embedded system on board communication.pptx

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1. I V . C O M M UN I C A T I O N INTERFACE Prepared by Raghunath M UNIT IV: COMMUNICATION INTERFACE : Need for communication interfaces, RS232 / UART, RS422 / RS485, USB, Infrared, IEEE 1394 Fire wire, Ethernet, IEEE 802.11, Blue tooth.

2. Communication interface are the devices through with the E.S can interact with various subsystems and the external world. For embedded product communication interface can be viewed in two different perspectives : Device/board level communication interface (On board communication Interface) Product level communication interface (External communication interface)

3. Onboard communication Interface The communication channel which interconnects the various components within an embedded product is referred as device/on broad level communication interface. EX: I2C SPI UART I- Wire

4. 1.INTER INTEGRATED CIRCUIT BUS[I2C bus] - contents I2C bus Introduction BUS Lines I2C Protocols I2C related terms Repeated Start Condition Clock Stretching Acknowledge (ACK) and Not Acknowledge (NACK) 10- bit Addresses Advantages of I2C Disadvantages of I2C Applications of I2C

5. INTER INTEGRATED CIRCUIT BUS[I2C bus] It is a synchronous bi- directional half duplex two – wire serial bus which provides communication link between integrated circuits. It was designed by Philips Semiconductors in 1980s. It was developed to provide an easy way of connection between a microprocessor / microcontroller system and low speed peripheral chips/Ic

6. It comprises of two bus lines Serial Clock- SCL and Serial Data- SDA. SCL line is responsible for generating synchronization clock pulses. SDA is responsible for transmitting the serial data across devices. I2C bus is a shared bus system to which many number of I2C devices can be connected. Devices connected to the I2C bus can act as either “Master” device or “Slave” device. The Master device is responsible for controlling the communication by initiating or terminating data transfer, sending data and generating necessary synchronization clock pulses. The Slave devices wait for the commands from the Master and respond upon receiving the commands.

7. Messages are broken up into two types of frame: an address frame , where the master indicates the slave to which the message is being sent, and data frames , which are 8- bit data messages passed from master to slave or vice versa.

8. I2C Protocols: Start Condition: To initiate the address frame, the master device leaves SCL high and pulls SDA low. This puts all slave devices on notice that a transmission is about to start. Address Frame: The address frame is always first in any new communication sequence. For a 7-bit address, the address is clocked out most significant bit (MSB) first, followed by a R/W bit indicating whether this is a read (1) or write (0) operation. The 9th bit of the frame is the NACK/ACK bit. This is the case for all frames (data or address). Once the first 8 bits of the frame are sent, the receiving device is given control over SDA. If the receiving device does not pull the SDA line low before the 9th clock pulse, it can be inferred that the receiving device either did not receive the data or did not know how to parse the message.

9. Data Frames: After the address frame has been sent, data can begin being transmitted. The master will simply continue generating clock pulses at a regular interval, and the data will be placed on SDA by either the master or the slave, depending on whether the R/W bit indicated a read or write operation. Stop condition: Once all the data frames have been sent, the master will generate a stop condition. Stop conditions are defined by a 0->1 (low to high) transition on SCL, with SCL remaining high.

10. I2C related terms: Repeated Start Condition During an I2C communication, sometimes a master wants to send a specific command to a slave device and read back response right away. In this situation there is a possibility that another master (in case of multi- master bus) takes the control of the bus. To avoid these conditions I2C protocol defines repeated start condition. In normal cases I2C master will send start condition, address + R/W bit, send or receive any number of bytes and mark the end by a stop condition. During repeated start condition, master will send START CONDITION instead of stop condition and will keep the control over the bus. Master can send any number of start condition using this method. Irrespective of the number of start conditions, transfer must be end by exactly one stop condition.

11. Clock Stretching: We have seen that master device determines the clock speed in I2C communication. This avoid the need of synchronizing master and slave exactly to a predefined baud rate. But there can be some situations when I2C slave device is not able to cooperate with clock signals given by master. Clock stretching is the mechanism used to slow down master device for slave device to complete it’s operation. I2C slave device is allowed to hold down the clock signal when it needs master to slow down on the 9th clock of every data transfer before the ACK stage. Acknowledge (ACK) and Not Acknowledge (NACK) Each byte of data in I2C communication includes an additional bit known as ACK bit. This bit provides a provision for the receiver to send a signal to transmitter that the byte was successfully received and ready to accept another byte. 10- bit Addresses Generally I2C bus uses 7-bit addressing, which means that devices are limited to 127 devices and address clashes can happen. 10-bit address scheme is introduced to solve this problem. 10-bit address devices can be mixed with 7- bit devices and it increases the address range about 10 times.

12. Advantages of I2C: Needs only 2 lines (SCL & SDA) + Ground as reference Supports up to 1008 slave devices Supports multi- master system Disadvantages of I2C: Needs more complex hardware Data rate less than SPI I2c Applications: EEPROMs Real Time Clock ICs Temperature Sensors Accelerometers Gyro meters LCDs

13. 2.SERIAL PERIPHERAL INTERFACE(SPI BUS) - Contents SPI BUS Introduction The SPI bus Lines SPI Configuration Typical SPI Bus Daisy- Chained SPI Bus SPI Data Transmission SPI Modes –Clock Polarity & Phase Advantages of SPI Disadvantages of SPI Applications of SPI Differences Between I2C and SPI

14. 2.SERIAL PERIPHERAL INTERFACE(SPI BUS) The Serial Peripheral Interface bus (SPI) is a synchronous serial communication interface specification used for short distance communication, primarily in embedded systems. Interface was developed by Motorola in the late 1980s and has become a de- facto standard. SPI devices communicate in full duplex mode using a master- slave architecture with a single master. Sometimes SPI is called a four- wire serial bus

15. The SPI bus specifies four logic signals: SCLK: Serial Clock (output from master) MOSI : Master Output Slave Input, or Master Out Slave In (data output from master). MISO : Master Input Slave Output, or Master In Slave Out (data output from slave). SS : Slave Select (often active low, output from master)

16. SCK (Serial Clock) The SPI used clock signal to synchronize the transfer of data across the SPI interface. The SCK is always driven by the master and received by the slave, The clock is programmable to be active high or active low. The SCK is only active during a data transfer. Any other time, it is either in its inactive state, or tri stated. MISO (Master in Slave out) The MISO signal is a unidirectional signal used to transfer serial data from the the master to slave. When a device is a slave, serial data is output on this signal. When a device is a master, serial data is input on this signal. When a slave device is not selected, the slave drives the signal high impedance

17. MOSI (Master out Slave in) The MOSI signal is a unidirectional signal used to transfer serial data from the slave to the master. •When a device is a Master, serial data is output on this signal. When a device is a Slave, serial data is input on this signal. SSEL(Slave Select) The SPI slave select signal is an active low signal that indicates which slave is currently selected to participate in a data transfer. Each slave has its own unique slave select signal input. The SSEL must be low before data transactions begin and normally stays low for the duration of the transaction. If the SSEL signal goes high any time during a data transfer, the transfer is considered to be aborted. In this event, the slave returns to idle, and any data that was received is thrown away. There are no other indications of this exception

18. SPI Configuration Typical SPI bus: Master and independent Slaves Daisy- Chained SPI bus: Master and cooperative slaves Typical SPI Bus With multiple slave devices, an independent SSEL signal is required from the master for each slave device (3). In the independent slave configuration, there is an independent slave select line for each slave. This is the way SPI is normally used. Since the MISO pins of the slaves are connected together, they are required to be tri- state pins.

19. Daisy- Chained SPI Bus Some products with SPI bus are designed to be capable of being connected in a daisy chain configuration, the first slave output being connected to the second slave input, etc. The SPI port of each slave is designed to send out during the second group of clock pulses an exact copy of what it received during the first group of clock pulses. Such a feature only requires a single SSEL line from the master, rather than a separate SSEL line for each slave

20. SPI Data Transmission A typical hardware setup using two shift registers to form an inter- chip circular buffer To begin a communication, the master first configures the Clock, using a frequency less than or equal to the maximum frequency the slave device supports. The master then pulls the slave select SSEL low for the desired chip. During each SPI clock cycle, a full duplex data transmission occurs The master sends a bit on the MOSI line; the slave reads it from that same line.

21. The slave sends a bit on the MISO line; the master reads it from that same line Transmissions normally involve two shift registers of some given word size, such as eight bits, one in the master and one in the slave; they are connected in a ring. After that register has been shifted out, the master and slave have exchanged values. Then each device takes that value and does something with it, such as writing it to memory If there are more data to exchange, the shift registers are loaded with new data and the process repeats.

22. SPI Modes –Clock Polarity & Phase We already seen that clock for data transfer is generated by the SPI master. So the master should set the clock frequency for SPI transfer. In addition to this clock polarity and clock phase are there, which has to match with SPI slaves for proper data transfer Clock Polarity : CPOL or CKP Clock polarity is the idle / active state of the clock. If idle state is 0, active state will be 1 and vice versa. • Clock Phase :CPHA, Inverted Clock Phase (Clock Edge) : NCPHA or CKE Clock phase or clock edge defines when to transfer data. Data can be transferred during LOW (0) to HIGH (1) or HIGH to LOW transitions.

23. Bits that are sampled on the rising edge of the clock cycle are shifted out on the falling edge of the clock cycle, and vice versa.

24. Each transaction begins when the slave- select line is driven to logic low (slave select is typically an active- low signal). The exact relationship between the slave- select, data, and clock lines depends on how the clock polarity (CPOL) and clock phase (CPHA) are configured. With non-inverted clock polarity (i.e., the clock is at logic low when slave select transitions to logic low): Mode 0: Clock phase is configured such that data is sampled on the rising edge of the clock pulse and shifted out on the falling edge of the clock pulse. This corresponds to the first blue clock trace in the above diagram. Note that data must be available before the first rising edge of the clock. Mode 1: Clock phase is configured such that data is sampled on the falling edge of the clock pulse and shifted out on the rising edge of the clock pulse. This corresponds to the second blue clock trace in the above diagram. With inverted clock polarity (i.e., the clock is at logic high when slave select transitions to logic low): Mode 2: Clock phase is configured such that data is sampled on the falling edge of the clock pulse and shifted out on the rising edge of the clock pulse. This corresponds to the first orange clock trace in the above diagram. Note that data must be available before the first falling edge of the clock. Mode 3: Clock phase is configured such that data is sampled on the rising edge of the clock pulse and shifted out on the falling edge of the clock pulse. This corresponds to the second orange clock trace in the above diagram.

25. Advantages of SPI: Simple hardware Full duplex communication Simple software implementation High Speed No speed limit (practically it will be limited by the clock frequency, rise time, fall time etc.) Not Limited to 8 bit data Signals are unidirectional through all lines, makes easy isolation No need of unique address in slaves like in RS485 or I2C. No need of precision oscillators in slave devices as it uses master’s clock No complex transceivers are required

26. Disadvantages of SPI: More pins/wires are required. Minimum 3 wires (in single slave) are required. Can be used only from short distances • No error detection protocol is defined Usually supports only one master Not have ack mechanism to confirm receipt of data and does not have flow control. SPI Master, not have knowledge of whether slave exist or Not. Not particular addressing scheme. Applications of SPI: SD Cards LCD Displays RTC (real time clocks) Ethernet Controllers

27. Differences Between I2C and SPI

28. 3.universal asynchronous receiver-transmitter (UART) - contents UART Introduction UART communication UART serial communication Rule/conditions of UART serial communication UART Throughput Advantages of UART Disadvantages of UART Applications of UART USART (Universal Synchronous/Asynchronous Receiver/Transmitter) Practical differences between synchronous mode and asynchronous mode

29. 3.universal asynchronous receiver- transmitter (UART) UART stands for Universal Asynchronous Receiver/Transmitter. It’s not a communication protocol like SPI and I2C,but a physical circuit in microcontroller, or a stand- alone IC. It is a computer hardware device for asynchronous serial communication in which data format and transmission speeds are configurable. A UART’s main purpose is to transmit and receive serial data. One of the best things about UART is that it only uses two wires to transmit data between devices

30. UART communication

31. In UART communication, two UARTs communicate directly with each other. The transmitting UART converts parallel data from a controlling device like a CPU into serial form, transmits it in serial to the receiving UART, which then converts the serial data back into parallel data for the receiving device. The UART that is going to transmit data receives the data from a data bus. The data bus is used to send data to the UART by another device like a CPU, memory, or microcontroller. Data is transferred from the data bus to the transmitting UART in parallel form. After the transmitting UART gets the parallel data from the data bus, it adds a start bit, a parity bit, and a stop bit, creating the data packet Next, the data packet is output serially, bit by bit at the Tx pin. The receiving UART reads the data packet bit by bit at its Rx pin. The receiving UART then converts the data back into parallel form and removes the start bit, parity bit, and stop bits. Finally, the receiving UART transfers the data packet in parallel to the data bus on the receiving end UART communication

32. The data in UART serial communication is organized in to blocks called Packets or Frames . UART serial communication

33. START BIT The UART data transmission line is normally held at a high voltage level when it’s not transmitting data. To start the transfer of data, the transmitting UART pulls the transmission line from high to low voltage level. When the receiving UART detects the high to low voltage transition, it begins reading the bits in the data frame at the frequency of the baud rate. DATA FRAME The data frame contains the actual data being transferred. It can be 5 bits up to 8 bits long if a parity bit is used. If no parity bit is used, the data frame can be 9 bits long. In most cases, the data is sent with the least significant bit first

34. PARITY Parity describes the evenness or oddness of a number. The parity bit is a way for the receiving UART to tell if any data has changed during transmission(Bits can be changed by electromagnetic radiation, mismatched baud rates, or long distance data transfers). After the receiving UART reads the data frame, it counts the number of bits with a value of 1 and checks if the total is an even or odd number. If the parity bit is a (even parity), the all bits in the data frame should total to an even number. If the parity bit is a 1 (odd parity), the all bits in the data frame should total to an odd number. When the parity bit matches the data, the UART knows that the transmission was free of errors. But if the parity bit is a 0, and the total is odd; or the parity bit is a 1, and the total is even, the UART knows that bits in the data frame have changed. STOP BITS To signal the end of the data packet, the sending UART drives the data transmission line from a low voltage to a high voltage for at least two bit durations.

35. UART transmitter and receiver must agree on some rules of serial communication for error free transfer of data. The rules include: • Synchronization Bits (Start and Stop bits) • Parity Bit • Data Bits and • Baud Rate Baud Rate The speed at which the data is transmitted is mentioned using Baud Rate. Both the transmitting UART and Receiving UART must agree on the Baud Rate for a successful data transmission. Baud Rate is measured in bits per second(bps) Some of the standard baud rates are 4800 bps, 9600 bps, 19200 bps, 115200 bps etc. Out of these 9600 bps baud rate is the most commonly used one Rule/conditions of UART serial communication

36. UART Throughput 9600 baud means 9600 Hz – 9600 bits per second (bps) Throughput refers to how much data can be transferred from one location to another in a given amount of time

37. Advantages of UART: Requires only two wires for full duplex data transmission (apart from the power lines). No need for clock or any other timing signal. Parity bit ensures basic error checking is integrated in to the data packet frame. Disadvantages of UART: Size of the data in the frame is limited. Speed for data transfer is less compared to parallel communication. Transmitter and receiver must agree to the rules of transmission and appropriate baud rate must be selected Doesn’t support multiple slave or multiple master systems Applications of UART: UART is normally used in microcontrollers for exact requirements, and these are also available in various communication devices like wireless communication, GPS units, Bluetooth module, and many other applications.

38. USART (Universal Synchronous/Asynchronous Receiver/Transmitter) A USART (Universal Synchronous/Asynchronous Receiver/Transmitter) is a microchip that facilitates communication through a computer's serial port using the RS- 232C protocol . Like a UART (Universal Asynchronous Receiver/Transmitter), a USART provides the computer with the interface necessary for communication with modems and other serial devices. However, unlike a UART, a USART offers the option of synchronous mode. In program-to- program communication, the synchronous mode requires that each end of an exchange respond in turn without initiating a new communication. Asynchronous operation means that a process operates independently of other processes

39. Practical differences between synchronous mode (which is possible only with a USART) and asynchronous mode (which is possible with either a UART or a USART) can be outlined as follows. Synchronous mode requires both data and a clock. Asynchronous mode requires only data. In synchronous mode, the data is transmitted at a fixed rate. In asynchronous mode, the data does not have to be transmitted at a fixed rate. Synchronous data is normally transmitted in the form of blocks , while asynchronous data is normally transmitted one byte at a time. Synchronous mode allows for a higher DTR (data transfer rate) than asynchronous mode does, if all other factors are held constant.

40. 1- WIRE INTERFACE - contents 1- wire interface- Introduction Advantages of 1- wire interface Disadvantages of 1- wire interface Applications of 1- wire interface.

41. 4.1- WIRE INTERFACE 1- Wire is a device communications bus system designed by Dallas Semiconductor Corp. 1- Wire is similar in concept to I²C, but with lower data rates and longer range. It is typically used to communicate with small inexpensive devices such as digital thermometers and weather instruments. One distinctive feature of the bus is the possibility of using only two wires: data and ground

42. There is always one master in overall charge, which may be a PC or a microcontroller. The master initiates activity on the bus, simplifying the avoidance of collisions on the bus. Protocols are built into the software to detect collisions. After a collision, the master retries the required communication. Many devices can share the same bus. The most significant byte is a standard (for the 1-wire bus) 8- bit CRC The master starts a transmission with a reset pulse, which pulls the wire to volts for at least 480 µs. This resets every slave device on the bus. After that, any slave device, if present, shows that it exists with a "presence" pulse: it holds the bus low for at least 60 µs after the master releases the bus. To send a "1", the bus master sends a very brief (1– 15 µs) low pulse. To send a "0", the master sends a 60 µs low pulse, When receiving data, the master start sends a 1–15-µs 0- volt pulse to slave each bit. If the transmitting does unit wants to send a "1", it to the nothing, and the bus goes transmitting pulled- up voltage. If the a "0", it pulls slave wants to send the data line to ground for 60 µs.

43. advantages of 1- wire interface Multiple slaves are accessed using only 2-wires in this interface type Due to use of less wires, the interface is cheaper. It is easy to implement the interface. The interface supports longer distance (about 300 meters) disadvantages of 1- wire interface It is implemented both in the hardware as well as software. The synchronization of data at the receiver has to be taken care in software which is a complex task. Though the interface supports longer distance, it is limited due to noise and cable capacitance. It supports slower speed of communication. 1- wire slave devices are manufactured by Dallas semiconductor only Applications of 1- wire interface. SDI- 12, a single data wire communications scheme/data loggers Touch memory Medical- pulse oximetry device Sensor/cable id authentication

44. EXTERNAL COMMUNICATION INTERFACE External communication interface refers to the different communication channels used by embedded system to communicate with the external world. The product level communication interface is responsible for data transfer between the E.S and other devices or modules. The external communication interface can be either a wired media or a wireless media and it can be a serial or a parallel interface Various external communication interfaces are RS232 /RS 422 AND RS485 USB (UNIVERSAL SERIAL BUS) INFRARED Bluetooth 5.Wi- Fi IEEE 1394 Fire wire Ethernet

45. 1.RS232 /RS 422 AND RS485 - contents 1.RS232 Introduction DB9 Connector Electrical Characteristics How RS232 Works? Advantages Disadvantages Applications RS232- cables 2.RS 422 Introduction Working RS422- 9 Pin connector (DB- 9) Advantages Disadvantages Applications RS422- cables 3.RS- 485 Introduction Working Differential transmission method  RS485 pin out DB9 connector Electrical Characteristics Advantages Disadvantages Comparison B/w rs232- 422- 485 Applications

46. 1.RS232 /RS 422 AND RS485 RS- 232 RS- 232 (Recommended Standard 232). It is basically a interface standards. It is commonly used in computer serial ports. The standard defines the electrical characteristics and timing of signals. RS- 232 was first introduced in 1962. For many years, an RS- 232- compatible port was a standard feature for serial communication. The standard continued to be revised and updated by the Electronic Industries Alliance and since 1988 by the Telecommunications Industry Association (TIA). The C revision of the standard was issued in August 1969. The current version of the standard is TIA232- F ,issued in 1997.

47. RS232 is a standard protocol used for serial communication, it is used for connecting computer and its peripheral devices to allow serial data exchange between them. It is used in serial communication up to 50 feet with the rate of 1.492kbps. As EIA defines, the RS232 is used for connecting Data Transmission Equipment (DTE) and Data Communication Equipment (DCE) Universal Asynchronous Data Receiver &Transmitter ( UART ) used in connection with RS232 for transferring data between printer/projector and computer. The microcontrollers are not able to handle such kind of voltage levels(5v), connectors are connected between RS232 signals. These connectors are known as the DB9 Connector as a serial port and they are of two type’s Male connector (DTE) & Female connector (DCE).

48. Rs232 - DB9 Connector

49. DCD, or Data Carrier Detect: This is an input for DTE devices and an output for DCE devices. This signal is used to show that there is a valid connection between the DTE and DCE devices TxD, or Transmit Data: This is an output for DTE devices and an input for DCE devices. This is the data channel from the DTE device to the DCE device. RxD, or Receive Data: This is an input for DTE devices and an output for DCE devices. This is the data channel from the DCE device to the DTE device. RTS, or Request To Send: This is an output for DTE devices and an input for DCE devices. This signal is typically used to gate flow from the DCE device to the DTE device. CTS, or Clear To Send: This is an input for DTE devices and an output for DCE devices. This signal typically is used to gate flow from the DTE device to the DCE device DSR, or Data Set Ready: This is an input for DTE devices and an output for DCE devices SG, or Signal Ground: This is a signal return for all signal lines DTR, or Data Terminal Ready : This is an output for DTE devices and an input for DCE devices. RI, or Ring Indicator: This is an input for DTE devices and an output for DCE devices. This signals the DTE device that there is an incoming call.

50. Electrical Characteristics Voltage Levels The logic ‘1’ in RS232 is described as being in the voltage range of - 15V to - 3V and logic ‘0’ is described as the voltage range of +3V to +15V i.e. low level voltage is logic ‘1’ and high level voltage is logic ‘0’. Slew Rate The other important electrical characteristic is the rate of change of signal levels i.e. the Slew Rate. The maximum slew rate in RS232 is limited to 30V/µs . Also, a maximum bit rate of 20 Kbps is also defined. These limitations of the standard help in reducing the cross – talk with adjacent signals. Line Impedance The line impedance i.e. impedance of the wire between the DTE and DCE devices is specified to be around 3Ω to 7Ω. Also, the original RS232 standard specifies the maximum length of the cable as 15 meters but the revised standards specify the maximum length in terms of capacitance per unit length.

51. How RS232 Works? RS232 works on the two- way communication that exchanges data to one another. There are two devices connected to each other, (DTE) Data Transmission Equipment& (DCE) Data Communication Equipment which has the pins like TXD, RXD, and RTS& CTS Now, from DTE source, the RTS generates the request to send the data. Then from the other side DCE, the CTS, clears the path for receiving the data. After clearing a path, it will give a signal to RTS of the DTE source to send the signal. Then the bits are transmitted from DTE to DCE. Now again from DCE source, the request can be generated by RTS and CTS of DTE sources clears the path for receiving the data and gives a signal to send the data. This is the whole process through which data transmission takes place. TXD RXD RTS CTS GND DCD DTR DSR - - - - - - - - TRANSMITTER RECEIVER REQUEST TO SEND CLEAR TO SEND GROUND DATA CARRIER DETECTIOR DATA TERMINAL READY DATA SET READY

52. Working Example: The signals set to logic 1, i.e., - 12V. The data transmission starts from next bit and to inform this, DTE sends start bit to DCE. The start bit is always ‘0’, i.e., +12 V & next 5 to 9 characters is data bits. If we use parity bit, then 8 bits data can be transmitted whereas if parity doesn’t use, then 9 bits are being transmitted. The stop bits are sent by the transmitter whose values are 1, 1.5 or 2 bits after the data transmission

53. Advantages Very widely used Low complexity Supports full duplex Disadvantages Only supports communication between two devices Only works over short distances Relatively susceptible to noise If there is an increase in baud rate and length of the cable, there is a chance of cross talk introduced by the capacitance between the cables Applications RS232 serial communication is used in old generation PCs for connecting the peripheral devices like mouse, printers, modem etc. Nowadays, RS232 is replaced by advanced USB. It is also used in PLC machines, CNC machines, and servo controllers because it is far cheaper. It is still used by some microcontroller boards, receipt printers, point of sale system (PoS), etc

54. RS232 null modem cables RS232 serial printer cable RS232 spy cable (monitor cable) DB9 RS232C Humidity and Temperature Sensor with RS232 signal level converter USB to RS- 232 Adapter

55. RS 422 RS- 422. Recommended Standard 422 RS 422 is a telecommunications standard for binary serial communications between devices. RS 422 is an updated version of the original serial protocol known as RS- 232. One device will be known as the data terminal equipment (DTE) and the other device is known as data communications equipment (DCE). Example is a serial link between the computer and printer, the computer is the DTE device and the printer is the DCE device. RS- 422 is a balanced four wire system. Two wire is for DTE transmit signal to DCE, and other two wire is for DCE transmit signal to DTE.

56. RS422 is able to provide data rates of up to 10 Mbps at distances up to 50 feet (15.24 meters). However using reduced data rates, RS422 is able to transmit data over distances of 4000 feet (~1220 meters): the maximum is 100 kbps at this distance. The key reason why RS422 is able to achieve these improvements results from the use of differential or balanced transmission techniques. The differential transmission method uses two signal lines to flow opposite- phase currents, and performs transmission using the potential difference between the signal lines. External noise affects the + side and - side signal lines equally, and differential transmission considers only the potential difference between the signal lines, so the effect of the noise is canceled, making it more difficult for operation errors to occur.

57. Lower voltage line levels are used for RS422: A space is represented by a line voltage level in the band between +2 and +6 volts while a mark is represented by a voltage in the range -2 to -6 volts. The range between +2 and - 2 volts provides a good noise margin for the system. The RS422 standard allows for line impedances down to 50 ohms while supporting the high data rates. Specification of RS- 422

58. RS422- 9 Pin connector (DB- 9)

59. Advantages of RS-422: High data rates Less subject to noise Longer cable lengths Disadvantages of RS- 422: Not as commonly used Unidirectional For most applications, only one transmitter is used Applications: These connectors were used both to support RS- 232 devices like modems , as well as AppleTalk networking, RS- 422 printers, and other peripherals. RS- 422 is a common transport mechanism for RS- 232 extenders. These consist of RS- 232 ports on either end of an RS- 422 connection

60. RS 422 DB44 pin serial card adapter RS 422 DB9 pin connector USB to RS 422 converter

61. RS-485 RS232 is an interface to connect one DTE, data terminal equipment to one DCE, data communication equipment at a maximum speed of 20 kbps with a maximum cable length of 50 feet. This was sufficient in the old days where almost all computer equipment were connected using modems, but soon after people started to look for interfaces capable of one or more of the following: Connect DTE's directly without the need of modems Connect several DTE's in a network structure Ability to communicate over longer distances Ability to communicate at faster communication rates RS485 is the most versatile communication standard in the standard series defined by the EIA, as it performs well on all four points. That is why RS485 is currently a widely used communication interface in data acquisition and control applications where multiple nodes communicate with each other.

62. RS485 pin out DB9 connector

63. Electrical specifications The RS- 485 standard specifies differential signaling on two lines. A logic 1 is a level greater than –200 mV, and a logic is a level greater than +200 mV The standard transmission medium is twisted- pair cable. Cable length defines the upper data rate. But because of the lower logic voltage levels and the differential connection, data rates can exceed 10 Mbits/s depending on cable length. Maximum cable length is commonly defined as 1200 meters or about 4000 feet. The typical maximum data rate at 4000 feet is 100 kbits/s RS485 SPECIFICATIONS ATTRIBUTE SPECIFICATION Cabling Multi- drop Number of devices 32 transmitters 32 receivers Communications modes half duplex Maximum distance 4000 feet @ 100 kbps Maximum data rate 10 Mbps @ 50 feet Signalling Balanced/Differential Driver output current capability 250 mA

64. Advantages of RS- 485 ➨ Due to use of differential signaling, maximum data transmission speed (100 Kbps) and distance upto 1200 meters (i.e. 4000 ft) are supported . ➨ Due to differential signaling RS485 interface is immune to noise. ➨ It supports single master and multiple slaves (i.e. multi-stations) due to balanced transmission line. ➨ It is considered to be lower signal level interface. ➨ Response time between reader and software is short when less than 32 controllers (or readers) are communicating on same data line. Disadvantages of RS- 485 ➨ In RS485 mode, only single mode can transmit data at a time. ➨ The RS485 interface requires special type of cables and ordinary cables can not be used. Moreover it is expensive. ➨ It requires 4 wires to communicate in multi- drop mode unlike RS232 which requires only 2 wires to communicate between master and slave in point to point mode. ➨ RS485 is not suitable to transfer large amount of data at 115.2 Kbps speed. This is due to occurrence of data loss at such high speed. Data transfer at 56.2 Kbps is stable but takes longer time. ➨ In RS485, backing up of system is difficult. This is because special switches and configurations are needed to build redundant host PC

65. Other types: RS- 366 interface RS- 423 (TIA/EIA-423- B) serial interface RS- 449 (EIA- 449) interface RS- 449 (EIA- 449) Secondary RS- 530 (EIA530) interface RS232 to RS422 cable RS232 to RS485 cable RS232 serial to USB converter

66. Introduction USB System Architecture Bus Topology USB host USB Devices USB System overview History of USB Key Features of USB USB Connector properties USB Connector types Difference between connector type A,B,C USB Evolution USB Protocol layer Token packets Data packets Handshake packets Start of frame packets Enumeration Steps Advantages of USB Disadvantages of USB 2.Universal Serial Bus (USB) - contents

67. Universal Serial Bus (USB) USB stands for Universal Serial Bus It Provides an expandable, fast, bi- directional, low cost, hot pluggable Plug and Play serial hardware interface It Allows users to connect a wide variety of peripherals to a computer and have them automatically configured and ready to use. It is Implemented to provide a replacement for legacy ports to make the addition of peripheral devices quick and easy for the end use

68. USB System Architecture A USB system is described by three definitional areas: USB interconnect USB host. USB devices 1. USB interconnect The USB interconnect is the manner in which USB devices are connected to and communicate with the host. This includes the following: Bus Topology: Connection model between USB devices and the host. Inter- layer Relationships: In terms of a capability stack, the USB tasks that are performed at each layer in the system. Data Flow Models : The manner in which data moves in the system over the USB between producers and consumers. USB Schedule : The USB provides a shared interconnect. Access to the interconnect is scheduled in order to support isochronous data transfers and to eliminate arbitration overhead.

69. Bus Topology: The USB connects USB devices with the USB host. The USB physical interconnect is a tiered star topology. A hub is at the center of each star. Each wire segment is a point-to- point connection between the host and a hub or function, or a hub connected to another hub or function. Figure illustrates the topology of the USB

70. 2.USB host. There is only one host in any USB system. The USB interface to the host computer system is referred to as the Host Controller. The Host Controller may be implemented in a combination of hardware, firmware, or software. A root hub is integrated within the host system to provide one or more attachment point The USB host interacts with USB devices through the Host Controller. The host is responsible for the following: Detecting the attachment and removal of USB devices Managing control flow between the host and USB devices Managing data flow between the host and USB devices Collecting status and activity statistics Providing power to attached USB devices The USB System Software on the host manages interactions between USB devices and host based device software. There are five areas of interactions between the USB System Software and device software: Device enumeration and configuration Isochronous data transfers Asynchronous data transfers Power management Device and bus management information

71. 3 USB Devices USB devices are one of the following: Hubs, which provide additional attachment points to the USB Functions, which provide capabilities to the system, such as an ISDN connection, a digital joystick, or speakers, cameras USB devices present a standard USB interface in terms of the following: Their comprehension of the USB protocol Their response to standard USB operations, such as configuration and reset Their standard capability descriptive information.

72. USB System overview

73. USB 0.7: Released in November 1994. USB 0.8: Released in December 1994. USB 0.9: Released in April 1995. USB 0.99: Released in August 1995. USB 1.0: Released in November 1995 There have been three versions released prior to 3.0 USB 1.0 in January 1996 – data rates of 1.5 Mbps up to 12 Mbps USB 1.1 in September 1998 – first widely used version of USB USB 2.0 in April 2000 Major feature revision was the addition of a high speed transfer rate of 480 Mbps. USB 3.0 On Nov 17,2008 It was Developed It is called as “SUPER SPEED” Technology Transfer Mode of Up to 4.8 Gbps USB 4.0? RELEASED 2019, THUNDERBOLT MODE History of USB

74. Key Features of USB Single connector type Replaces all different legacy connectors with one well defined standardized USB connector for all USB peripheral devices Hot swappable Devices can be safely plugged and unplugged as needed while the computer is running (no need to reboot) Plug and Play OS software automatically identifies, configures, and loads the appropriate driver when connection is made High performance USB offers data transfer speeds at up to 4.8 Gbps Expandability Up to 127 different peripheral devices may theoretically be connected to a single bus at one time Bus- supplied power USB distributes the power to all connected devices, eliminating the need for an external power source for low power devices (flash drives, memory cards, Bluetooth)

75. USB Connector properties Availability Consumer Products are always available. Usability Most connectors cannot be plugged in upside down Durability The standard connectors were designed to be robust Compatibility Two- way communication is also possible. In USB 3.0, full-duplex communications are done when using Super Speed (USB 3.0) transfer

76. Advantages of USB The universal serial bus is easy to use. It has robust connector system. It has low cost. It has variety of connector types and size available. It has true plug and play nature. It has Low power consumption. Daisy chain up to 127 USB components / peripherals at the same time to one PC. Fits almost all devices that have a USB port Disadvantages of USB ➨ Though the speed supported is higher in latest USB variants of USB V3 and V4, it is lower compare to gigabit Ethernet and Fire- wire interfaces. ➨ USB supports peer to peer communication. In this type of interface, communication takes place between host and peripheral and not between two hosts (or peripherals). Using OTG (On the Go) version of USB, this issue is avoided. In OTG device can function both as peripheral and host. ➨ USB standards support cables with length up to 5 meters. Beyond this, USB hubs are required to expand connectivity. ➨ Broadcasting is not possible in USB and communication of messages take place between host and peripheral only.

77. 3.INFRARED - contents Introduction IR transmission IR Reception Infrared Data Association(IrDA) IrDA protocol IrDA- phy layer Performance IrDA Advantages IrDA dis-advantages IrDA- Applications

78. 3.INFRARED IR, or infrared, communication is a common, inexpensive, and easy to use wireless communication technology. IR light is very similar to visible light, except that it has a slightly longer wavelength. The discovery of infrared radiation is ascribed to William Herschel , @1800 and Infra means “Below”. The light which is below the Red light “Infrared” This means IR is undetectable to the human eye - perfect for wireless communication. Infrared band of the electromagnet corresponds to 430THz to 300GHz and a wavelength of 980nm. The propagation of light waves in this band can be used for a communication system (for transmission and reception) of data. This communication can be between two portable devices or between a portable device and a fixed device.

79. IR transmission: The transmitter of an IR LED inside its circuit, which emits infrared light for every electric pulse given to it. This pulse is generated as a button on the remote is pressed, thus completing the circuit, providing bias to the LED. The LED on being biased emits light of the wavelength of 940nm as a series of pulses, corresponding to the button pressed. However, since along with the IR LED many other sources of infrared light such as us human beings, light bulbs, sun, etc, the transmitted information can be interfered. A solution to this problem is by modulation. The transmitted signal is modulated using a carrier frequency of 38 KHz (or any other frequency between 36 to 46 KHz). The IR LED is made to oscillate at this frequency for the time duration of the pulse. The information or the light signals are pulse width modulated and are contained in the 38 KHz frequency

80. IR Reception The receiver consists of a photo- detector which develops an output electrical signal as light is incident on it. The output of the detector is filtered using a narrow band filter that discards all the frequencies below or above the carrier frequency (38 KHz in this case). The filtered output is then given to the suitable device like a Microcontroller or a Microprocessor which controls devices like a PC or a Robot. The output from the filters can also be connected to the Oscilloscope to read the pulses.

81. Infrared Data Association(IrDA) I nfra r ed D ata A ssociation, a group of device manufacturers that developed a standard for transmitting data via infrared light waves. Increasingly, computers and other devices (such as printers ) come with IrDA ports . This enables you to transfer data from one device to another without any cables. For example, if both your laptop computer and printer have IrDA ports, you can simply put your computer in front of the printer and output a document , without needing to connect the two with a cable. IrDA ports support roughly the same transmission rates as traditional parallel ports . The only restrictions on their use is that the two devices must be within a few feet of each other and there must be a clear line of sight between them.

82. IrDA protocol

83. Infrared physical layer (IrPHY) This specification is intended to facilitate point- to- point communication between electronic devices. It specifies the optical media interfaces for Serial Infrared (SIR) data transmission and is part of the first layer of the OSI model. Infrared link access protocol (IrLAP) This specification is part of the second layer of IrDA specifications. It lies on top of the IrPHY layer and below the IrLMP layer. It represents the data link layer. Infrared link management protocol (IrLMP) It is the third layer of IrDA specifications. It defines link management multiplexer and link management information access service. Transport protocol (TinyTP) This optional protocol specified in the fourth layer lies on top of the IrLMP layer. Infrared communication protocol (IrCOMM) The IrCOMM protocol specified in the fifth layer lets the infrared device act like either a serial or parallel port. Infrared Financial Messaging (IrFM) This protocol specified in the sixth layer is a wireless payment standard developed by the Infrared Data Association.

84. Low power requirements : Therefore ideal for laptops, telephones, personal digital assistants Low circuitry costs : $2- $5 for the entire coding/decoding circuitry Simple circuitry : No special or proprietary hardware is required, can be incorporated into the integrated circuit of a product Higher security: Directionality of the beam helps ensure that data isn't leaked or spilled to nearby devices as it's transmitted Portable Few international regulatory constraints : IrDA (Infrared Data Association) functional devices will ideally be usable by international travelers. High noise immunity: Not as likely to have interference from signals from other devices ADVANTAGES

85. Line of sight: Transmitters and receivers must be almost directly aligned (i.e. able to see each other) to communicate Blocked by common materials: people, walls, plants, etc. can block transmission Short range : performance drops off with longer distances Light, weather sensitive: direct sunlight, rain, fog, dust, pollution can affect transmission Speed: data rate transmission is lower than typical wired transmission DISADVANTAGES

86. Medicine: - Doctors use infrared lamps to treat skin diseases and relieve the pain of sore muscles. Military : Infrared imaging is used extensively in military for target acquisition, surveillance, wireless communication, night vision, homing and tracking. Science: Infrared have allowed buildings to keep cool even in the summer. Gold transparent films in the windows of large office buildings reflect infrared and help to keep temperatures cool. Consumer Goods: Photographers use film that is sensitive to infrared rays to take pictures in places where there is no visible light. - TVs, VCRs and CD players also use infrared. Industry: Infrared is used extensively in specially-designed ovens for drying painted and enameled surfaces, leather, metals, papers and textiles. Applications

87. Spectroscopy Infrared vibrational spectroscopy is a technique that can be used to identify molecules by analysis of their constituent bonds. The vibrational frequencies of most molecules correspond to the frequencies of infrared light. Typically, the technique is used to study organic compounds using light radiation. Thin film metrology In the semiconductor industry, infrared light can be used to characterize materials such as thin films and periodic trench structures. Meteorology Weather satellites equipped with scanning radiometers produce thermal or infrared images, which can then enable a trained analyst to determine cloud heights and types, to calculate land and surface water temperatures, and to locate ocean surface features. Climatology In the field of climatology, atmospheric infrared radiation is monitored to detect trends in the energy exchange between the earth and the atmosphere. These trends provide information on long-term changes in Earth's climate. It is one of the primary parameters studied in research into global warming, together with solar radiation. Art conservation and analysis Infrared reflectography can be applied to paintings to reveal underlying layers in a non- destructive manner, in particular the artist's underdrawing or outline drawn as a guide

88. USB to IrDA receptor

89. 4.Bluetooth - contents Bluetooth Introduction The Name History How Bluetooth wireless technology works BWT network topologies pico- net scatter- net Bluetooth Connection Process Bluetooth Protocol core protocols cable replacement protocols telephony control protocols adopted protocols Bluetooth – chip Comparison between Bluetooth versions Advantages of Bluetooth Dis-Advantages of Bluetooth Applications of Bluetooth

90. Bluetooth is a short- range and low power wireless technology originally developed for exchanging data over short distances from fixed and mobile devices, creating personal area networks (PANs). Short- range radio frequency technology that operates at 2.4 GHz on an unlicensed Industrial Scientific Medical (ISM) band. Effective range of Bluetooth devices is 10 meters. Bluetooth can connect up to “ eight devices” simultaneously and each device offers a unique 48 bit address from the IEEE 802 standard with the connections being made point to point or multipoint. It was originally conceived as a wireless alternative to data cables 4.Bluetooth - Introduction

91. Bluetooth: The Name The word "Bluetooth" is taken from the 10th century Danish Viking King Harald Gormsson, he had been influential in uniting Scandinavian tribes into a single kingdom. Likes to eat blueberries King of Denmark and Norway Aka. Harald Blåtand (Harald Bluetooth)) Bluetooth was named so because Bluetooth technology was developed in Scandinavia. Bluetooth technology is able to unite differing industries such as the cell phone, computing, and automotive markets

92. 1994 : Ericsson study complete / vision 1995 : Engineering work begins 1997 : Intel agrees to collaborate 1998 : Bluetooth SIG formed: Ericsson, Intel, IBM, Nokia & Toshiba 1999 : Bluetooth Specification 1.0A SIG promoter group expanded: 3Com, Lucent, Microsoft & Motorola 2000 : Bluetooth Specification 1.0B, 2000+ adopters 2001 : First retail products released, Specification 1.1 2003 : Bluetooth Specification 1.2 2004: Bluetooth 2.0 + EDR 2007: Bluetooth 2.1 2009: Bluetooth 3.0 + HS 2010: Bluetooth 4.0 2013: Bluetooth 4.1 2014: Bluetooth 4.2 2016: Bluetooth 5 Bluetooth History

93. How Bluetooth wireless technology works BWT-enabled devices operate in the unrestricted 2.4- gigahertz (GHz) Industrial, Science, Medical (ISM) band. The ISM band ranges between 2.400 GHz and 2.483 GHz BWT-enabled devices use a technique called frequency hopping to minimize eavesdropping and interference from other networks that use the ISM band. With frequency hopping, the data is divided into small pieces called packets. The transmitter and receiver exchange a data packet at one frequency, and then they hop to another frequency to exchange another packet. They repeat this process until all the data is transmitted. BWT devices randomly hop between frequencies up to 1600 times per second— much faster than other types of devices that use the ISM band. This gives BWT networks a high immunity to interference from other 2.4- GHz devices. There are three classes of BWT radio devices, each with a different maximum range: Class 1 (100 meters); Class 2 (50 meters); and Class 3 (10 meters)

94. BWT network topologies BWT- enabled devices form network topologies called Pico- nets and scatter- nets. A pico- net consists of up to eight BWT- enabled devices When a pico- net is established, one device sets the frequency- hopping pattern and the other devices synchronize their signals to the same pattern. The device that sets the frequency- hopping pattern is called the primary device and the other devices are called secondary devices. Each pico- net has a different frequency-hopping pattern to differentiate its signals from the signals of other pico-nets

95. A scatter- net is formed when two or more pico- nets are linked by a common BWT- enabled device. When a device is present in multiple pico- nets, it synchronizes to the master of each pico- net with which it is currently communicating and sets the hopping pattern of the pico- net in which it is the master

96. Bluetooth Connection Process Creating a Bluetooth connection between two devices is a multi- step process involving three progressive states: Inquiry – If two Bluetooth devices know absolutely nothing about each other, one must run an inquiry to try to discover the other. One device sends out the inquiry request, and any device listening for such a request will respond with its address, and possibly its name and other information. Paging (Connecting ) – Paging is the process of forming a connection between two Bluetooth devices. Before this connection can be initiated, each device needs to know the address of the other (found in the inquiry process) Connection – After a device has completed the paging process, it enters the connection state. While connected, a device can either be actively participating or it can be put into a low power sleep mode Active Mode – This is the regular connected mode, where the device is actively transmitting or receiving data. Sniff Mode – This is a power- saving mode, where the device is less active. It’ll sleep and only listen for transmissions at a set interval (e.g. every 100ms). Hold Mode – Hold mode is a temporary, power- saving mode where a device sleeps for a defined period and then returns back to active mode when that interval has passed. The master can command a slave device to hold. Park Mode – Park is the deepest of sleep modes. A master can command a slave to “park”, and that slave will become inactive until the master tells it to wake back up

97. Bluetooth Protocol

98. Bluetooth is defined as a layer protocol architecture consisting of core protocols Radio (RF) layer, Baseband Link layer, Link Manager protocol layer Logical Link Control and Adaption protocol layer, Service Discovery Protocol cable replacement protocols RF comm layer telephony control protocols telephony service adopted protocols Point- to- Point Protocol, TCP/IP/UDP, Object Exchange Protocol, Wireless Application Environment/Wireless Application Protocol Bluetooth Protocol architecture

99. Bluetooth protocol Architecture - core protocols Radio (RF) layer: It performs modulation/demodulation of the data into RF signals. It defines the physical characteristics of Bluetooth transceiver. It specifies the usage frequency hopping. Baseband Link layer: It performs the connection establishment within a piconet. Addressing scheme, packet frame format , timing and power control algorithms required for establishing connection between Bluetooth devices within piconet defined in this part of protocol specification. Link Manager protocol : It is responsible to establish link between Bluetooth devices and to maintain the link between them. This protocol also includes authentication and encryption specifications. Negotiation of packet sizes between devices can be taken care by this. Logical link control and adaptation protocol : This L2CAP protocol adapts upper layer frame to baseband layer frame format and vice versa. L2CAP take care of both connection oriented and connectionless services. Service discovery protocol : Service related queries including device information can be taken care at this protocol so that connection can be established between Bluetooth devices.

100. Bluetooth protocol Architecture - cable replacement protocols Radio Frequency Communications (RFCOMM) RFCOMM is a cable replacement protocol used for generating a virtual serial data stream. Serial ports are popular to provide serial communication between devices. Bluetooth uses RFCOMM as cable replacement protocol. RFCOMM functions as virtual serial port and does transport of binary digital data bits. It basically emulates RS232 specifications over Bluetooth physical layer.

101. Bluetooth protocol Architecture - telephony control protocols The Telephony Control Protocol – Binary TCS BIN is the bit- oriented protocol that defines the call control signaling for the establishment of voice and data calls between Bluetooth devices. Additionally, "TCS BIN defines mobility management procedures for handling groups of Bluetooth TCS devices." TCS- BIN is only used by the cordless telephony profile, which failed to attract implementers.

102. Bluetooth protocol Architecture- adopted protocols These protocols are already defined by other standard bodies which are incorporate without any change in the Bluetooth protocol stack architecture. point to point protocol(PPP) Internet standard protocol for transporting IP datagrams over a point- to- point link. TCP/UDP and IP Foundation Protocols for TCP/IP protocol suite object exchange protocol OBEX is a object exchange protocol developed by IrDA and it is similar to HTTP. It is a session level protocol. Wireless Application Environment/Wireless Application Protocol (WAE/WAP) WAE specifies an application framework for wireless devices and WAP is an open standard to provide mobile users access to telephony and information services The Audio/Video Control Transport Protocol AVCTP is used by the remote control profile to transfer AV/C commands over an L2CAP channel. The music control buttons on a stereo headset use this protocol to control the music player.

103. Bluetooth – chip Bluetooth devices are fabricated on RF CMOS integrated circuit (RF circuit) chips. Hardware The hardware that makes up the Bluetooth device is made up of, logically, two parts; A radio device , responsible for modulating and transmitting the signal; and The digital controller is likely a CPU, one of whose functions is to run a Link Controller; and interfaces with the host device. The CPU of the device is responsible for attending the instructions related to Bluetooth of the host device, in order to simplify its operation. Software Seeking to extend the compatibility of Bluetooth devices, the devices that adhere to the standard use an interface called HCI (Host Controller Interface) between the host device (e.g. laptop, phone) and the Bluetooth device (e.g. Bluetooth wireless headset). High- level protocols such as the SDP, RFCOMM (Protocol used to emulate serial port connections) and TCS (Telephony control protocol) interact with the baseband controller through the L2CAP Protocol (Logical Link Control and Adaptation Protocol).

104. Bluetooth 1.0 1998 – 2003 “Base Rate” 1Mbps data rate Gaussian Frequency Shift Keying V1.0 ‐ Draft V1.0A ‐ published on 1999 V1.0B Enhanced Interoperability V1.1 ‐ IEEE 802.15.1 V1.2 Enhanced the compatibility Bluetooth 2.0 + EDR 2004– 2007. “Enhanced Data Rate” Higher ordered modulation for data payload 2Mbps or 3Mbps physical data rate DQPSK/DPSK V2.0 V2.1 Bluetooth 3.0 + HS 2009 “HS Mode” AMP- Alternative MAC/PHY Implement high data rate by using 802.11 protocols. 24 Mbps of data transfer Facing the Challenge from Wi‐Fi V3.0 Bluetooth 4.0 2010 – 2014 “Low Energy” Facing the IoT application Changed the protocol greatly, almost a new technology Gaussian Frequency Shift Keying LE Link Layer Topology 1Mbps data transfer V4.0 V4.1 V4.2 Bluetooth 5.0 2016 on- words “Low Energy” IoT applications 2Mbps, 1Mbps, 500kbps, 125kbps Gaussian Frequency Shift Keying Mesh- based model hierarchy V5.0 V5.1 V5.2

105. Advantages of Bluetooth ➨ It creates ad- hoc connection immediately without any wires. Connection establishment is very quick. User only need to pair the Bluetooth PAN connection between two devices. ➨ It has low power consumption. ➨ It can pass through walls. ➨ It has range better than Infrared communication. ➨ It has been managed by Bluetooth SIG and hence products from large companies are available and there is no issue of interoperability among different Bluetooth vendor products. ➨ It is used for voice and data transfer. ➨ It uses FHSS and hence data communication is more secure. ➨ The technology is adopted in many products such as head set, in car system, printer, web cam, GPS system, keyboard and mouse. ➨ Due to availability of Bluetooth headphones, calls can be taken on phone even while driving and doing some other activity simultaneously. This hands free operation relieves great strain. ➨ Bluetooth devices are available at very cheap cost. ➨ It has less interference compare to other wireless technologies due to use of FHSS technique

106. Disadvantages of Bluetooth ➨ One of the big disadvantages of Bluetooth is security. This is due to the fact that it operates on Radio frequency and hence can penetrate through walls. It is advisable not to use it for critical business or personal data transfer. ➨ As Home RF technology operates on same frequency, It has interference from it. ➨ The bandwidth is lower compare to Wi- Fi. ➨ Battery usage is more compare to the condition when Bluetooth is powered OFF. The new technology known as BLE or Bluetooth low energy or Bluetooth smart is developed to enhance the battery life further ➨ Limited Operational Range- Enabled devices can only establish and maintain wireless communication as long as they are within the range limit

107. 4.Wi- Fi – contents Computer Networks - Introduction The OSI Reference model Wi- Fi (wireless fidelity) Introduction Naming and Logo History Elements of a WI- FI Network How a Wi- Fi Network Works IEEE 802.11 Protocol Architecture IEEE 802.11 Physical Layers IEEE 802.11 Data Link Layer Wi- Fi Technology Standards Advantages of Wi- Fi Dis- advantages of Wi- Fi Applications of Wi- Fi

108. 4.WiFi (wireless fidelity) Computer Networks A computer network is two or more computers connected together using a telecommunication system for the purpose of communicating and sharing resources Goal : Universal Communication (any to any) Type of Networks PAN : a personal area network is a computer network (CN) used for communication among computer devices (including telephones and personal digital assistants) close to one person Technologies : USB and Fire- wire (wired), IrDA and Bluetooth (wireless) LAN : a local area network is a CN covering a small geographic area, like a home, office, or group of buildings Technologies : Ethernet (wired) or Wi- Fi (wireless) MAN : Metropolitan Area Networks are large CNs usually spanning a city Technologies : Ethernet (wired) or WiMAX (wireless) WAN: Wide Area Network is a CN that covers a broad area, e.g., cross metropolitan, regional, or national boundaries Examples : Internet Wireless Technologies : HSDPA, EDGE, GPRS, GSM.

109. The OSI Reference model

110. Wireless Technology is an alternative to Wired Technology, which is commonly used, for connecting devices in wireless mode. Wi- Fi uses a radio technology, which can transmit data over short distances using high frequencies Wi- Fi (Wireless Fidelity) is a generic term that refers to the IEEE 802.11 communications standard for Wireless Local Area Networks (WLANs). The 802.11 standard provides several distinct radio frequency ranges for use in Wi- Fi communications: 900 MHz, 2.4 GHz, 3.6 GHz, 4.9 GHz, 5 GHz, 5.9 GHz and 60 GHz bands . Wi- Fi Network connect computers to each other, to the internet and to the wired network. Wi- Fi works on physical and data link layer. The purpose of Wi- Fi is to hide complexity by enabling wireless access to applications and data, media and streams. The main aims of Wi- Fi are the following: make access to information easier ensure compatibility and co- existence of devices eliminate cabling and wiring eliminate switches, adapters, plugs, pins and connectors WiFi (wireless fidelity)

111. ” In 1999 Wi- Fi alliance was formed and it took help of a brand building company to come up with a catchy name. It just came up with the play of words rhyming similar to Hi- Fi (a term for high- quality audio technology). Later to that the alliance used the punch line " The standard for Wireless Fidelity " and this lead to the misconception that Wi-Fi is Wireless Fidelity. Phil Belanger who is the founding member of the Wi- Fi Alliance states that term Wi- Fi was never supposed to mean anything at all The exact technical name of Wi- Fi is “ IEEE 802.11b Direct Sequence The “yin- yang” logo indicates the certification of a product for interoperability. WiFi (wireless fidelity) – Naming and Logo

112. 1971: ALOHA net connected the Hawaiian Islands with a UHF wireless packet network. ALOHA net and the ALOHA protocol were early forerunners to Ethernet, and later the IEEE 802.11 protocols, respectively. 1974 : 1985 1991 : Vic Hayes is often regarded as the “father of Wi- Fi.” He started such work in 1974 when he joined NCR Corp. The U.S. Federal Communications Commission released the ISM band for unlicensed use. NCR Corporation with AT&T Corporation invented the precursor to 802.11, intended for use in cashier systems. The first wireless products were under the name WaveLAN 1992 and 1996 :CSIRO obtained patents for a method later used in Wi-Fi to "unsmear" the signal. 1997 :The first version of the 802.11 protocol was released , and provided up to 2 Mbit/s link speeds. 1999 : This was updated with 802.11b to permit 11 Mbit/s link speeds, and this proved to be popular as WiFi 1 1999: Wi- Fi Alliance formed as a trade association to hold the Wi- Fi trademark under which most products are sold. IEEE 802.11a– WiFi 2 2003 : IEEE 802.11g – WiFi 3 2007: IEEE 802.11REVma created a single document that merged 8 amendments ( 802.11a , b , d , e , g , h , i , j ) with the base standard. 2009: IEEE 802.11n – WiFi 4 2012: IEEE802.11REVmB created a single document that merged ten amendments ( 802.11k , r , y , n , w , p , z , v , u , s ) with the 2007 base standard 2013:IEEE 802.11ac &IEEE 802.11ad – WiFi 5 2014:IEEE 802.11af , also referred to as "White- Fi" and "Super Wi- Fi“ 2016:IEEE 802.11 REVmc , is a revision based on IEEE 802.11- 2012, incorporating 5 amendments (11ae, 11aa, 11ad, 11ac, 11af) 2017:IEEE 802.11af 2019:IEEE 802.11ax- WiFi- 6 2023: IEEE 802.11be –WiFi 7 WiFi - History

113. Elements of a WI- FI Network Access Point (AP) - The AP is a wireless LAN transceiver or “base station” that can connect one or many wireless devices simultaneously to the Internet. A wireless router is a device that enables wireless network packet forwarding and routing, and serves as an access point in a local area network. It works much like a wired router but replaces wires with wireless radio signals to communicate within and to external network environments. It can function as a switch and as an Internet router and access point. Wi- Fi cards - They accept the wireless signal and relay information. They can be internal and external.(e.g PCMCIA Card for Laptop and PCI Card for Desktop PC) Antennae Most antennae for wireless LANs are omnidirectional and have low gain. Nearly all access points, routers, and repeaters come standard with omnidirectional antennae. Omnidirectional antennae satisfy most coverage requirements; however, consider the use of optional directive antennae to cover a long, narrow area. In some cases, the antenna is integrated within a radio card or access point and there is no choice to make. If a need exists to use a directive antenna (higher gain), ensure that the radio card or access point has an external antenna connector

114. How a Wi- Fi Network Works

115. IEEE 802.11 Physical Layers IEEE 802.11 Frequency Hopping Spread Spectrum (FHSS) Frequency hopping works by modulating a data signal with a carrier signal that hops from frequency to frequency as a function of time over a wide band of frequencies. With 802.11 FHSS, the carrier frequency hops over the 2.4GHz frequency band between 2.4GHz and 2.483GHz. Advantage: Capability to operate up to 10 collocated access points without significant interference IEEE 802.11 Direct Sequence Spread Spectrum (DSSS) IEEE 802.11 DSSS combines a data signal at the sending station with a higher data rate bit sequence, which many refer to as a chipping code. The IEEE 802.11 Working Group has set its minimum processing gain requirements at 11, which means that the chipping code multiplies the data signal by 11. Direct sequence spread spectrum sends a specific string of bits for each data bit sent. A chipping code is assigned to represent logic 1 and data bits. As the data stream is transmitted, the corresponding code is actually sent. For example, the transmission of a data bit equal to 1 would result in the sequence 00010011100 being sent. Advantage: Highest potential data rates from individual physical layers, which is why DSSS was chosen for a higher-rate 802.11 physical layer (802.11b)

116. IEEE 802.11 Physical Layers IEEE 802.11b High- Rate Direct Sequence Spread Spectrum (HR- DSSS) IEEE 802.11 HR- DSSS The IEEE 802.11b version of the standard is a data rate extension of the initial 802.11 DSSS, providing operation in the 2.4GHz band with additional data rates of 5.5 and 11Mbps. All primary wireless LAN vendors offer 802.11b radio cards and access points. In addition, the IEEE 802.11 working group is considering an enhancement of the standard to double this data rate to 22Mbps. IEEE 802.11a Orthogonal Frequency Division Multiplexing (OFDM) The IEEE 802.11a standard specifies a modulation that divides a high-speed serial information signal into multiple lower- speed "sub- signals" that the system transmits simultaneously at different frequencies in parallel over a 20MHz channel located in the 5GHz frequency band. This parallel form of transmission over multiple subcarriers enables OFDM- based wireless LANs to operate at higher aggregate data rates. 802.11a has a wide variety of high-speed data rates available: 6, 9, 12, 18, 24, 36, 48, and 54Mbps. The 6, 12, and 24Mbps rates are mandatory for all products.

117. This Data Link Layer is divided into two sub-layers: Logical Link Control (LLC). This sub- layer is responsible for the data transmission between computers or devices on a network. Media Access Control (MAC). On a network, the network interface card (NIC) has an unique hardware address which identifies a computer or device. The physical address is utilized for the MAC sub- layer addressing. The function of the Logical Link Control (LLC) is to manage and ensure the integrity of data transmissions. The LLC provides Data Link Layer links to services for the Network Layer protocols. This is accomplished by the LLC Service Access Points (SAPs) for the services residing on network computers. Also, there is a LLC Control field for delivery requests or services. The Logical Link Control (LLC) has several service types: Service type 1, is a connectionless service with no establishment of a connection, and an unacknowledged delivery. Service type 2, is a connection logical service with an acknowledgement of delivery. Service type 3, is a connectionless service with an acknowledgement of deliver IEEE 802.11 Data Link Layer

118. Media Access Control (MAC). MAC layer provides functionality for several tasks like control medium access, can also offer support for roaming, authentication, and power conservation. The basic services provided by MAC are the mandatory asynchronous data service and an optional time- bounded service. IEEE 802.11 defines two MAC sub-layers :- Distributed Coordination Function (DCF) – DCF uses CSMA/CD as access method as wireless LAN can’t implement CSMA/CD. It only offers asynchronous service. Point Coordination Function (PCF) – PCP is implemented on top of DCF and mostly used for time- service transmission. It uses a centralized, contention- free polling access method. It offers both asynchronous and time- bounded service

119. Wi- Fi Technology Standards The IEEE develops and maintains a large number of standards associated with the electrical and electronics industries - not only do these include the Wi- Fi 802.11 series of standards, but also many others including those for Ethernet, IEEE 802.3. All the Wi-Fi standards come under the IEEE 802 umbrella for local area and metropolitan area networking, LAN / MAN. The Wi- Fi standards come under the IEEE 802.11 series. The most common set of wireless standards are IEEE 802.11b IEEE 802.11a IEEE 802.11g IEEE 802.11n IEEE 802.11ac IEEE 802.11ax IEEE 802.11be (WiFi 1) (WiFi 2) (WiFi 3) (WiFi 4) (WiFi 5) (WiFi 6) (WiFi 7)

120. Appears in late 1999 Operates at 2.44Ghz radio spectrum 11Mbps (theoretical speed)- within 30 meter Range 4- 6 Mbps Actual Speed 100- 150 feet range Limits the number of access points in range of each other to three Most Popular , Least Expensive Interference from Mobile Phones and Bluetooth device which can reduce transmission speed Uses direct- sequence spread- spectrum technology 1.IEEE 802.11b Standard Introduce in 2001 Operates at 5GHz Less popular and Less interfered 54 Mbps (theoretical Speed) 15- 20 Mbps (Actual Speed) 50- 75 feet range More Expensive Highly Obstructed Not Compatible with 802.11b Uses frequency division multiplexing 2.IEEE 802.11a Standard

121. 3. IEEE 802.11g Standard Introduce in 2003 Combine features of both a and b 100- 150 feet range 54 Mbps (theoretical speed) 20- 25 Mbps (actual Speed) 2.4 GHz radio frequency Compatible with b Uses frequency division multiplexing 4. IEEE 802.11n Standard 802.11n also known as Wireless N 802.11n Ratified in 2009 802.11n builds upon previous 802.11 standards by adding multiple- input multiple- output (MIMO). Operates on Both 2.4Ghz and 5Ghz Provide Bandwidth up to 300Mbps Backward- compatible with 802.11b/g gear Increased Speed and range

122. 5.IEEE 802.11ac Standard Builds on 802.11n ,Published in 2013 The addition of Multi- user MIMO (MU- MIMO) Utilizes dual band wireless technology Support Connection both 2.4 GHz and 5GHz Backward compatibility to 802.11b/g/n Bandwidth rated up to 1300 Mbps on the 5 GHz bandwidth rated up to 450 Mbps on the 2.4 GHz Builds on 802.11n ,Published in 2019 IEEE 802.11ax, marketed as Wi- Fi 6 by Wi- Fi Alliance, is a current generation Wi- Fi specification standard 802.11ax addresses frequency bands between 1 GHz and 6 GHz Supports orthogonal frequency- division multiple access (OFDMA), higher order 1024- QAM. The addition of MIMO and Multi- user MIMO (MU- MIMO) Frequency bands - 2.4 GHz and 5GHz 6 GHz for Wi- Fi 6E as spectrum is allocated globally Bandwidth rated up to 600.4 Mbps ( 80 MHz channel & 1 SS *) 9607.8 Mbps (160 MHz channel & 8SS *) 6.IEEE 802.11ax Standard

123. 7.IEEE 802.11be Standard WiFi 7: the next generation of WiFi technology IEEE 802.11be Extremely High Throughput (EHT) is the potential next amendment of the 802.11 IEEE standard Mainly focusing on WLAN indoor and outdoor operation with stationary and pedestrian speeds in the 2.4, 5 and 6 GHz frequency. the Wi- Fi Alliance will most likely certify it as Wi- Fi 7 Features: 320 MHz bandwidth and more efficient utilization of non- contiguous spectrum, Multi-band/multi- channel aggregation and operation, 16 spatial streams and Multiple Input Multiple Output (MIMO) protocols enhancements, Multi- Access Point (AP) Coordination (e.g. coordinated and joint transmission), Enhanced link adaptation and retransmission protocol (e.g. Hybrid Automatic Repeat Request (HARQ)), If needed, adaptation to regulatory rules specific to 6 GHz spectrum. Integrating Time- Sensitive Networking (TSN) extensions for low- latency real- time traffic (IEEE 802.11aa)

124. Standard Year Frequency band Bandwidth Transmission Scheme Modulation scheme MIMO Max Data rate Maximum Range IEEE 802.11b 1999 2.4GHz 20MHz DSSS QPSK No 11Mbps 450ft. IEEE 802.11a 2001 5GHz 20MHz OFDM QPSK No 54Mbps 400ft. IEEE 802.11g 2003 2.4GHz 20MHz DSSS,OFDM 64QAM No 54Mbps 450ft. IEEE 802.11n 2009 2.4GHz 5GHz 20MHz 40MHz OFDM 64QAM Yes 600Mbps 825ft. IEEE 802.11ac 2013 2.4GHz 5GHz 20MHz 40MHz 80MHz 160MHz OFDM 64QAM Yes 1300Mbps 1000ft. IEEE 802.11ax 2019 2.4GHz 6GHz 20MHz 40MHz 80MHz 160MHz OFDM 1024QAM Yes 10Gbps 1000ft. IEEE 802.11be 2022 2.4GHz 5GHz 6GHz 20MHz 40MHz 80MHz 160MHz --- - --- - Yes --- - -- -

125. Advantages of WiFi ➨ It is easy to add or move wifi clients or wifi stations to the wifi network created by AP (Access Point). ➨ Installation is very quick and easy. It does not require technical knowledge of wifi or wlan system and its protocols. ➨ Access to the wifi network can be availed from anywhere within the wifi AP (Access point) coverage range. ➨ WiFi enabled USB dongles are available at very affordable rates from TP- Link, D-Link, Tenda etc. ➨ Latest wifi standard versions such as 11n and 11ac deliver fast data connection rates e.g. 300 Mbps and higher. ➨ As it is easy to integrate wifi functionality in the mobile computing devices; it is now being used by millions of people using various devices such as PCs, laptops, PDAs, Printers, Cameras, Games, MP3 players, smartphones etc

126. ➨ Data transfer rate decreases (to individual computer) when number of clients or computers connected with wifi network increases. ➨ Full security is difficult to achieve due to wifi connection being wireless in nature. It requires proper security authentication protocols and configurations. ➨ Wifi devices operate in full functionality and without any interruptions when they are within the range of AP and receiving good signal strength. WiFi access is limited to about 30 to 100 meters (i.e. 100 to 300 feet). ➨ In case wifi connection does not work, minimal troubleshooting are needed. This requires one to understand basics of wifi device from user manual provided by the manufacturer. ➨ Before using wifi device, one need to install software from the CD provided by the manufacturer in the desktop or laptop. Disadvantages of WiFi

127. Applications Internet Access Voice over Wireless Inventory Control Health Care Education Real Estate Public Networks Vending Field Sales

128. 6.Ethernet- contents Ethernet Introduction History IEEE Ethernet standards Types of Ethernet Networks Ethernet- Protocol stack How does Ethernet work? IEEE 802.3 Physical layer Ethernet MAC layer Data Frame format The CSMA/CD protocol Wireless Ethernet Advantages and disadvantages

129. Ethernet – Introduction Ethernet, pronounced "E- thernet" (with a long "e"), is the standard way to connect computers on a network over a wired connection. It provides a simple interface and for connecting multiple devices, such computers, routers, and switches. With a single router and a few Ethernet cables, you can create a LAN which allows all connected devices to communicate with each other Ethernet is a family of computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1983 as IEEE 802.3 Over time, Ethernet has largely replaced competing wired LAN technologies such as Token Ring, FDDI and ARCNET. The Ethernet technology mainly works with the fiber optic cables that connect devices within a distance of 10 km

130. Ethernet- History 1968 : Norman Abramson pioneered the precepts of Ethernet by developing this packet radio networking system that ran at 4800 bps and 9600 bps. 1973 : Robert Metcalfe and David Boggs at Xerox Corporation in Palo Alto, CA applied the ALHOA network principles and created the world’s first Local Area Network (LAN). Initially named ALTO ALOHA, the name was later changed to Ethernet. This first version of Ethernet ran at speeds up to 2.94 Mbps. 1980 : The first commercial release of Ethernet was by DEC, Intel, and Xerox (DIX) in 1980 as Ethernet, Version 1. It was commonly referred to as Ethernet DIX80. 1982 : The second revision release, Ethernet, Version 2, was released. It was commonly referred to as Ethernet DIX82. Ethernet, Version 2 is the standard of Ethernet technology that is in use today. In 1980 , the IEEE formed Project 802 to provide a framework for the standardization of LAN technology. 1983 : Novell released Novell Netware ’86 , which used a proprietary frame format based on a preliminary specification of the IEEE 802.3 standard. This is the same Novell software that is used today to manage printers and servers. In 1983 , the IEEE approved the IEEE 802.3 standard, which included IEEE 802.2 Logical Link Control (LLC). This made Novell Netware’s proprietary format incompatible with the latest technology. In the late 1980 s, SynOptics Communications developed a mechanism for transmitting 10 Mbps Ethernet signals over twisted- pair cables. The Ethernet-over-twisted- pair specification (10 BASE- T) was approved by the IEEE in 1990 as the IEEE 802.3i standard. It quickly became the preferred Ethernet media type.

131. IEEE Ethernet standards Ethernet is defined in a number of IEEE 802.3 standards. These standards define the physical and data- link layer specifications for Ethernet. The most important 802.3 standards are: 10Base- T (IEEE 802.3) – 10 Mbps with category 3 unshielded twisted pair (UTP) wiring, up to 100 meters long. The cable is thinner and more flexible than the coaxial cable used for the 10Base- 2 or 10Base- 5 standards. Cables in the 10Base- T system connect with RJ-45 connectors. A star topology is common with 12 or more computers connected directly to a hub. 100Base- TX (IEEE 802.3u) – known as Fast Ethernet, This has either two pairs of unshielded twisted pairs (UTP) category 5 wires or two shielded twisted pairs (STP) type 1 wires. One of these pairs transmits frames from hub to the device and the other pair transmits from device to hub, thus providing full- duplex communication Each network segment can have maximum length of 100m (328ft) 100Base- FX (IEEE 802.3u) – a version of Fast Ethernet that uses multi- mode optical fiber. This has two pairs of optical fibers. One pair transmits frames from hub to the device and the other from device to hub. Maximum distance between hub and station is 2000m. ***Note:1000Base- T means that the speed of the network is up to 1000 Mbps, baseband signaling is used, and the twisted- pair cabling will be used (T stands for twisted-pair).

132. 1000Base- CX (IEEE 802.3z) The initial standard for Gigabit Ethernet Uses shielded copper twisted- pair cabling with DE- 9 or 8P8C connector Maximum segment length is 25 metres 1000Base- SX (IEEE 802.3z) – 1 Gigabit Ethernet running over multimode fiber- optic cable. Uses a pair of fibre optic cables of a shorter wavelength having 770 – 860 nm diameter The maximum segment length varies from 220 – 550 metres. 1000Base- LX (IEEE 802.3z) – 1 Gigabit Ethernet running over single- mode fiber Uses a pair of fibre optic cables of a longer wavelength having 1270 – 1355 nm diameter Maximum segment length is 500 metres Can cover distances up to 5 km 1000Base- T (IEEE 802.3ab) – Gigabit Ethernet that uses Category 5 UTP wiring Uses a pair four lanes of twisted- pair cables (Cat- 5, Cat- 5e, Cat- 6, Cat- 7) Maximum segment length is 100 metres 10G Base- T (802.3.an) – 10GBASE- T is a type of Ethernet signaling providing speeds over twisted- pair cabling that go beyond 1 Gigabit per second (Gbps) for distances up to 100 meters. This IEEE 802.3an standard can reach 2.5 and 5 Gbps over Cat5e and Cat6 cabling. Depending upon the network infrastructure, signals can potentially reach new speeds of up to 10 Gbps.

133. Types of Ethernet Networks 1.Fast Ethernet The fast Ethernet is a type of Ethernet network that can transfer data at a rate of 100 Mbps using a twisted- pair cable or a fiber- optic cable. The older 10 Mbps Ethernet is still used, but such networks do not provide necessary bandwidth for some network- based video applications. Fast Ethernet is based on the proven CSMA/CD Media Access Control (MAC) protocol, and uses existing 10BaseT cabling. Data can move from 10 Mbps to 100 Mbps without any protocol translation or changes to the application and networking software Gigabit Ethernet The Gigabit Ethernet is a type of Ethernet network capable of transferring data at a rate of 1000 Mbps based on a twisted- pair or fiber optic cable, and it is very popular. The type of twisted- pair cables that support Gigabit Ethernet is Cat 5e cable, where all the four pairs of twisted wires of the cable are used to achieve high data transfer rates. The 10 Gigabit Ethernet is a latest generation Ethernet capable of transferring data at a rate of 10 Gbps using twisted- pair or fiber optic cable.

134. 10 Gigabit Ethernet 10 Gigabit Ethernet is the latest generation and delivers a data rate of 10 Gbit/s (10,000 Mbit/s), and a fiber optic or twisted pair cable can be used. 10GBASE- LX4, 10GBASE- ER and 10GBASE- SR based on an optical fiber cable can be used to bridge distances of up to 10,000 m (6.2 miles). With a twisted pair solution, a very high quality cable (Cat- 6a or Cat- 7) is required. 10 Gbps Ethernet is mainly used for backbones in high-end applications that require high data rates. Switch Ethernet Multiple network devices in a LAN require network equipment's such as a network switch or hub. When using a network switch, a regular network cable is used instead of a crossover cable. The crossover cable consists of a transmission pair at one end and a receiving pair at the other end The network switch normally supports different data transfer rates. The most common data transfer rates include 10 Mbps – 100 Mbps for fast Ethernet, and 1000 Mbps – 10 Gbps for the latest Ethernet. Switch Ethernet uses star topology, which is organized around a switch. The switch in a network uses a filtering and switching mechanism similar to the one used by the gateways, in which these techniques have been in use for a long time.

135. Ethernet- Protocol stack

136. How does Ethernet work? When communicating over a data network, the Ethernet system divides the data into a set of what are termed frames. These frames have a specific format and each one contains the source and destination addresses. The frame also contains information for error checking so that any data that is corrupted can be detected. If errors are detected then typically the higher layers of the protocol stack for the system will discard the data and request a re- transmission. Ethernet adopts the OSI model for its protocol stack and in line with this, Ethernet itself provides services up to Layer 3, the data link layer Ethernet has adopted the 48 bit MAC address format that has also been used by other IEEE 802 standards

137. IEEE 802.3 Physical layer Physical layer 10Base5/10base 2 10Base T 100Base TX/100 BASE FX 1000Base CX/SX/LX/T 10G Base T 802.3 802.3 802.3u 802.3z and 802.3ab 802.3an Ethernet Fast Ethernet Gigabit Ethernet 10Gigabit Ethernet

138. Ethernet MAC data frame format The basic Ethernet frame in use today is referred to as the Ethernet type II frame. This is the frame format developed by the layer 2 elements of the stack, and this is then passed to the layer 1 physical layer to put it into the format for sending. The layer 2 format consists of the main elements of the data frame, but without some headers needed for the actual sending of the overall data In order to send the data over the Ethernet link, some additional elements need to be added to the basic MAC data frame so that the data can be pre- transmitted.

139. The basic frame consists of seven elements split between three main areas:- Header Preamble / SFD: - this element within the header is added by the layer 1 part of the protocol stack. It enables the receiver to synchronize and know that a data frame is about to be sent. Preamble (PRE ) - This is seven bytes long and it consists of a pattern of alternating ones and zero, and this informs the receiving stations that a frame is starting as well as enabling synchronization. Start of Frame Delimiter (SFD) - This consists of one byte and contains an alternating pattern of ones and zero but ending in two ones. Destination Address (DA ) - This field contains the address of station for which the data is intended. The left most bit indicates whether the destination is an individual address or a group address. An individual address is denoted by a zero, while a one indicates a group address. The next bit into the DA indicates whether the address is globally administered, or local. If the address is globally administered the bit is a zero, and a one of it is locally administered. There are then 46 remaining bits. These are used for the destination address itself. Source Address (SA ) - The source address consists of six bytes, and it is used to identify the sending station. As it is always an individual address the left most bit is always a zero. Length / Type - This field is two bytes in length. It provides MAC information and indicates the number of client data types that are contained in the data field of the frame. It may also indicate the frame ID type if the frame is assembled using an optional format.(IEEE 802.3 only).

140. Payload User Data - This block contains the payload data and it may be up to 1500 bytes long. If the length of the field is less than 46 bytes, then padding data is added to bring its length up to the required minimum of 46 bytes. Later implementations allowed for so- called ‘jumbo’ frames up to 9,000 bytes long to facilitate certain types of large traffic flows such as file transfers and video links. Trailer Frame Check Sequence (FCS) - This field is four bytes long. It contains a 32 bit Cyclic Redundancy Check (CRC) which is generated over the DA, SA, Length / Type and Data fields. After the Ethernet data frame itself there is an inter- frame gap of a minimum of 12 bytes of data. This acts as a delimiter to ensure that the receiver knows the frame is complete before any further data is sent. The CSMA/CD protocol This access method involves the use of CSMA/CD and it was developed to enable several stations to share the same transport medium without the need for switching, network controllers or assigned time slots. Each station is able to determine when it is able to transmit and the network is self organizing

141. The CSMA/CD protocol used for Ethernet and a variety of other applications falls into three categories. The first is Carrier Sense . Here each station listens on the network for traffic and it can detect when the network is quiet. The second is the Multiple Access aspect where the stations are able to determine for themselves whether they should transmit. The final element is the Collision Detect element. Even though stations may find the network free, it is still possible that two stations will start to transmit at virtually the same time. If this happens then the two sets of data being transmitted will collide. If this occurs then the stations can detect this and they will stop transmitting. They then back off a random amount of time before attempting a retransmission. The random delay is important as it prevents the two stations starting to transmit together a second time.

142. The standard for wireless networking within a home or office. Also known as a "Wi- Fi" or "802.11" network, wireless Ethernet is the wireless counterpart to regular, wired Ethernet, which is also the standard for local networks. Ethernet networks can also be wireless. Rather than using Ethernet cable to connect the computers, wireless NICs use radio waves for two- way communication with a wireless switch or hub. It consists of Ethernet ports, wireless NICs, switches and hubs. Wireless network technology can be more flexible to use, but also require extra care in configuring security. Wireless Ethernet

143. Advantages of Ethernet connection: ➨ It is inexpensive to form Ethernet based network of computers. ➨ The nodes on Ethernet network have same privileges and do not follow client- server architecture. ➨ It is easy to maintain and troubleshoot the Ethernet network. ➨ The cables used in Ethernet connection are immune to noise and hence quality of connection is maintained without any degradation. ➨ With latest versions such as gigabit Ethernet and wireless Ethernet (IEEE 802.11ac/11ad) transfer speeds in Gbps have become possible Disadvantages of Ethernet connection: ➨ As it is not designed to support real time voice and video traffic initially, it works best for traffic consisting of data solely. ➨ The Ethernet network does not prioritize traffic in order to support effective class of service. ➨ The gigabit Ethernet is still not in use at many places and hence will take time for common man to have benefits of this Ethernet version. ➨ The 100Base- T4 version requires 4 pair of wiring to support data transfer. Moreover it can not support full duplex data communication mode.

144. 7.IEEE 1394 Fire wire - contents IEEE 1394 Fire wire Introduction History IEEE 1394 - Standards and versions How It Works Advantages Dis-Advantages Applications

145. 7.IEEE 1394 Fire wire - Introduction IEEE 1394, High Performance Serial Bus, is an electronics standard for connecting devices to your personal computer. IEEE 1394 provides a single plug-and- socket connection on which up to 63 devices can be attached with data transfer speeds up to 400 Mbps.(latest 800Mbps) The standard describes a serial bus or pathway between one or more peripheral devices and computer's microprocessor . Many peripheral devices now come equipped to meet IEEE 1394. Two popular implementations of IEEE 1394 are Apple's FireWire and Sony's i.LINK . IEEE 1394 implementations are expected to replace and consolidate today's serial and parallel interfaces, including Centronics parallel , RS- 232C , and Small Computer System Interface ( SCSI ). The first products to be introduced with FireWire include digital camera s, digital video disks ( DVD s), digital video tapes, digital camcorders, and music systems. IEEE 1394 is a peer- to- peer interface, one camcorder can dub to another without being plugged into a computer. With a computer equipped with the socket and bus capability, any device (for example, a video camera) can be plugged in while the computer is running

146. Michael Johas Teener , original chair and editor of the IEEE 1394 standards document, and technical lead for Apple's FireWire team from 1990 until 1996 The original FireWire project name was " Chefcat ", the name of Michael Teener's favorite coffee cup FireWire is a trademark of Apple Computer, Inc . The trademark was filed in 1993. The "FireWire" name was chosen by a group of engineers socializing before Comdex 1993, just before the project was about to going to the public. It was developed by the IEEE P1394 Working Group , largely driven by contributions from Sony(102 patents), Apple (58 patents), and Panasonic (46 patents), in addition to contributions made by, engineers from Philips, LG Electronics, Toshiba, Hitachi, Canon INMOS/SGS Thomson (now STMicroelectronics) and Texas Instruments. In 2007, IEEE 1394 was a composite of four documents: the original IEEE Std. 1394–1995 , the IEEE Std. 1394a- 2000 amendment, the IEEE Std. 1394b-2002 amendment, and the IEEE Std. 1394c- 2006 amendment. On June 12, 2008, all these amendments as well as errata and some technical updates were incorporated into a superseding standard, IEEE Std. 1394–2008 . Sony's implementation of the system, i.LINK , used a smaller connector with only four signal conductors, omitting the two conductors that provide power for devices in favor of a separate power connector. This style was later added into the 1394a amendment. This port is sometimes labeled S100 or S400 to indicate speed in Mbit/s. IEEE 1394 Fire wire- History

147. FireWire 400 (IEEE 1394-1995) The original release of IEEE 1394- 1995 specified what is now known as FireWire 400. It can transfer data between devices at 100, 200, or 400 Mbit/s half- duplex data rates. These different transfer modes are commonly referred to as S100, S200, and S400. Cable length is limited to 4.5 metres (14.8 ft), although up to 16 cables can be daisy chained using active repeaters; external hubs or internal hubs are often present in FireWire equipment. The S400 standard limits any configuration's maximum cable length to 72 metres (236 ft). FireWire 400 (IEEE 1394a- 2000) An amendment, IEEE 1394a, was released in 2000, which clarified and improved the original specification. It added support for asynchronous streaming, quicker bus reconfiguration, packet concatenation, and a power- saving suspend mode. IEEE 1394a offers a couple of advantages over the original IEEE 1394–1995. 1394a is capable of arbitration accelerations , allowing the bus to accelerate arbitration cycles to improve efficiency. It also allows for arbitrated short bus reset , in which a node can be added or dropped without causing a big drop in isochronous transmission. 1394a also standardized the 4-conductor alpha connector developed by Sony and trademarked as " i.LINK ", already widely in use on consumer devices such as camcorders, most PC laptops, a number of PC desktops, and other small FireWire devices. The 4-conductor connector is fully data- compatible with 6- conductor alpha interfaces but lacks power connectors. IEEE 1394 - Standards and versions

148. FireWire 800 (IEEE 1394b-2002) IEEE 1394b-2002 introduced FireWire 800 (Apple's name for the 9-conductor "S800 bilingual" version of the IEEE 1394b standard) FireWire 800's connector, referred to as a beta connector, is different from FireWire 400's alpha connectors, making legacy cables incompatible. The full IEEE 1394b specification supports data rates up 400Mbps over beta- mode or optical connections up to 100 metres (330 ft) in length. The original 1394 and 1394a standards used data/strobe (D/S) encoding (renamed to alpha mode ) with the cables, while 1394b added a data encoding scheme called 8B10B referred to as beta mode . FireWire S800T (IEEE 1394c-2006) IEEE 1394c- 2006 was published on June 8, 2007. It provided a major technical improvement, namely new port specification that provides 800 Mbit/s over the same 8P8C (Ethernet) connectors with Category 5e cable, which is specified in IEEE 802.3 clause 40 (gigabit Ethernet over copper twisted pair) along with a corresponding automatic negotiation that allows the same port to connect to either IEEE Std 1394 or IEEE 802.3 (Ethernet) devices.

149. FireWire S1600 and S3200 The 1394 Trade Association announced that products would be available before the end of 2008 using the S1600 and S3200 modes that, for the most part, had already been defined in 1394b and were further clarified in IEEE Std. 1394–2008. The 1.5 Gbit/s and 3 Gbit/s devices use the same 9-conductor beta connectors as the existing FireWire 800 and are fully compatible with existing S400 and S800 devices. It competes with USB 3.0. S1600 (Sym- wave) and S3200 (Dap Technology) development units have been made, however because of FPGA technology Dap- Technology targeted S1600 implementations first with S3200 not becoming commercially available until 2012. Steve Jobs declared FireWire dead in 2008.As of 2012, there were few S1600 devices released, with a Sony camera being the only notable user. Future enhancements (including P1394d) A project named IEEE P1394d was formed by the IEEE on March 9, 2009 to add single mode fiber as an additional transport medium to FireWire. The project was withdrawn in 2013. Other future iterations of FireWire were expected to increase speed to 6.4 Gbit/s and additional connectors such as the small multimedia interface.

150. How It Works There are two levels of interface in IEEE 1394, one for the backplane bus within the computer and another for the point- to- point interface between device and computer on the serial cable. The backplane bus supports 12.5, 25, or 50 megabits per second data transfer. The cable interface supports 100, 200, or 400 megabits per second. Each of these interfaces can handle any of the possible data rates and change from one to another as needed. IEEE 1394 provides two types of data transfer: asynchronous and isochronous. Asynchronous is for traditional load- and-store applications where data transfer can be initiated and an application interrupted as a given length of data arrives in a buffer. Isochronous data transfer ensures that data flows at a pre- set rate so that an application can handle it in a timed way. For multimedia applications, this kind of data transfer reduces the need for buffering and helps ensure a continuous presentation for the viewer. FireWire can work with the latest internal computer bus standard, Peripheral Component Interconnect (PCI), but higher data transfer rates may require special design considerations to minimize undesired buffering for transfer rate mismatches.

151. Implementation cost of IEEE 1394 is low Cabling system is adaptable Provides higher bandwidth Transfer rates are high Very efficient Supports current versions of Windows Supports isochronous data transfer Supports customization Provides throughput of 400 megabits per second Provides low latency It is PC independent Easy to use Capability of Plug and play Most of them do not require external power supply Advantages

152. disadvantages Slower data transfer rate - up to 400 Mbps for 1934a and up to 800 Mbps for 1394b (dependent on camera, IEEE 1394 interface hardware, and operating system support) No onboard memory for saving images Less triggering support Difficult to synchronize with other devices Not all PCs come factory equipped with Fire- wire ports. Fire- wire devices are typically more expensive than USB devices

153. Consumer automobiles IDB-1394 Customer Convenience Port (CCP) was the automotive version of the 1394 standard Consumer audio and video IEEE 1394 was the High- Definition Audio- Video Network Alliance (HANA) standard connection interface for A/V (audio/visual) component communication and control. Military and aerospace vehicles SAE Aerospace standard AS5643 originally released in 2004 and reaffirmed in 2013 establishes IEEE-1394 standards as a military and aerospace data- bus network in those vehicles. General networking FireWire can be used for ad- hoc (terminals only, no routers except where a FireWire hub is used) computer networks. Specifically, RFC 2734 specifies how to run IPv4 over the FireWire interface, and RFC 3146 specifies how to run IPv6. Instrumentation & Industrial Digital Camera Digital Video (DV) is a standard protocol used by some digital camcorders iPod and iPhone synchronization and charging Applications