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Serial Interfaces. Bit serial bus. New generation of busses Uses bit-serial, differential drive technology Uses on-line device drivers (Hot-plug technology) Automatically detects plugged in devices and configures the controlling software Two main tech : USB and Firewire.
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Bit serial bus • New generation of busses • Uses bit-serial, differential drive technology • Uses on-line device drivers (Hot-plug technology) • Automatically detects plugged in devices and configures the controlling software • Two main tech : USB and Firewire
USB : Universal Serial Bus vdd,gnd • 12 Mb/s serial bus • Hot-plug tech (plug & play) • Supports up to 127 external devices • Provides power • USB 2.0 : 480 Mb/s serial bus D+, D-
Bus topology • Tiered star structure, up to tier 6
USB devices • HUB • Serve to USB connectivity • Can detect attach and detach • Hub Controller + Hub repeater • Functions • USB device that is able to transmit or receive data
USB host • Client • Describes all the software entities that are responsible for USB devices • USB System • Translation between the client data and USB transaction on the interconnect • Managing USB resources(bandwidth, power …) • USB Bus interface • Handles interactions for the electrical protocol layer
Type of transaction • Direction of trans. • USBdevice address token Bus Protocol • Host controller initiates data transfer by generating ‘token packet’ • Data transferred • Handshake packet for completion data transfer handshake
Remove indicator indicator device • Enable port • allocate USB address disable Attach and Remove of USB Devices Host Hub upstream port port port port
Data flow types • Control transfers • configure device at attach time • Bulk data transfers • generate or consume large data. error detection and retries used ex) file Xfer • Interrupt data transfers • Small, limited latency transfer ex) event notification, echo from device • Isochronous data transfers • Continuous and irregular data. ex) voice
Firewire • 400 Mbps ( 3200Mbps for 1394b ) • Plug & play • Support 63 devices • Provides power • Comparison to USB • USB is host-based(must be connected to computer), Firewire is peer to peer (two devices can be connected directly)
Website • http://www.usb.org • http://www.apple.com/firewire