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Embedded Systems Seminar On  Applications of Embedded systems Submitted By: Abhishek Vijayvargiya 2bv09ee003 Arjun Sanu 2bv09ee011 Jitesh Emmanuel 2bv09ee021 Kanoj.B 2bv09ee022

Abhi Arjun Jitesh Kanoj

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  • 7/31/2019 Abhi Arjun Jitesh Kanoj


    Embedded Systems



    Applications of

    Embedded systems

    Submitted By:

    Abhishek Vijayvargiya 2bv09ee003

    Arjun Sanu 2bv09ee011

    Jitesh Emmanuel 2bv09ee021Kanoj.B 2bv09ee022

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    The MODEM

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    About MODEM

    Architecture of MODEM

    Whats embedded in there?


    Li-Fi- The future of Ultra Speed Data Transfer

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    About MODEM

    MODEM- MOdulator DEModulator

    Is an electronic device that converts computer's digital information

    into analog carrier signals and vice versa

    Modulation- is the process of changing the form of the signal

    carrying the information.

    Demodulation-is process of extracting information from the

    signals that are modulated.

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    Different Types Of Modems

    Modems are classified on the basis of different criteria such as the

    place where they are installed, the manner in which they accept

    information and the way they transmit signals. Based on these

    criteria, modems are divided into the following types.

    Internal and External Modems:

    Internal modems are in the form of circuit boards, fitted in

    expansion slots of the motherboard. An internal modem is a device

    installed inside a desktop or laptop computer, allowing the

    computer to communicate over a network with other connected

    computers. There are two types of internal modems: dial-up and

    WiFi (wireless). Dial-up operates over a telephone line and

    requires a network access phone number and logon credentials to

    make a connection. WIFI connect wirelessly and without credentials

    in certain cases.

    External modems are enclosed in separate cases and not inside thesystem units. The modem is connected to the computer and telephone

    line by means of two separate cables. Intelligent and Standard

    Modems: Standard Modems: Most modems used today are called standard

    modems. These modems are usually operated by commands entered from

    a microcomputer keyboard. Users control the functions (dialing,

    etc.) of a modem through the keyboard. Modems may use different

    command languages to control their functions, but most modems

    (called "Hayes compatible") use a popular language developed by a

    company "Hayes Microcomputer Products, Inc." Intelligent Modems:Intelligent modems are also called advanced modems. These modems

    can accept new instructions and then respond to the commands while

    transmitting data and information. These can be done by

    microprocessor chips and internal read only memory (ROM) contained

    in the modem.Wireless and Short-Haul Modems: Short-Haul Modems:

    Short- haul modems are devices that transmit signals down the cable

    through any COM1 port. They sometimes are called modem eliminators,

    because they do not require an external power source. They are also

    called line drivers that can send data for a distance of more than

    one mile. This type of modem can be used within or across several

    buildings in a company or a university campus.Wireless Modems:

    Wireless modems transmit the data signals through the air instead

    of by using a cable. They sometimes are called a radiofrequency

    modem. This type of modem is designed to work with cellular

    technology, and wireless local area networks. Wireless modems are

    not yet perfected, but the technology is rapidly improving.

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    The Internal Architecture

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    All the functions of modem are controlled and monitored by logic

    control block. It has the following modules.

    Baud rate generator

    Clock generator

    Handshaking logic

    Tone detector

    Data compression & error detection

    Hayes command set

    Baud rate generator:

    Baud rate is nothing but modulation rate. It is expressed in

    terms of symbols per second or pulses per second. This

    transmission/reception rate is determined by baud rate generator.

    For example: bd1000=1000 pulse/sec.

    Clock generator:

    This circuit produces timing signals which helps in synchronizing the

    circuit operation. It is usually a quartz piezoelectric oscillator &

    may consist of resonant circuit & an amplifier.

    Handshaking logic:

    It is a hardware/software logic wherein signals are transmitted

    back and forth over a communication network in order to maintain thevalid connection or synchronization. There are two types of

    handshaking protocols and they are:-

    Simple handshaking protocol: Here the receiver sends message to


    For eg.: The receiver may send message to sender saying I have

    received our previous message & Im ready for you to send me the

    next message.

    Complex handshaking protocol: Here the sender may ask the receiver

    or receiver may reply the sender.For eg.: The sender asks receiver if he is ready to receive or

    receiver replies with I did not receive your last message

    correctly. Please send it again. (if the data was corrupted in


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    Tone detector:

    Modem requires a channel which should be very clear. Therefore

    it uses echo cancellation. But if the network is also performing the

    echo cancellation, then the two cancellers end up in quarreling,

    leading to bad results. Therefore to avoid this tone detector is used

    which disables the echo cancellation of network.

    Data compression & error detection:

    Data compression enables information to be transmitted beyond

    the actual connection speed. Data, particularly text & graphics

    usually contain repeated sequence of identical information. Data

    compression works by replacing many characters of repeated

    information with few characters & transmitting only one copy of

    repeated sequence of data.

    While transferring data using modem, accidents can & do happen.

    Because of noise the modem may misinterpret the signal receivedfrom other modem causing data corruption. To avoid this Microcosm

    Network Protocol(MNP) is used.

    Hayes command set:

    It is a command language. It consists of series of short text

    strings which combine together to produce complete commands for

    operations like dialing & changing the parameters of the connection.

    Most of the modem use this command set.

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    Functions of MODEM

    Error Correction: Checks whether the data received is undamaged.


    Divides the data into packets called frames.

    Tags each packet with checksum to check redundancy.

    Checks whether the data received is the same as sent.

    Compressing data: The data is compressed & sent in bits over thenetwork.

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    Whats embedded in there ?



    Number Component

    1 SOC processor

    2 Pseudo-static RAM

    3 Serial to Ethernet SOC

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    1. SoC processor

    SoC with highly integrated display, media & imageprocessing.

    ARM processor; 32-bit Reduced Instruction Set

    Computer(RISC) instruction set architecture. Most of

    the instructions are single machine cycle


    Integrated Ethernet Memory Access Control(MAC).

    USB 2.0 host for pc connectivity.

    Device ports to support 3G, WiFi, Bluetooth for

    enhanced data connection.

    Integrated Stereo Class-D amplifier with speaker.

    1080p Hardware Video engine for rich video quality.

    2. PSRAM- Pseudo-Static RAM

    Similar to Static RAM.

    Combined features of DRAM & SRAM

    Inexpensive because of use of DRAM cell array

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    3. Integrated Serial-to-Ethernet SoC

    8051 CPU 64KB ROM

    32KB of SRAM

    2 channel 8bit ADC

    10/100Mbps Ethernet and UART

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    When a modem first makes a connection, we hear screeching sounds

    coming from the modem. These are digital signals coming from the

    computer to which we are connecting being modulated into audible

    sounds. The modem sends a higher-pitched tone to represent the digitI and a lower-pitched tone to represent the digit 0.

    At the other end of the modem connection, the computer attached to

    its modem reverses this process. The receiving modem demodulates the

    various tones into digital signals and sends them to the receiving

    computer. Actually, the process is a bit more complicated than

    sending and receiving signals in one direction and then another.

    Modems simultaneously send and receive signals in small chunks. The

    modems can tell incoming from outgoing data signals by the type of

    standard tones they use.

    Another part of the translation process involves transmission

    integrity. The modems exchange an added mathematical code along the

    way. This special code, called a checksum, lets both computers know

    if the data segments are coming through properly. If the mathematical

    sums do not match, the modems communicate with each other by

    resending the missing segments of data. Modems also have special

    circuitry that allows them to compress digital signals before

    modulating them and then decompressing them after demodulating the

    signals. The compression/decompression process compacts the data so

    that it can travel along telephone lines more efficiently.

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    300 bps modem

    Uses frequency shift keying (FSK)


    Originating Modem : 0 for 1070 Hz tone

    1 for 1270 Hz tone

    Answering Modem : 0 for 2025 Hz tone

    1 for 2225 Hz tone

    Full-duplex operation

    56K modem

    Phase-shift keying(PSK)

    Quadrature amplitude modulation (QAM)

    Asymmetric Digital Subscriber Line( ADSL)

    Bandwidth Range from 24 KHz to 11 Mhz

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    Wi-Fi R & D in RTOS system has resulted in development of Wireless


    Embedded Wi-Fi Modules with RTOS provide simple means of

    wirelessly enabling any device

    These modules communicate via internet

    Since the data transfer happens wirelessly, the serial data

    transfer bus is not present

    The hardware required is complex as the clock signals are

    required to be synchronized wirelessly

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    Large chunks of data are sent through light waves

    Where a Wi-Fi gives data transfer rates of 10-100 Mbps, Li-

    Fi supports data transfer upto 1 Gbps

    The RTOS enabled embedded system has helped in unleashingwhats called as what you see is what you send trend


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    Wikipedia articles about modem


    www.crm.mb.ca/guide/components/modem.html http://www.avnet-