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CHAPTER Serial and Parallel Communication

CHAPTER Serial and Parallel Communication. Chapter Objectives. Explain serial communication Standards, ports, resources etc. Show a few examples of serial communication connections used in practice Describe the features of parallel communication Standards, use etc. Chapter Modules.

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CHAPTER Serial and Parallel Communication

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  1. CHAPTER Serial and Parallel Communication

  2. Chapter Objectives • Explain serial communication • Standards, ports, resources etc. • Show a few examples of serial communication connections used in practice • Describe the features of parallel communication • Standards, use etc.

  3. Chapter Modules • Serial communication • Newer serial communication technologies • Serial communication connections • Parallel communication

  4. Module Serial Communication

  5. Chapter Objectives • Explain serial communication • Standards, ports, resources etc. • Show a few examples of serial communication connections and ports used in practice

  6. Definition of Serial Communication Travels in series A B Bit by bit transmission of information in series

  7. Serial Communication Implementation • Popular implementation found in older and some newer computers is known as the RS-232 serial connection found in microcomputers • Newer type of serial connections • Universal Serial Bus (USB) • IEEE 1394 serial connection that is also known as the FireWire connection

  8. Other Serial Communication Technologies • eSATA • Fiber channel

  9. RS-232C Serial Standard • The most popular standard • Conforming serial ports are found in the following • Micro • Minis and mainframes • Sometimes these ports are also known as the asynchronous ports or asnch ports in short • It is also possible to conduct synchronous transmission through these ports as well

  10. Purpose of the Serial Ports Parallel Digital Data Expansion Bus Serial Interface In Out Serial Digital Data

  11. Standard Serial Port on a Computer (DB 9)

  12. Serial Port Identification Source: Black Box

  13. Male and Female Connectors Holes Pins Typical parallel port Typical serial port Source Black Box

  14. Differentiating Between Serial and Parallel Ports Parallel Female Port Serial Male Port

  15. Serial Cable DB9 Connector DB25 Connector Source Black Box

  16. End of Module

  17. Module Resources for Serial Ports

  18. Support for Serial Ports • Both hardware and software support are required for the functioning of serial ports • A microcomputer is supplied with two standard serial ports • Additional ports can be installed

  19. Operating System Support • Earlier operating systems • Supported four serial ports • Today’s operating systems • Support a larger number of serial ports • For most practical purposes, four serial ports are considered sufficient in a microcomputer • Only two, namely com1 and com2, are in widespread use

  20. Port Properties Com 1 • IRQ • I/O Address • Base Memory Address • Direct Memory Address (DMA) Channel Com2 Com3 Com4

  21. Assignment of Values • The assignment of the respective values for each port must be unique • An IRQ, I/O address or DMA conflict can lead to a disruption in the execution of an application • This is no more a problem with newer OS and hardware

  22. IRQ and Address Assignment PORT IRQ ADDRESS ------------------------------------------------------------ 1 4 3F8-3FF 2 3 2F8-2FF 3 4 These values should not normally be changed.

  23. End of Module

  24. Module Faster RS-232 Serial Ports and Summary

  25. Older and Newer Serial Ports • Older serial ports operated at a slower speed • The newer serial ports operate at a faster speed • The newer serial ports are equipped with a new processor • The hardware in question is known as the UART processor

  26. Enhanced Serial Ports Universal Asynchronous Receiver Transmitter (UART) UART 16550/ 16650 Com. Port The newer processor is required for communication at speeds of 115,200 bps

  27. ISDN Line Requirement • In theory, the maximum speed over a single ISDN line is approximately 128K bps • If necessary, enhanced serial ports can be installed by installing a board containing the enhanced ports

  28. UART-based Ports

  29. In Summary • Two standard serial ports are present on a microcomputer • Resources • IRQ, I/O Address and DMA • Port settings • Communication speed, length of the data bits etc. • Later versions of the UART chip are required to support high speed communication through the serial port

  30. End of Module

  31. Module Newer Serial Communication Technologies: Universal Serial Bus (USB)

  32. Universal Serial Bus • Being introduced as a high-speed “replacement” for the traditional RS-232 port • USB has higher bandwidth • 1.5 Mbps, 12 Mbps and 480 Mbps • Faster than the RS-232 port that operates in the region of 115+ K bps • Devices can be daisy-chained

  33. Daisy Chaining of USB Devices Device 3 USB Connection Computer USB Port Device 2 In Device 1 Out

  34. Connecting USB Devices Using a Hub Device 3 USB Connection Computer USB Port Device 2 In Hub Out

  35. Sample USB Devices • Keyboards • Monitors • Digital Cameras • Digital Vide Recorders • etc.

  36. USB Standards • USB 1.1 • USB 2.0 • USB On-The-Go (OTG) • A newer standard being designed for portable and small devices

  37. U3 Standard

  38. USB Connectors • Type A • Upstream connectors • From the system • Type B • Downstream connectors • To the device • Mini A • Mini B • Smaller connector for PDAs, mobile phones and digital cameras • mini-A and mini-B and mini-AB • Small for factor connectors for USB OTG

  39. Support for the Deployment of USB in Microcomputers • There are two requirements for USB implementation • One is the presence of USB hubs to support USB ports on the microcomputer • The other is the support required from the operating system to operate the USB • Most motherboards now have built-in support for USB • Not all versions of the Windows OS support for USB

  40. Operating System Support for USB • The newer operating systems such as Windows XP or the later versions of some of the older operating systems support USB • Windows 98 • Windows 95 OSR2 • In accordance with USB standards, these operating systems support hot plug-and-play for USB devices

  41. Hot Plug-and-Play • The ability to connect a device to the computer while a computer is in operation • As the device is connected, the OS would: • Recognize the device • Configure the device • There is no manual intervention in the above process

  42. Advantages of USB Over the RS-232 Port • Higher speed • Ability to daisy chain different devices • Support for hot plug-and-play

  43. End of Module

  44. Module IEEE 1394 FireWire Connection

  45. IEEE 1394 Standard (FireWire) • In some ways, it competes with USB • Bandwidth is 400M bps or 50M Bps • In theory therefore, it can replace older SCSI and IDE used for connecting hard disks • FireWire’s impact is most likely to be felt in multimedia applications involving audio and video • Some basic networking can be done through the Firewire ports as well

  46. Data Transmission • 100 Mbps, 200 Mbps and 400 Mbps • Newer ports are being developed to support 800 Mbps and 1600 Mbps • Data is transmitted in packets and it is available to all the devices on the bus

  47. Networking with Firewire • 1394 supports peer-to-peer networks based on point-to-point connections • Computers can be networked in a peer-to-peer architecture using the Firewire port

  48. Type of Transmission • Asynchronous (bulk) transfer - guarantees correct transmission; suitable for control data and where error-free transmission takes precedence over speed. • Isochronous transfer - guarantees bandwidth (ideal for transmitting time critical data, e.g. video, audio) • Courtesy: www.thesycon.de

  49. The maximum distance between nodes is 4.5 m (revisions to the standard will support distances of • 100 m between nodes • Up to 27 devices can be connected to each node. • Courtesy: www.thesycon.de

  50. “Hot-swapping“ allows users to attach and detach devices while the network is running; the network is reconfigured automatically. • Each bus supports up to 64 nodes and the specification supports up to 1024 buses. • A 1394 bus appears as a flat space in memory, with each node occupying a 48 bit address range. • Integrated power supply - devices receive power through the bus. • Courtesy: www.thesycon.de

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