Microsoft And Device Bay Dan Shapiro Program Manager Microsoft Corporation

1
Microsoft And Device BayDan ShapiroProgram
ManagerMicrosoft Corporation
2
Getting Started With Device Bay

• Grant Ley, TI, Chuck Stancil, Compaq, and
  Krunali Patel, TI
• USB Device Bay Controller Requirements
• Jeff Wolford, Compaq
• Building the First Device Bay Platforms and
  Devices

3
USB Device Bay ControllerImplementation,
Software, And Power ConsiderationsGrant Ley,
Texas InstrumentsChuck Stancil, Compaq Krunali
Patel, Texas Instruments
4
The Device Bay Concept
Expansion/remote bay system
Desktop system
Bay
Mobile system
Device
USB data path
1394 data path
Bay management
Power
5
Device Bay Specification

• Open industry specification jointly developed by
  Compaq, Intel, and Microsoft
• www.device-bay.org
• Private questions devicebay_at_acmenet.com
• Public send subscribe device_bay to
  majordomo_at_europa.com
• Supports a wide variety of devices
• Mass storage (HDD, DVD/CD-ROM, tape, etc.)
• Communications and connectivity (modem, LAN)
• Audio and security via USB

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Device Bay Controller

• For specification of the DBC, see Section 6 of
  the Device Bay Spec
• DBC manages all bays
• Maintains bay status
• Detects device insertion/removal
• Enables Vid (enumeration power) to the device
• Detects user removal requests via optional bay
  mounted push button

7
Device Bay Connector Signals

• Presence detect
• USBPRSN, 1394PRSN
• Pulled to ground to indicate interface type (USB
  or 1394 or both)
• USB data signals
• 1394 data signals

8
DBC Signals To The Bay

• Required
• Lock enable
• ID power (Vid) enable
• Optional
• Removal request
• Security lock status
• Bay status indicator

9
ACPI DBC Implementation
PCI
ACPI
USB root controller
1394 link controller
PHY/Link interface
Device Bay controller
Walk-up port
1394 PHY
Device Bay 0
Device Bay 1
Device Bay 2
Device Bay 3
10
ACPI DBC Implementation

• ACPI name space and control methods describe
  the DBC implementation
• Can reside on a bus like PCI, I2C, SMBus
• No physical connection between DBC and PHY
• DBC data structures implemented as a register set

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USB DBC Implementation

• DBC implemented as a USB function
• Connected to the USB hub
• Can be integrated into the hub as an embedded
  function
• Must have simple Link controller to
  communicate with a 1394 PHY
• Walk-up ports can be connected to the same USB
  hub or 1394 PHY that is connected to the bays

12
USB DBC Implementation

• DBC is a self-powered or bus-powered USB device
• DBC communicates with system via USB control and
  interrupt endpoints (pipes)
• DBC descriptors contain info about
• Bay control
• Bay status
• DBC capabilities
• DBC descriptors accessed using USB DBC
  class-specific requests

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USB DBC Implementation
PCI
USB root controller
1394 link controller
1394 PHY
Device Bay controller
PHY/Link interface
Walk-up port
USB hub controller
1394 PHY
Device Bay 0
Device Bay 1
Device Bay 2
Device Bay 3
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USB-Based DBC System
Device Bay standard
Mech Form Factor(s)
Interface signals USB Data 1394 Data Bay
Management Power
Management commands and procedures
Communications methods USB Class Device
Connector
Computer system
Bay
USB HUB
USB Host Ctrl
Device
System Bus
Bay Controller
Mgmt. S/W
CPU
Phy/Link I/F
Bay
1394 Host Ctrl
1394 PHY
1394 PHY
Device
Phy/Link I/F
Power supply

• Riser card in desktop chassis
• Remote expansion chassis
• Monitor with Device Bay capability
• Docking Station for mobile platforms

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Remote Considerations

• Bus or hybrid powered USB hub
• Minimum of two 1394 walk-up ports
• Three recommended to support spanning
• Supply 1394 bus power
• Recommend minimum of 15W at 20V
• Support DB32 devices
• Requires 12V support

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Remote Device Bay System
Host PC
Remote Device Bay
Power Supply
1394 OHCI
Windows
1394 Walkup Port 0
Remote DBC
1394 Walkup Port 1
USB OHCI/UHCI
DBC Class Driver
USB Walkup Port 0
USB Walkup Port 1
Monitor
Bay 1
Bay 0
Software stack 1394 Bus Driver OHCI Port
Driver SBP2 Port Driver USB Bus Driver USB
OHCI Port Driver USB Audio Class Driver USB
DBC Class Driver
HDD
DVD
USB Speaker
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The Software Pieces

• Universal Serial Bus Driver (USBD)
• USB OHCI/UHCI port driver
• 1394 bus driver
• 1394 OHCI port driver

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The DBC Link Controller

• Supports a 400 Mbps PHY/link interface
• Strongly recommend P1394a compliance
• Software access to PHY registers compliant with
  method defined by 1394 OHCI Release 1.0
• Asynchronous transaction capable
• Minimal CSR and Config ROM space
• General ROM format required

19
The DBC Link Controller

• Isochronous resource manager, cycle master, and
  bus manager capability not required
• Maximum payload size is 1 quadlet

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USB DBC Class Specification

• Defines the USB communication channel used by the
  DBC to communicate with the host
• Standard device descriptor
• Standard configuration descriptor
• Standard endpoint descriptors
• Control
• Interrupt
• USB port power management

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USB DBC Class Specification

• Device descriptors
• Class-specific device descriptors
• Subsystem descriptor
• Bay descriptors
• Standard device descriptor

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USB DBC Class Specification

• USB requests
• Standard requests
• Class-specific requests
• GetBayStatus
• Get/SetPHYCommunicationRegister
• Optional vendor-specific requests
• For example, asset tracking
• Set/ClearFeature requests
• See www.microsoft.com/hwdev for white paper about
  USB DBC Spec

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Design Considerations

• Bay state machine
• The LOCK_CTL and PWR_CTL relationship
• Initializing read-only fields
• Driving the bay status indicator

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Bay State Machine Design

• Behavior after reset with a device
  present
• The state transition Bay Empty ? Device Inserted
  (or any other state) requires software
  intervention
• DEVSTSCHG can either be set or cleared if set
  system BIOS should clear it!

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Bay State Machine Design

• Software state transitions
• All software state transition requests (via
  BAY_STREQ field in BCERx) must be qualified with
  device presence by the hardware!
• Software state transitions occur at the time of
  the write to the BAY_STREQ field (i.e., there is
  no queuing!) however, DBC hardware will always
  retain the last non-zero value written to
  BAY_STREQ

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LOCK_CTL And PWR_CTL Relationship

• Normal sequence of these two bits
• 1. After device is inserted S/W sets LOCK_CTL
• 2. S/W sets PWR_CTL
• 3. When device is to be removed S/W clears
  PWR_CTL
• 4. S/W clears LOCK_CTL
• DBC hardware MUST prevent PWR_CTL (VID enable)
  from being set if LOCK_CTL is not set

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LOCK_CTL And PWR_CTL Relationship

• If both bits are set and LOCK_CTL is erroneously
  cleared first (by S/W) then DBC hardware must
  automatically clear PWR_CTL
• If the software controlled interlock mechanism is
  overridden then DBC hardware must clear PWR_CTL

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Initializing Read-Only Fields

• There are fields in the DBC (registers or
  descriptors) that contain static information
  about a DB subsystem they could be implemented
  as write-once and initialized via
• An embedded controller
• OEM BIOS
• A configuration EEPROM

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Driving The Bay Status Indicator

• Use of bipolar drivers allows the system designer
  to use a two-pin bipolar (green/yellow) LED, a
  three-pin LED or discrete LEDs

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Driving The Bay Status Indicator

• If using bipolar drivers with a 2-pin bipolar LED
  watch your supply voltage!
• 3.3V probably isnt high enough!
• VOH(min) - VOL(max) VF(LED) VR
• typical case VOH(min) ? VCC - 1.0V
• VOL(max) ? 0.4V
• VF(LED) ? 2.1V
• ? 2.3V - 0.4V 2.1V VR

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Driving The Bay Status Indicator

• Dont power the LEDs from an auxiliary or standby
  power supply! The LEDs must be off when the
  system is in S3 through S5!

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Call To Action

• Use Device Bay resources
• Spec is at www.device-bay.org
• Private questions devicebay_at_acmenet.com
• Public send subscribe device_bay to
  majordomo_at_europa.com
• USB DBC Spec. white paper on www.microsoft.com/hwd
  ev
• OEMs and DBC silicon providers start working
  together
• Send your hardware to Microsoft for software
  development and testing

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Device Bay, Beyond The SpecificationJeff
WolfordSenior Systems ArchitectAdvanced
Technology GroupCompaq Computer Corporation
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Device Bay Introduction

• Open industry specification jointly developed by
  Compaq, Intel, and Microsoft
• www.device-bay.org
• Private questions devicebay_at_acmenet.com
• Public send subscribe device_bay to
  majordomo_at_europa.com
• Supports a wide variety of devices
• Mass storage (HDD, DVD/CD-ROM, tape, etc.)
• Communications and connectivity (modem, LAN)
• Audio and security via USB

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Device Bay Overview

• Complete architecture for adding/upgrading PC
  peripherals without opening the chassis
• Specifies bus interfaces, form factor,
  mechanicals, and OS behavior for device insertion
  and removal
• Mandatory buses
• Host USB, 1394 (400 Mbit host ports) and POWER
  Bus(es) Vid, Vop
• Device either USB, 1394 or both at least Vid
  and Vop if gt 1.5 Watt

• Key enablers
• USB
• IEEE 1394

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Device Bay OverviewForm-factors

• 3 Device Bay form-factors
• DB32 - 32.00 x 146.00 x 178.00 mm
• Size and power optimized for desktop
• DB20 - 20.00 x 130.00 x 141.50 mm
• DB13 - 13.00 x 130.00 x 141.50 mm
• DB20 and DB13s size and power optimized for, but
  not limited to, notebook implementations

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Device Bay OverviewRetaining a connection

• Retention feature
• Required to engage immediately
• Software-controlled interlock
• Required
• Security lock
• Optional
• Any of the above can be combined

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Device Bay Overview Buses

• Vid power 1.5W at 3.3V (switched by the
  system)
• Vop power (switched by the device)
• DB32 - 30W electrical, 25W thermal
• DB20 and DB13 - 4W
• 2 serial buses (1394 and USB)
• Keeps appropriate performing devices on the
  corresponding bus
• Allows power consumption to scale with
  performance of the device

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Device Bay Overview USB

• USB is a medium-bandwidth bus (1.2 - 12
  Mbps)
• Bay requirements
• One USB port per bay
• Device Bay device requirements
• Provide power requirement registers
• Unique serial number
• If Vop is used, must be switched with
  configuration complete command

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Device Bay Overview 1394

• IEEE 1394 and future extensions
• Initial transfer rate is 100 - 400 Mb/s, with
  P1394A and P1394B extensions to support Gbps data
  rates that must be backward compatible
• Device Bay bay requirements
• One 1394 port per bay
• Must support 400Mbps minimum

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Device Bay Overview 1394

• Device Bay device requirements
• Provide power requirement registers
• If Vop is used, must be switched with start/stop
  unit command
• Devices can use 100 - 400Mbps
• Encouraged to use highest rate possible for
  devices to minimize equivalent bandwidth
  requirements

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Device Bay Overview Connector

• Open industry standard
• Blind-mate connector pair
• Plug in the device, receptacle in the bay
• Supports power, one USB port, and one 1394 port
  in one connector
• Pin configuration for higher speed 1394 (gt 1Gb/s)
  and hot-plug
• High durability (min 2,500 cycles)
• Flexible and cable friendly

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Device Bay Overview Device Bay Controller (DBC)

• Two possible implementations
• USB
• ACPI - abstracts HW I/F (PCI, I2C, etc.)
• Required functions
• Power control
• Insertion events (PRSN)
• Software-controlled interlock mechanism
• 1394 PHY port mapping
• USB port mapping

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Device Bay DevelopmentImplementers guide

• Bay mechanical design
• Bay electrical design
• Device Bay Controller (DBC) software
  requirements
• Device mechanical design
• Device electrical design
• Power
• Signal
• Reset

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Bay Mechanical DesignBay cover

• A bay must be covered when no device is present
  to keep from short circuiting the air flow from
  other bays
• Watch out for
• Devices that are hollow in the center
• Hanging up on devices retention features
• Interacting with the ESD/EMI bay spring

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Bay Mechanical DesignDevice alignment

• Bay must provide rough device alignment
• Needs to get the device to a /-2mm connector
  tolerance
• Needs to keep the device in tight vertical and
  horizontal tolerance
• Allows retention and interlock features to engage
  and disengage properly

47
Bay Mechanical DesignRetention mechanism

• Needs to hold the device on the connector and not
  allow the device to back off (i.e., 1.46 mm
  minimum wipe)
• Design for multiple device enclosure
  materials
• Steel, aluminum, plastic, and bi-material (metal
  over plastic) that produces two materials on the
  same retention face

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Bay Electrical DesignPower switching

• Vid switching
• Should be ramped
• Insertion resistance (FET, wire, etc.)
• Vop switching
• Optional
• Difficult to maintain valid voltages
• Feedback from processor power, not from DB
  power
• Must support switching of maximum power on all
  voltage rails

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Bay Electrical Design Connector sets

• Connector stack-up
• Two sets minimum for cable version
• Easy to get three sets
• Watch termination and differential routing
  through noisy digital logic
• There may also be one set in the device for
  mechanical isolation or for adapters

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Bay Controller DesignDBC software

• After an insertion notification, the DBC driver
  needs to verify several things before it turns on
  Vid
• Verify the Bay is enabled to take devices
• Verify there is 1.5W in the power budget
• Wait for the device to settle down and become
  fully latched on the connector before enabling
  power

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Device Design MechanicalCritical dimensions

• Most critical is keeping the connector square
• Connector float in the Bay and connector
  blind-mate features will compensate for some
  tolerance in the X, Y, and Z planes
• But, if the connector is not square with the
  device, the float and blind-mate will be of
  little help
• DB32 height is /-0.25mm

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Device Design Mechanical Retention features

• Critical dimension is from the retention edge to
  the back of the device
• Required faces must be present and in tolerance
• Bi-material features must have smooth transition
  from one material to another so as not to snag
  the bays retention mechanism

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Device Design Mechanical Device shell

• Round corners and edges within spec
• Round edges reduces the drag of insertion and
  removal of device
• Round corners help the user get the device lined
  up and in the bay
• Round edges supports new handling models
• The device feels better in the users hands

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Device Design Mechanical Device shell

• Cosmetics no longer limited to front bezel
• Users now see the entire device
• Additional user models beyond upgrade need to be
  considered
• Casual device swapping
• Taking devices on the road

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Device Design Electrical Power switching

• Vop power switching
• di/dt requirements support
• Hot plugging
• Capacitance load-independent
• Supports lower power consuming PC in the future
• Vid - switched by the Bay (1.5W,3.3V)
• Needed to power the native bus interface and
  allow access of identification and power registers

56
Device Design Electrical Power switching

• Vop power switching assumptions
• No more than 5uA can be drawn on Vop if Vid is
  not valid
• When Vid is not valid, Vid is not required to be
  shorted to ground
• Vop may or may not be valid when Vid is disabled
• Vop power rails can be switched on/off in any
  order when Vid is not valid

57
Device Design Power

• 1394 PHYs with Links required as first
  connection
• Provides Link to get device information,
  including driver and power requirements
• Full power authorization via native bus driver
  stack
• USB configuration complete
• 1394 Start Unit command
• Device Bay power manager would fail the above
  commands to block enumeration

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Device Design Power

• All devices are required to support ACPI states
  0, 2, and 3
• Support of state 1 is highly desired to support a
  fully power managed PC
• 0 device is fully on
• 1 reduced power consumption on Vop
• 2 no power consumption on Vop and, if
  possible, reduced power on Vid
• Can be same as pre-enumeration state
• 3 device is fully off

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Device DesignElectrical problems

• Problem using 12V of Vop for switch voltage
  enhancement for V5 and V33
• Vid is not valid, thus the gate might not be
  grounded
• Vop12v is valid, thus the gate might not be
  pulled to 12V

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Device DesignElectrical problems

• Problem using Vid (3.3V) and Vop (5V) to drive
  reset circuits
• Vop is only required to be valid with Vid
• If Vop is used for a reset RC circuit, the reset
  might not be done when Vid becomes valid

61
Device DesignElectrical problems

• Problem input leakage current and voltage for a
  device that is off
• Could violate 5uA current limit
• Voltage feed-through could allow this voltage to
  come out another pin
• Requires fail-safe buffers

62
Device DesignElectrical problems

• Problem tying two resets together
• PHY reset RC was biased to 1.4V because of input
  voltage leak when the device was powered off via
  TPbias
• PHY reset was tied to Link reset, causing the
  Link reset edge to start at 1.4V, causing a
  non-complete edge on its reset

63
Device DesignReset problems

• When the 1394 bus has completed the self-ID
  phase, the Link must be able to respond to CSR
  and ROM reads if it cannot, there are several
  options
• Best be able to respond after self-ID
• Second best respond with an ack-pending and
  respond before the ack-pending times out

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Device DesignReset problems

• Link reads after self-ID
• Third best strap PHY to come up in link-off
  mode
• Then when the Link is able to take commands,
  assert the LPS to the PHY and if the PHY does not
  do a reset on LPS status change, pop a 1394 bus
  reset
• Worst, but better than none let the initial CSR
  reads ack time-out when the Link becomes
  available, cause a 1394 bus reset

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Demo Device Insertion
PRSN -gt DBC, DBC Driver Device Insertion
Start blinking LED DBC Driver -gt DB PWR MGR
Do we have 1.5 W ? DB PWR MGR -gt DBC Driver
YES DBC Driver -gt DBC IF Vop switched, turn
on Vop Turn on Vid Turn LED on solid
Wait for Native Bus to take over NATIVE
BUS Disk.sys -gt SBP-2 Start Unit SBP-2 -gt
PWR Filter PWR Filter -gt DB PWR MGR See Start
Unit DB PWR MGR -gt 1394 Filter Read Unit
Directory Power Reg 1394 Filter -gt DB PWR MGR
Power Requirements Data DB PWR MGR -gt 1394
Filter Pass or Fail Start Unit
Disk.sys
SBP-2
Device Bay power manager
PWR FILTER
1394 class
OHCI
TI LINKS
DBC driver
PCI
USB
ACPI
Device Bay controller
PCI OHCI
1394 PHY
V33
1394
PRSN
V5
Vid
V12
DB connector
DB device
66
Demo Copy Files

• Copy files from Device Bay device to another

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Demo Device Removal
Disk.sys
RemReq -gt DBC Start blinking LED DBC -gt DBC
Driver Device Removal Request DBC Driver -gt
Plug-n-Play MGR Remove Device
Request Plug-n-Play MGR Close down all open
file handles Send the device to D3 state
When complete, send ACK to DBC Driver DBC
Driver -gt DBC Turn off Vid Wait for
device to discharge IF Vop switched, turn off
Vop Turn LED off Release software
interlocks DBC Driver -gt DB PWR MGR Release
allocated power
SBP-2
Plug -n- Play manager
PWR FILTER
1394 class
OHCI
TI LINKS
DBC driver
PCI
USB
ACPI
Device Bay controller
PCI OHCI
RemReq
1394 PHY
V33
1394
PRSN
V5
Vid
V12
DB connector
DB device
68
Demo Moving Devices

• Show movement of a Device Bay device from one
  machine to another

69
Demo Swapping Devices

• Remove one Device Bay device
• Insert a different Device Bay device in the same
  bay

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Questions And Answers