It is of four wire stepper motor A stepper motor or step motor or stepping motor is

a motor that divides a full rotation into a number of equal steps. The motor's position can then be commanded to move and hold at one of these steps without any feedback sensor (an

open-loop controller), as long as the motor is carefully sized to the application in respect to torque and speed. Switched reluctance motors are very large stepping motors with a reduced pole count, and generally are closedloop commutated. APPLICATIONS Computer controlled stepper motors are a type of motion-control positioning system. They are typically digitally controlled as part of an open loop system for use in holding or positioning applications. In the field of lasers and optics they are frequently used in precision positioning equipment such as linear actuators, linear stages, rotation stages, goniometers and mirror mounts. Other uses are in packaging machinery, and positioning of valve pilot stages for fluid control systems. Commercially, stepper motors are used in floppy disk drives, flatbed

scanners, computer printers, plotters, slot

machines image scanners, compact disc drives, intelligent lighting, camera lenses, CNC machines and, more recently, in 3D printers.

Stepper motor system A stepper motor system consists of three basic elements, often combined with some type of user interface (host computer, PLC or dumb terminal):



Indexers - The indexer (or controller) is a microprocessor capable of generating step pulses and direction signals for the driver. In addition, the indexer is typically required to perform many other sophisticated command functions.



Drivers - The driver (or amplifier) converts the indexer command signals into the power necessary to energize the motor windings. There are numerous types of drivers, with different voltage and current ratings and construction technology. Not all drivers are suitable to run all motors, so when designing a motion control system the driver selection process is critical.



Stepper motors - The stepper motor is an electromagnetic device that converts digital pulses into mechanical shaft rotation. Advantages of step motors are low cost, high reliability, high torque at low speeds and a simple, rugged construction that operates in almost any environment. The main disadvantages in using a stepper motor is the resonance decreasing

effect

often

torque

exhibited with

at

low

speeds

increasing

and

speed.

Advantages 

Low cost for control achieved



High torque at startup and low speeds



Ruggedness



Simplicity of construction



Can operate in an open loop control system



Low maintenance



Less likely to stall or slip



Will work in any environment



Can be used in robotics in a wide scale.



High reliability

Disadvantages 

Require a dedicated control circuit



Use more current than D.C. motors



Torque reduces at higher speeds



Resonances can occur if not properly controlled.



Not easy to operate at extremely high speeds.

PIR SENSOR

A passive infrared sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used in PIR-based motion detectors. PIR sensor allow us to sense the motion, almost Always use to detect whether a human has moved in or out of the sensors range. It is commonly found in appliances and gadgets Used in homes or business, Sensitivity Range: up to 20 feet (6 meters). We, homo sapiens, radiate heat in form of radiation at wavelength of 10-12 micrometer that can only detect by the PIR sensor .

PIR sensors allow you to sense motion, almost always used to detect whether a human has moved in or out of the sensors range. They are small, inexpensive, lowpower, easy to use and don't wear out. OPERATING PRINCIPLES All objects with a temperature above absolute zero emit heat energy in the form of radiation. Usually this radiation is invisible to the human eye because it radiates at infrared wavelengths, but it can be detected by electronic devices designed for such a purpose. The term passive in this instance refers to the fact that PIR devices do not generate or radiate any energy for detection purposes. They work entirely by detecting the energy given off by other objects.[1] PIR sensors don't detect or measure "heat"; instead they detect the infrared radiation emitted or reflected from an object. CONSTRUCTION Infrared radiation enters through the front of the sensor, known as the 'sensor face'. At the core of a PIR sensor is a solid state sensor or set of sensors, made from materials which generate energy when exposed to heat. Typically, the sensors are approximately 1/4 inch square (40 mm2), and take

the form of a thin film. Materials commonly used in PIR sensors

include gallium

nitride (GaN), caesium nitrate

(CsNO3), polyvinyl fluorides, derivatives of phenylpyridine , and cobalt phthalocyanine. The sensor is often manufactured as part of an integrated circuit. A

PIR-based

motion

detector

is

used

to

sense

movement of people, animals, or other objects. They are commonly used in burglar alarms and automatically-activated lighting systems. They are commonly called simply "PIR", or sometimes "PID", for "passive infrared detector". Operation An individual PIR sensor detects changes in the amount of infrared radiation impinging upon it, which varies depending on the temperature and surface characteristics of the objects in front of the sensor. When an object, such as a human, passes in front of the background, such as awall, the temperature at that point in the sensor's field of view will rise from room temperature tobody temperature, and then back again. The sensor converts the resulting change in the incoming infrared radiation into a change in the output voltage, and this triggers the detection. Objects of

similar

temperature

but

different

surface

characteristics may also have a different infrared emission pattern, and thus moving them with respect to the background may trigger the detector as well. PIRs come in many configurations for a wide variety of applications. The most common models have numerous Fresnel lenses or mirror segments, an effective range of about ten meters (thirty feet), and a field of view less than 180 degrees. Models with wider fields of view, including 360 degrees, are available—typically designed to mount on a ceiling. 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, or with individually selectable segments to "shape" the coverage.

GSM MODEM



It is a special type of modem which accepts SIM card.



These

GSM

modem

are

more

used

frequently

to

provide

mobile connectivity. 

Many of them can also be used for sending and receiving SMS.



In this case we are using GSM modem for sending the message only.

GSM was intended to be a secure wireless system. It has considered the user authentication using a pre-shared key and

challenge-response,

and

over-the-air

encryption.

However, GSM is vulnerable to different types of attack, each of them aimed at a different part of the network. The

development

of

UMTS

introduces

an

optional

Universal Subscriber Identity Module (USIM), that uses a longer authentication key to give greater security, as well as mutually authenticating the network and the user, whereas GSM only authenticates the user to the network (and not vice versa). The security model therefore offers confidentiality

and

authentication,

but

limited

authorization capabilities, and no non- repudiation. GSM

uses

security.

several

cryptographic

algorithms

for

The A5/1, A5/2, and A5/3 stream ciphers are

used for ensuring over-the-air voice privacy. A5/1 was developed first and is a stronger algorithm used within Europe and the United States; A5/2 is weaker and used in other countries. Serious weaknesses have been found in both algorithms: it is possible to break A5/2 in real-time with a ciphertext-only attack, and in January 2007, The Hacker's Choice started the A5/1 cracking project with plans to use FPGAs that allow A5/1 to be broken with a rainbow table attack. The system supports multiple algorithms so operators may replace that cipher with a stronger one. Since 2000, different efforts have been done in order to

crack the A5 encryption algorithms. Both A5/1 and A5/2 algorithms are broken, and their cryptanalysis has been considered in the literature. As an example, Karsten Nohl developed a number of rainbow tables (static values which reduce the time needed to carry out an attack) and have found new sources for known plaintext attacks. He said that it is possible to build "a full GSM

interceptor...from open-source components" but that they had not done so because of legal concerns. Nohl claimed that he was able to intercept voice and text conversations by impersonating another user to listen to voicemail, make calls, or send text messages using a seven-year-old Motorola cell phone and decryption software available for free online. New attacks have been observed that take advantage of poor security implementations, architecture, and development for smart phone applications. Some wiretapping and eavesdropping techniques hijack the audio input and output providing an opportunity for a third party to listen in to the conversation. GSM uses General Packet Radio Service (GPRS) for data transmissions like browsing the web. The most commonly deployed GPRS ciphers were publicly broken in 2011. The researchers revealed flaws in the commonly used GEA/1 and GEA/2 ciphers and published the opensource "gprs decode" software for sniffing GPRS networks. They also noted that some carriers do not encrypt the data (i.e., using GEA/0) in order to detect the use of traffic or protocols they do not like (e.g., Skype), leaving customers unprotected. GEA/3 seems to remain relatively hard to break and is said to be in

use on some more modern networks. If used with USIM to

prevent

connections

to fake

base

stations and downgrade attacks, users will be protected in the medium term, though migration to 128-bit GEA/4 is still recommended. Camera

Wireless security cameras are closed-circuit television (CCTV) cameras that transmit a video and audio signal to a wireless receiver through a radio band. Many wireless security cameras require at least one cable or wire for power; "wireless" refers to the transmission of video/audio. However, some wireless security cameras are

battery-powered, making the cameras truly wireless from top to bottom. Wireless cameras are proving very popular among modern security consumers due to their low installation costs (there is no need to run expensive video extension cables) and flexible mounting options; wireless cameras can

be

mounted/installed

in

locations

previously

unavailable to standard wired cameras. In addition to the ease of use and convenience of access, wireless security camera allows users to leverage broadband wireless internet to provide seamless video streaming over-internet. Digital wireless is the transmission of audio and video analog signals encoded as digital packets over highbandwidth radio frequencies. Advantages include: 

Wide transmission range—usually close to 450 feet (open space, clear line of sight between camera and receiver)



High quality video and audio



Two-way communication between the camera and the receiver



Digital signal means you can transmit commands and functions, such as turning lights on and off.



You can connect multiple receivers to one recording device, such as security DVR

Wireless Range Wireless security cameras function best when there is a clear line of sight between the camera(s) and the receiver. Outdoors, and with clear line of sight, digital wireless cameras typically have a range between 250 to 450 feet. Indoors, the range can be limited to 100 to 150 feet. Cubical walls, drywall, glass, and windows generally do not degrade wireless signal strength. Brick, concrete floors, and walls degrade signal strength. Trees that are in the line of sight of the wireless camera and receiver may impact signal strength. The signal range also depends on whether there are competing signals using the same frequency as the camera. For example, signals from cordless phones or routers may affect signal strength. When this happens, the camera image may freeze, or appear "choppy". Typical solution involves locking the channel that wireless router operates on.

Personal Computer

A

personal

computer

is

a

general-purpose

computer whose size, capabilities, and original sale price make it

useful

for individuals, and is intended to

operated directly by an end-

user with no intervening

computer time-sharing models more

be

that

allowed

larger,

expensive minicomputer and mainframe systems to

be used by many people, usually at the same time. Software computers

applications

include,

but

are

for not

most limited

personal to,

word

processing, spreadsheets,databases, webbrowsers and email

clients,

digital

media

manypersonalproductivityand

playback,

games

and

special-purpose

software applications. Modern personal computers often have connections to the Internet, allowing access to the World Wide Web and a wide range of other resources. Personal computers may be connected to a local area network(LAN), either by a cable or a wireless connection. A personal computer may be a laptop computer or a desktop computer running an operating system

such

as

Windows, Linux

(and

the

various

operating systems based on it), or Macintosh OS. Early computer owners usually had to write their own programs to do anything useful with the machines, which even did not include an operating system. The very earliest microcomputers, equipped with a front panel, required hand-loading of a bootstrap program to load programs from external storage (paper tape, cassettes, or eventually diskettes). Before very long , automatic booting from permanent read-only memory became universal. Today's users have access to a wide range of commercial software, freeware and free and open-source software, which are provided in ready-to-run or ready-to-compile form.

Software

for

personal

computers,

such

as

applications and video games, are typically developed and distributed independently from the hardware or OS

manufacturers, whereas software for many mobile phones and other portable systems is approved and distributed through a centralized online store.[1][2] Since the early 1990s, Microsoft operating systems and Intel hardware dominated much of the personal computer market, first with MS-DOS and then with Windows. Popular alternatives to Microsoft's Windows operating systems include Apple's OS X and free opensource Unix- like operating systems such as Linux and BSD. AMD provides the major alternative to Intel's processors. ARM architecture processors now outnumber Intel's (and compatibles) in smart phones and tablets , that are also personal computers, outnumbering the traditional kind.