compdsp_Burk_USB_Fun..
Upcoming SlideShare
Loading in...5
×
 

compdsp_Burk_USB_Fun..

on

  • 1,242 views

 

Statistics

Views

Total Views
1,242
Views on SlideShare
1,242
Embed Views
0

Actions

Likes
1
Downloads
56
Comments
0

0 Embeds 0

No embeds

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment
  • “H” means sent by the host, “D” means sent by the device.

compdsp_Burk_USB_Fun.. compdsp_Burk_USB_Fun.. Presentation Transcript

  • USB Fundamentals and Applications for Digital Signal Processing Greg Burk J. Gordon Electronic Design [email_address] 7/30/2004
  • Agenda
      • USB Specifications
      • USB Basics
      • Components
      • Onion introduction
        • Signaling
        • Packets
        • Transfers
        • Requests
        • Operating System Interface
      • Considerations for DSP Applications
      • USB Resources
  • USB Specifications
    • USB 1.0 – The original spec, superseded quickly by USB 1.1
    • USB 1.1 – Minor enhancements to the USB 1.0 spec, supported Low and Full speed devices
    • USB 2.0 – The Current Standard, added “high speed’ to USB 1.1
    • USB OTG – USB On-the-Go, a supplement to the USB 2.0 spec that added a form of device to device communications.
    • WUSB – Wireless USB, a work in progress -- not a standard yet
    View slide
  • USB Founding Companies Philips Northern Telecom HP DEC Lucent IBM NEC NEC Microsoft Microsoft Intel Intel Compaq Compaq USB 2.0 USB 1.0 View slide
  • USB 2.0 in a Nutshell
      • Runs 40X faster than USB 1.1
        • Low speed: 1.5Mb/s
        • Full speed: 12Mb/s
        • High speed: 480Mb/s
      • Fully supports existing USB devices
        • Forward compatible—plug existing 1.1 devices into new 2.0 hosts
        • Backward compatible—plug new 2.0 devices into existing 1.1 hosts
      • Uses the same cables as USB 1.1
  • USB On-the-Go (USB OTG)
    • Connect two ‘peripherals’ together
      • PC is not required (but still supported)
    • Allow peripherals to wake up hosts
    • Allow two devices to exchange the host role
    • New OTG devices can tap into the existing 900 million USB devices
  • USB OTG Example Applications Source: Beeman: www.usbonthego.com Exchange pictures Upload pictures to web Print pictures Camera Cell Phone Printer Camera Exchange songs MP3 player MP3 player Exchange Contact info Print call info Upload pictures to web Cell Phone Printer Camera Cell Phone Synchronize phone list, meetings Upload pictures Download songs Cell Phone Camera MP3 player PC Applications Peripheral Host
  • USB OTG Details
    • Defines a new connector and cable
      • “ Mini AB” receptacle
      • Mini-A to Mini-B cable
      • Cable establishes the default host
        • A-Device is the default host
    • Dual-role USB devices:
      • Are sometimes a peripheral, sometimes a host
      • Must use the new AB connector
      • Provide limited host capability
        • Targeted peripheral list
      • Operate at full speed (high speed optional)
  • Wireless USB (WUSB)
    • Specification currently under development (expected release early 2005)
    • Key players are: Intel, Microsoft, HP, NEC, Phillips Semiconductors, Agere Systems, and Samsung Electronics
    • Based on Ultra-wideband (UWB) standard
    • Supposed to support USB 2.0 bandwidth (480 Mb/s) at distances of up to 10 meters
    • Projected Feature Set:
      • Compatibility with USB 2.0 Standard
      • Security at same level as wired USB
      • Connections up to 127 WUSB device
    • For More info see: http://www.intel.com/labs/wusb/
    • (This is NOT the same as Cypress Semiconductors Wireless USB)
  • USB Basics
  • USB Basics
      • USB is a Master/Slave Polled Bus (PC is the “Master”, Devices are the “Slaves”)
      • USB has a “tiered star” architecture that can USB can support up to 126 devices
        • 7-bit address = 128 – root hub – reserved addr 0 for enumeration
      • USB is “Hot Pluggable”
      • USB connections can provide both data and power to the devices
  • USB is not Simple
      • Outside, it is simple
      • The “rich user experience” requires some inner complexity
      • Even though it replaces serial and parallel ports, it’s not a drop-in replacement
      • It’s electrically simple, but a whole protocol layer is added
  • USB Projects Can Require a Significant Code Development Effort
      • Device side
        • USB houskeeping firmware
        • Application firmware
      • Host side
        • Driver (maybe)
        • Application software
  • USB Components
  • Components of USB Systems
    • USB Host Controllers
    • USB Hubs
    • USB Cables
    • USB Peripheral Devices
  • USB Host Controllers
    • Reside in PC on motherboard or add-in card
    • Are the “master” device on the USB bus
    • Host Controller has integral “Root Hub”
    • Host Controller Interfaces:
        • Universal Host Controller Interface (UHCI)
        • Open Host Controller Interface (OHCI)
        • Enhanced Host Controller Interface (EHCI)
  • USB Cables
      • Transport both Data and Power
      • Four wires: Vbus, GND, D+, D–
      • Cables are 5 meters MAX
      • Two connector types, “A” and “B”
        • Prevents illegal topologies
        • “ A” connectors are the ones that goes to the PC or Hub, “B” connectors goes to the device) (OTG adds Miny A and Mini B connectors)
      • Cables can be either “captive” (like mice) or detachable
      • Cables can be unshielded (Low speed devices) or shielded (Full Speed and High Speed devices)
      • USB extension cables are ILLEGAL
  • USB Hubs
    • A hub provides additional connection points (ports) for devices
    • Hubs can be:
        • Self-Powered (<= 500ma to each device)
        • Bus-Powered (<= 100mA to each device)
    • Hubs contain most of the “magic” and differences between USB 1.1 and USB 2.0
  • USB Devices
    • Devices can be:
        • Self-Powered
          • External Power Source (i.e. wall wart)
          • Batteries
        • Bus-Powered
          • Low Power Bus Powered (<= 100mA)
          • High Power Bus Powered >100mA, <=500mA)
    • Devices are “self describing”
        • Devices return data (USB descriptors) to host to indicate its capabilities, configurations, and how the device is able to communicate
  • Compound and Composite Devices
    • Composite Device
      • Multiple interfaces, independently controlled
        • Each interface can have a different driver
    • Compound Device
      • Collection of separate functions, each with a USB address, connected to an internal hub
      • Example: Keyboard & Trackball in same package
  • USB is a Polled BUS
      • The Host (PC) initiates all transfers
      • Devices respond to host requests
      • Direction: OUT is host-to-device
      • Direction: IN is device-to-host
      • USB is NOT peer-to-peer (not even in USB OTG)
  • USB Topology PC USB USB “ Tiered Star” Hub USB USB USB USB PC USB USB Device Device Device Device Device
  • USB Transfer Speeds
      • USB 1.1:
        • Low speed is 1.5Mb/s
        • Full speed is 12Mb/s
      • USB 2.0
        • Low speed is 1.5Mb/s
        • Full speed is 12Mb/s
        • High speed is 480 Mb/s
        • There is a VERY common misconception that say a device is USB 2.0 compliant that it means that it is High Speed device. It does NOT!
  • Endpoints
      • USB Spec: “a source or sink of data”
        • A Control Transfer Type endpoint is bi-directional
        • Others are uni-directional
      • Four address bits plus a direction bit selects between up to 32 buffers (FIFOs)
      • Different USB chips support
        • Various numbers of endpoints
        • Various buffer sizes
      • Each device must have 1 Control Type Endpoint (Commonly referred to as Endpoint 0 or the Default Endpoint)
  • Pipes
    • An abstraction used by the USB spec used to indicate that 2 endpoints are joined (one in the PC Host and the other in the device).
        • CONTROL pipe is bi-directional
        • Others are uni-directional
  • USB Descriptors
    • Device Descriptors
        • Contains the VID/PID/DID/Serial Number
    • Configuration Descriptors
    • Interface Descriptors
    • Endpoint Descriptors
    • String Descriptors
    • Device Qualifier Descriptors (USB 2.0)
    • Other Speed Configuration Descriptors (USB 2.0)
    • USB “Classes” can add other class specific Descriptors
  • The USB Onion OS Interface Requests Transfers Packets Signaling
  • Signaling
  • USB Signaling
    • USB utilizes differential signaling on the D+ and D- lines.
    • Data is encoded in “non-return to zero with bit stuffing”
        • Bit stuffing is used to ensure enough transitions for the clock recovery circuitry.
    • Most designs use silicon that incorporates an integral Serial Interface Engine (SIE) so you don’t have to worry about the decoding yourself.
    • PCB layout of D= and D- requires care (especially on High Speed devices).
  • The SIE (Serial Interface Engine) Serial Interface Engine (SIE) D+ Bytes USB Transceiver D+
  • Packets
  • USB Packets
      • USB data travels in packets
      • Identified by “Packet ID” (PID)
      • Token packet tells what’s coming
      • Data packets deliver bytes
      • Handshake packets report success or otherwise
  • Packet IDs (PIDS)
    • Token Packets
        • IN, OUT, SOF, SETUP
    • Data Packets
        • DATA0, DATA1 (USB LS/FS)
        • DATA2, MDATA (USB HS)
    • Handshake Packets
        • ACK, NAK, STALL (USB LS/FS)
        • NYET (USB HS)
  • Handshaking Packets
    • Used to ensure correct data delivery on Control, Bulk and Interrupt Transfers
    • ACK – Received with out Error
    • NAK – Device Busy, has no data
    • Stall – Unsupported Request, Request Failed
    • No Response – Request not received or corrupt, will be retried up to 3 times.
  • Packets: Identified by PIDS
  • Three Packet Types
  • Transfers
  • USB Transfer Types
      • Bulk
        • Guaranteed accuracy, but delivery time is variable
        • Best for “bursty” data
      • Isochronous
        • Guaranteed delivery time, but accuracy is not guaranteed
      • Control
        • Enumeration and device control
      • Interrupt
        • Predictable polling time
  • USB Transfers
      • USB Transfers Occur in 1ms Frames (USB 2.0 adds 125 uS Microframes)
      • Host sends “SOF” (Start Of Frame) token every 1ms
      • Host schedules packets inside frames.
  • Anatomy of a USB Frame
      • 12MHz = 1.5MB/s or 1500 bytes/ms
      • Isochronous/Interrupt traffic have guaranteed bandwidth
      • Control traffic is “best-effort”
      • Bulk uses what is left
      • Actual scheduling order depends on host controller
        • UHCI, OHCI
    Video Audio Mouse Control Printer Printer 1 msec frame SOF ... Isochronous Interrupt Control Bulk SOF
  • Packet Sizes Control Bulk Interrupt Isochronous 8, 16, 32, 64 8, 16, 32, 64 1–64 1023 64 512 1024 1024 USB 1.1 USB 2.0 Transfer Type Packet Size
  • Bulk IN Transfer (a) I N A D D R E N D P C R C 5 Token Packet D A T A 1 Payload Data C R C 1 6 Data Packet A C K H/S Pkt I N A D D R E N D P C R C 5 Token Packet D A T A 0 Payload Data C R C 1 6 Data Packet A C K H/S Pkt H D H H H D good—note the data toggle good
  • Bulk IN Transfer (b) I N A D D R E N D P C R C 5 Token Packet N A K H/S Pkt I N A D D R E N D P C R C 5 Token Packet D A T A 1 Payload Data C R C 1 6 Data Packet A C K H/S Pkt H D H H D I N A D D R E N D P C R C 5 Token Packet D A T A 0 Payload Data C R C 1 6 Data Packet A C K H/S Pkt H D H good good not ready
  • Bulk IN Transfer (c) I N A D D R E N D P C R C 5 Token Packet D A T A 1 Payload Data C R C 1 6 Data Packet H (H) D I N A D D R E N D P C R C 5 Token Packet D A T A 1 Payload Data C R C 1 6 Data Packet A C K H/S Pkt H H D good—note same data and data toggle host sees error; no response
  • Bulk IN Transfer (d) I N A D D R E N D P C R C 5 Token Packet S T A L L H/S Pkt H D I N A D D R E N D P C R C 5 Token Packet H (D) device has a problem device detects token error or does not respond
  • Bulk OUT Transfer (a) O U T A D D R E N D P C R C 5 Token Packet D A T A 0 Payload Data C R C 1 6 Data Packet A C K H/S Pkt O U T A D D R E N D P C R C 5 Token Packet D A T A 1 Payload Data C R C 1 6 Data Packet A C K H/S Pkt H H D H D H good—note the data toggle good
  • Bulk OUT Transfer (b) O U T A D D R E N D P C R C 5 Token Packet D A T A 1 Payload Data C R C 1 6 Data Packet A C K H/S Pkt H D H O U T A D D R E N D P C R C 5 Token Packet D A T A 0 Payload Data C R C 1 6 Data Packet A C K H/S Pkt H H D good good O U T A D D R E N D P C R C 5 Token Packet D A T A 0 Payload Data C R C 1 6 Data Packet N A K H/S Pkt H H D device not ready for data host sends data anyway
  • Bulk OUT Transfer (c) O U T A D D R E N D P C R C 5 Token Packet D A T A 1 Payload Data C R C 1 6 Data Packet H (D) H O U T A D D R E N D P C R C 5 Token Packet D A T A 1 Payload Data C R C 1 6 Data Packet A C K H/S Pkt H D H good device sees error; no response
  • Bulk OUT Transfer (d) O U T A D D R E N D P C R C 5 Token Packet S T A L L H/S Pkt H D O U T A D D R E N D P C R C 5 Token Packet H (D) device has problem device detects token error D A T A 1 Payload Data C R C 1 6 Data Packet H D A T A 1 Payload Data C R C 1 6 Data Packet H
  • Control Transfer I N A D D R E N D P C R C 5 Token Packet D A T A 1 Payload Data C R C 1 6 Data Packet A C K H/S Pkt D A T A 0 8 bytes Setup Data C R C 1 6 Data Packet A C K H/S Pkt S E T U P A D D R E N D P C R C 5 Token Packet H H D D A T A 1 O U T A D D R E N D P C R C 5 Token Packet C R C 1 6 Data Pkt N A K H/S Pkt H H D H D H D A T A 1 O U T A D D R E N D P C R C 5 Token Packet C R C 1 6 Data Pkt A C K H/S Pkt H H D Control operation not completed Control operation completed SETUP DATA HANDSHAKE
  • Interrupt IN & OUT I N A D D R E N D P C R C 5 Token Packet D A T A 1 Payload Data C R C 1 6 Data Packet A C K H/S Pkt I N A D D R E N D P C R C 5 Token Packet D A T A 0 Payload Data C R C 1 6 Data Packet A C K H/S Pkt H D H H H D good—note the data toggle good O U T A D D R E N D P C R C 5 Token Packet D A T A 0 Payload Data C R C 1 6 Data Packet A C K H/S Pkt O U T A D D R E N D P C R C 5 Token Packet D A T A 1 Payload Data C R C 1 6 Data Packet A C K H/S Pkt H H D H D H good—note the data toggle good Interrupt transfers are indistinguishable from BULK transfers. They occur at most once per frame.
  • Isochronous Transfer I N A D D R E N D P C R C 5 Token Packet D A T A 0 Payload Data C R C 1 6 Data Packet O U T A D D R E N D P C R C 5 Token Packet D A T A 0 Payload Data C R C 1 6 Data Packet Note: Always DATA0 PID, no ACK H D H H
  • Requests
  • Standard USB Requests
    • Get Status
    • Set Address
    • Get Descriptor
    • Set Descriptor
    • Get Configuration
    • Set Configuration
    • Get Interface
    • Set Interface
    • Set Feature
    • Clear Feature
    • Sync Frame
  • Class Specific Requests
    • Specific to a given class, see the class specification for details.
    • Examples:
      • The Human Interface Device (HID) Class adds “Get Report and “Set Report” requests
      • The Hub Class adds a “Get Port Status” request
  • Enumeration
    • The user plugs the device into a USB port.
    • The hub detects the device.
    • The host learns of the devices presence from the hub (Get Port Status Request)
    • The hub detects whether a device is Low speed or Full Speed.
    • The hub resets the device.
    • The host learns if a full speed device supports high speed.
    • The hub establishes a signal path between the device and the bus.
    • The host sends a Get Descriptor Request to learn the maximum packet size of the default pipe.
    • The host assigns an address (Set Address Request).
    • The host learn about a devices abilities (Get Descriptor Request).
    • The host assigns and loads a device driver.
    • The host’s device driver selects a configuration (Set Configuration Request).
  • Operating System Interface
  • Host Controller Driver
    • Fundamental component of Operating System support for USB
    • USB host controllers are PCI devices
    • What Does it Do?
      • Handles USB peripheral enumeration
      • Provides USB services for higher level drivers. All access to USB peripherals is via these services
  • Which OS’s support USB
    • Pretty much all of them…More and more every day
      • Windows
      • MacOS
      • Linux
      • Solaris
      • VxWorks
  • Windows 95 OSR2.1
    • Microsoft’s first attempt to support USB
    • Only available to OEMs
    • Full of bugs
    • No HID support
    • Avoid it!
  • Windows 98/98SE
    • First Microsoft OS with full USB support
    • Class drivers for HID and USB speakers
    • 98SE fixed a few minor bugs, enhanced performance, added class drivers for USB modems
  • Windows Me (Millennium)
    • Windows 98 was supposed to be the last OS in the Win9x family, but...
    • Follow on to Windows 98
    • Adds performance tweaks, bug fixes, USB audio without clicks and pops, USB Mass Storage class driver
  • Windows NT 4
    • NO SUPPORT FOR USB PROVIDED BY Microsoft!!!!
    • 3rd party NT 4 USB drivers are available
  • Windows 2000
    • Robust USB Support including USB 2.0 High Speed
    • Shares common driver model (WDM) with Windows 98
  • Windows XP
    • Microsoft’s unified home/business operating system
    • Based on Windows 2000
    • Same basic USB support as Windows 2000 with some changes under the hood
    • Supports USB 2.0 High Speed
  • USB Peripheral Drivers
    • Class Drivers
      • Generic driver that supports a certain class of device
      • Human Interface Devices (HID), USB hubs, speakers, mass storage, modems
      • Note: Not all USB Classes that are defined by the USB-IF are implemented!!! Check your target OS for support. (i.e. I know of no OS that has implemented the Firmware Update Class)
    • Custom Drivers
      • Operating Systems often include vendor specific drivers that have passed certification (e.g. WHQL)
  • HID Class
      • Built into Windows 98 (or later)
      • No need to write (or install) a driver!
      • Used by mice and keyboards, but can be used for custom devices also.
      • Communicates with devices using reports
        • Set Report, Get Report
      • Full Spec at http://www.usb.org
        • You need the spec, and the HID Usage Tables
  • Custom Device Driver Options
    • Look for an Open Source Device Driver
        • http://libusb-win32.sourceforge.net (Windows)
        • http://libusb.sourceforge.net (Linux and others)
    • Use a “General Purpose” Device Driver
    • Write a “Proprietary Custom Device” Driver (or have it written for you by a consultant)
  • Generic USB Device Drivers (for Windows OS’s)
    • Check your silicon manufacturer, they may have a general purpose driver you can use with their silicon (Cypress and FTDI both do)
    • Thesycon USBIO (http://www.thesycon.de)
    • MCCI Virtual COM port driver (http://www.mcci.com)
    • Jungo (http://www.jungo.com)
  • Writing a Device Driver
    • Requires Specialized Knowledge (WDM and USBDI, Kernel Debuggers, etc.)
    • Long Learning Curve (i.e. >6months)
    • Not very well documented
    • Avoid this if you can!!!
  • Certifications and Logo’s
    • USB Implementers Forum Certification
      • Needed to use the new “USB Certified” Logos
        • Join the USB-IF or become a non-member Logo Licensee
        • Attend a “Plug-Fest” or have your device tested for compliance by an independent lab
    • Windows Hardware Quality Labs (WHQL) Certification
        • Download the HCT and run the applicable tests (if a self test is permitted for your device) or have your device tested for compliance by an independent lab
  • Some Considerations for DSP Applications
  • USB Silicon Options
    • USB Transceiver Only
        • Cypress TX2, Phillips, etc.
        • These are primarily intended for FPGA’s that implement a Serial Interface Engine (SIE)
    • USB Transciever + SIE
        • Cypress SX2, Phillips, etc.
        • This would be a good option for DSP’s without USB support
    • USB Transciever + SIE + Microprocessor
        • Cypress EZ-USB, EZ-USB FX, EZ-USB-FX2, Microchip USB PIC, DSP’s that have USB Support
        • This would also be a good option for DSP’s without USB support
    • Fixed Function Devices
        • FTDI USB to Serial Converter Chips (This is a good option for DSP’s)
        • USB to ATAPI Bridge Chips
  • USB Transfer Types
    • Since some applications for Digital Signal Processing are “Stream” operations you might think that “Isochronous” transfers are the most appropriate type to use. Sometimes, but not always…Consider using RAM buffers and a Bulk or Interrupt Transfer Type.
    • In lower bandwidth applications, consider the FTDI USB to Serial Converter, they are a good shortcut if you can use them.
  • USB Resources
  • USB Resources: Books
      • Devices
        • Jan Axelson, USB Complete, Second Edition
        • John Hyde, USB Design By Example , Second Edition
      • Windows Drivers (including USB)
        • Walter Oney, Programming the Microsoft Windows Driver Model
        • Chris Cant, Writing Windows WDM Device Drivers
  • USB Resources: Internet
      • www.usb.org
        • USB Specifications and Class Specifications
        • Draft docs
        • Bulletin board (Developer Forum)
        • Product information incl. chips
  • USB Resources: Consultants
    • J. Gordon Electronic Design
    • (763) 786-2405
    • http://www.jged.com
    • (A shameless plug for my employer)
  • Questions
    • ?
  • Optional Topics (if there is time)
    • Optical Isolation and USB
    • USB Tools
    • USB Serial Numbers and Windows XP
    • A special thanks to Cypress Semiconductor for allowing use some of the included slides.