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Universal Serial Bus

Universal Serial Bus. Jordan Weichel Jacob Lucero Tony Lucchesi. Outline. Overview Design Interface Power. http://www.brandsoftheworld.com/search?query_id=3996676&page=1&mtype=&brand_id=22618. History. USB 1.0 Full Speed 12 Mbits /s (1.5 MB/s ) Low Speed 1.5 Mbits /s (0.2 MB/s)

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Universal Serial Bus

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  1. Universal Serial Bus Jordan Weichel Jacob Lucero Tony Lucchesi

  2. Outline • Overview • Design • Interface • Power http://www.brandsoftheworld.com/search?query_id=3996676&page=1&mtype=&brand_id=22618

  3. History • USB 1.0 • Full Speed 12 Mbits/s (1.5 MB/s) • Low Speed 1.5 Mbits/s (0.2 MB/s) • 1996 • USB 1.1 (1998) • USB 2.0 • High Speed 480 Mbits/s (60 MB/s) • 2000 • USB 3.0 • SuperSpeed 5.0 Gbits/s (625 MB/s) • 2008 http://www.legitreviews.com/article/1150/1/

  4. USB in Embedded Systems • Self powered • Fast communication • Most reliable way to talk to computers

  5. USB Wires and Ports http://i.imgur.com/XwIqQ.jpg http://commons.wikimedia.org/wiki/File:Types-usb_new.svg

  6. High-level Design http://www.l-com.com/images/usb-tutorial-tier-topology.gif

  7. Endpoints • Endpoints • 32 per device • (Device_addr, endpoint_num) http://www.mightyape.co.nz/product/Canyon-Full-HD-1080P-Webcam-with-Mic/20977976/images/14450845/

  8. Pipes • Message pipes • Control • Short and simple for commands and queries • Stream pipes • Interrupt • Small bounded latency for quick transfers • Bulk • Large transfers use remaining bandwidth • Isochronous • Guaranteed data rate

  9. Process • Enumeration • Host assigns each device an address • Host acquires stream transfer types • Post enumeration http://upload.wikimedia.org/wikipedia/commons/1/1b/USB_pipes_and_endpoints_%28en%29.svg Picture from beyster 1695 p28

  10. USB Protocols • Token Packet • Initiatiates communication • Data Packet • Contains information /payload • Status Packet • Acknowledges transactions • Reports errors

  11. Transaction

  12. USB to UART Example Data Out USB VCC(+5v) Data In Data- Data+ USB GND https://www.sparkfun.com/products/650

  13. Power Pins http://1.bp.blogspot.com/-6nvzXThVlNU/T9pnBRiSr-I/AAAAAAAAB0o/MFVOHHENVbk/s1600/pin-out-usb3_usb2A.jpg

  14. Vocabulary • 100 mA = 1 unit load • Vbus= VCC • 500 mA max draw from Vbus per device • 5 V goal • Source • Powered vs. unpowered

  15. Power Overview • Low-power • High-power • Self-power http://mac-ave.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/3/1/31joqfxn1yl._sl500_aa300_.jpg

  16. Low-Power Functions • Max draw • 1 unit load (100 mA) • Power comes exclusively from Vbus • Voltage • 4.40 V min • 5.25 V max

  17. High-Powered Functions • Max draw • 5 unit loads (500 mA) • Power comes exclusively from Vbus • Voltage • 4.40 V min • 5.25 V max

  18. Self-Powered Functions • 1 unit load from Vbus • Rest of the power from external source • Requires safety catch to never draw more than 1 unit load from Vbus

  19. Power Hiccups • Suspended devices • Draw no more than 500 µA • Vbus unstable • Devices are plugged / unplugged • Transient voltage dips as low as 4.1 V • Need to design device to handle situation

  20. Pros and Cons Universal transfer protocol Increased reliability and speed of data transfers Pre-implemented drivers Many devices per host Dedicated hardware Complex debugging http://2.bp.blogspot.com/-RSVGM9fJSBQ/Tk-yHnrC7BI/AAAAAAAAAfU/9by6cOS5U1o/s1600/Parallel-Port.jpg

  21. Questions?

  22. References http://www.pcworld.com/article/156494/superspeed_usb.html http://computer.howstuffworks.com/usb3.htm http://www.beyondlogic.org/usbnutshell/usb2.shtml http://www.l-com.com/content/USB-Tutorial.html http://www.wisegeek.org/what-are-the-advantages-of-usb-30.htm http://uk.farnell.com/images/en/ede/pdf/usb_dev_mistake.pdf http://www.usb.org/home http://www.smxrtos.com/articles/usb_art/waysusb.htm https://www.sparkfun.com/datasheets/IC/FT232R_v104.pdf

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