USB Discussion

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USB DiscussionUSB DiscussionUSB Discussion

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USB DiscussionUSB DiscussionUSB Discussion�USB Introduction

�USB Standard Command

�USB Descriptor


USB Introduction

USB USB IntroductionIntroduction

�Preface

�USB Architecture

�USB transfer data format

Elan Microelectronics Corporation

4

USB Preface• USB origin

– 1996 USB 1.0 12/1.5 Mbits• Compaq, Intel, Microsoft, NEC

– 1998 USB 1.1

– 2000 USB 2.0 480Mbits

– 2004 Wireless USB


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USB Preface• Shortcoming of existing PC I/O Paradigm– Interrupts

– I/O Addresses Conflict

– Non-Shareable Interface

– Cable Crazed

– Installation and Configuration of Expansion Cards

– No Hot Attachment of Peripheral

– Cost


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USB Preface


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USB PrefaceClass (群組)• HID Class 人機介面裝置群組人機介面裝置群組人機介面裝置群組人機介面裝置群組

• Keyboard Mouse…..

• Audio Class 聲音裝置群組聲音裝置群組聲音裝置群組聲音裝置群組• USB Mac USB Speaker

• Mass Storage Class 大量儲存裝置群大量儲存裝置群大量儲存裝置群大量儲存裝置群• Flash Disk USB CD-ROM

• Display Class 顯示器裝置群組顯示器裝置群組顯示器裝置群組顯示器裝置群組• USB Monitor

• Communication Class 通訊裝置群組通訊裝置群組通訊裝置群組通訊裝置群組• Phone


USB introduction

USB USB introductionintroduction

�Preface

�USB Architecture

�USB transfer data format


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USB Architecture• USB Peripheral Connection

• Root Hub, Topology

• 127 devices (including root hub)

• Up to 6 tiers (up to 5 meters per segment)


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• USB Connector

– 4 pin connector, 4 wire cable

– 2-wire differential signaling, NRZI Supply

– Sourcing +5V

– Signaling at 3.3V

USB Architecture


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USB Architecture• USB Device Concept

Address

– 7 bits record for 128 address. (0 ~ 127)

– Each USB Device has one Device Address.

– One Host has support max 127 devices.

– Address 0 reserve for initial plug in device.


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USB Architecture• USB Device ConceptEndpoint

– 4 bits record for 16 Endpoints. (0 ~ 15)

– Endpoint 0 reserve for Control Endpoint.

– Direction• IN Device to Host

• OUT Host to Device

– Transfer Type• Control

• Interrupt

• Isochronous

• Bulk


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USB Architecture• Transfer Type

– Control Transfer 控制型傳輸• For All Device

– Interrupt Transfer 中斷型傳輸• Mouse / Keyboard

– Isochronous Transfer 即時型傳輸• Audio / Video

– Bulk Transfer 巨量型傳輸• Printer / Scanner


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USB Architecture

MassYesNonBulk

NormalYesInterrupt

MassNo90%Isochronous

NormalYes10%Control

Data

Amount

Error

Recovery

Bandwidth

Guarantee

Transfer

Type


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• Frame 訊框

USB Architecture

F ram eF ram eF ram eF ram e

�10% for Control Transfer

�MAX 90% for (Isochronous + Interrupt)

�Remain for Bulk Transfer


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USB Architecture

Full / Low Speed Frame Size (1ms)Full / Low Speed Frame Size (1ms)

High Speed MicroHigh Speed Micro--Frames (125us)Frames (125us)

1ms1ms 1ms1ms

Classic USB Frame Ticks Classic USB Frame Ticks Full Speed Isochronous Data PayloadFull Speed Isochronous Data Payload

USB 2.0 MicroUSB 2.0 Micro--Frame TicksFrame Ticks

(1/8(1/8thth Classic Frame) Classic Frame) High Speed Isochronous Data PayloadHigh Speed Isochronous Data Payload

. . . . . .

. . . . . .

• Frame 訊框


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• Frame 訊框

– UHC Host Controller

– OHC Host Controller

USB Architecture

SOF 即時傳輸中斷型控制型巨量型

1ms

SOF 非週期性週期性(isochronous; bulk) 非週

期性

1ms


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USB Architecture

• USB 1.1– Low Speed : 1.5Mb/s

– Full Speed : 12Mb/s

• USB 2.0– Low Speed : 1.5Mb/s

– Full Speed : 12Mb/s

– High Speed : 480Mb/s


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USB Architecture• USB Bus speed model


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USB Architecture• Low/Full-speed Identification


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USB Architecture• High-speed Identification

– The hub drives SE0 to device

– The device creates a Chirp K

– The hub sends an alternating sequence of Chirp K’s and Chirp J’s

– The hub asserts SE0, then to the high-speed Enable state

– The device disconnects the D+ pull-up resistor, enter the high-speed Default state


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USB Architecture• The elements

– USB Hardware• USB Host Controller/Root Hub

– UHCI– OHCI– Enhanced Host Controller Interface

• USB Hub• USB Device

– USB Software• USB Device Driver• USB Driver• Host Controller Driver


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USB Architecture

End PointElectrical ,

mechanical,

signal transaction

Include 1.USBD

2. HCD


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ClientClient

SoftwareSoftware

InterfaceInterface

EndpointsEndpoints

Data FlowsData Flows

BuffersBuffers

USB DeviceUSB Device

HostHost

PipesPipes

USB Architecture

• Endpoint


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USB Architecture

• How Device Present Themselves to SW• Device Descriptor 裝置描述元

• Configuration Descriptor 設定描述元

• Interface Descriptor 界面描述元

• Endpoint Descriptor 終點描述元

• String Descriptor 字串描述元

• Class specific Descriptor 群組特定描述元


USB introduction

USB USB introductionintroduction

�Preface

�USB Architecture

�USB Transfer Data Format


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USB transfer data formatToken Packet

Data Packet

Handshake Packet

Setup stage

Data stage

Status stage


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USB transfer flow• Control transfer


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USB transfer flow• Bulk transfer


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USB transfer flow• Interrupt transfer


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USB transfer flow• Isochronous transfer


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Token Packet Format

• Packets– The basic building blocks of USB transaction

Data length

– SYNC:8bit

– PID:4bit (and 4bits check field)

– Data: Depend on transfer type

– CRC: 5bit or 16bit

– EOP:3 bits time

SYNC PID DATA CRC EOP


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Packet Identifier Type– PID:

• Token Packet– SOF

» PID [3:0] 0101» Start of frame

– In » PID[3:0] 1001» Transfer direction , device to host

– Out » PID [3:0] 0001» Transfer direction, host to device

– Setup » PID [3:0] 1101» A control transfer start

• Data Packet- For data toggle – Data0– Data1– Data2(USB 2.0)– MData(USB 2.0)


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Packet Identifier Type– PID:

• Handshake Packet – Acknowledge (ACK)– No Acknowledge (NAK)– STALL– NYET(USB 2.0)

» in response to a CSPLIT or PING• Special Packet

– Preamble Packet» For Low Speed device communication» Without EOP

– ERR(USB 2.0)» Split Transaction Error Handshake

– SPLIT(USB 2.0)» Using at high-speed hub with Full/Low speed device

– PING(USB 2.0)» High-speed flow control probe for a bulk/control endpoint


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Other Token packets– Start-/Complete-Split Transaction Token

• SC : 0=Start , 1=Complete

• S : for Control/Interrupt– 0=Full speed , 1=Low speed

• ET : Endpoint type


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PID for data packet– Isochronous IN High bandwidth Endpoints

– Isochronous OUT High bandwidth Endpoints


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USB Transaction• Transaction

– Setup Transaction• Two-Stage Control Transfer

– Setup stage, Status stage

– EX: Remote weak up

• Three-Stage Control Transfer – Setup stage/ Data stage/ Status stage

Setup IN IN IN IN OUT

Setup Stage Data Stage Status Stage


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– IN Transactions

USB Transaction

Host�� Device

Token stage

Host �� Device

Handshake

Device�� Host

Data stage

SYNC IN TOKEN EOP

SYNC Data (MAX 64byte) EOP

SYNC ACK EOP

NOTE: “Isochronous In” transaction maximum data

packet1024 bytes (USB 1.1) and without handshake stage


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– OUT Transactions

USB Transaction

Host�� Device

Token stage

Device�� Host

Handshake

Host �� Device

Data stage

SYNC OUT TOKEN EOP

SYNC Data (MAX 64byte) EOP

SYNC ACK EOP

NOTE: “Isochronous OUT” transaction maximum data

packet1024 bytes (USB 1.1) and without handshake stage


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– Split Transactions (USB 2.0)• Start-split

USB Transaction

• Complete-split


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USB Architecture• USB Bus speed model


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– Split Transactions• High-speed Split IN transaction

USB Transaction


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– Split Transactions• High-speed Split OUT transaction

USB Transaction


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Bus EnumerationFive bus states during the USB device plug in:– Attached

• Device plug in/out USB port

– Powered state• Disable port >100ms (for stable)

– Defaule state• Reset signal 10ms• Draw no more than 100mA from Vbus

– Address state• Assign a new address

– Configured state


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Device state


USB Standard Command

USB Standard USB Standard CommandCommand


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• Command Length: 8 Bytes

0706050403020100

Request wValue wIndex wLengthType


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Example: • Get Status8a 00 0000 XX00 0200a =0x00: DEVICEa=0x01 : INTERFACEa=0x02 : ENDPOINT


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• Reply “ Get Status”For DEVICE

For ENDPOINT


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• Set Address00 05 XX 00 00 00 00 00

XX : Address number


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USB Standard Command• Get Descriptor

80 06 00 0X 00 00 L1 L2

0X : Descriptor Type

L1,L2 Descriptor Length


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USB 2.0


USB Descriptor

USB USB DescriptorDescriptor


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Device Descriptor Definition

SubClass1bDeviceSubClass5

ValueSizeFieldOffset

Number1bMaxPacketSize07

Protocol1bDeviceProtocol6

Class1bDeviceClass4

BCD2bcdUSB2

Constant1bDescriptorType1

Number1bLength0


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Device Descriptor Definition

ID1idVendor8

ID1idProduct10

Number1bNumConfigurations17

Index1iSerialNumber16

Index2iProduct15

Index1iManufacturer14

BCD1bcdDevice12



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Device Descriptor


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Device_Qualifier descriptor

Protocol1bDeviceProtocol6

Number1bMaxPacketSize07

SubClass1bDeviceSubClass5


Zero1bReserved7

Number1bNumConfigurations6

Class1bDeviceClass4

BCD2bcdUSB2


Number1bLength0


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Configuration Descriptor

Bitmap1bmAttributes7

Number1bConfigurationValue5


mA1bMaxPower8

Index1iConfiguration6

Number1bNumInterfaces4

Number2wTotalLength2


Number1bLength0


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Other_Speed Configuration


Number1bConfigurationValue5


mA1bMaxPower8

Index1iConfiguration6

Number1bNumInterfaces4

Number2wTotalLength2


Number1bLength0


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Interface Descriptor

Protocol1bInterfaceProtocol7

SubClass1bInterfaceSubClass6

Number1bNumEndpoints4


Index1iInterface8

Class1bInterfaceClass5

Number1bAlternateSetting3

Number1bInterfaceNumber2


Number1bLength0


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Interface Descriptor


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Endpoint Descriptor

Number2wMaxPacketSize4


Number1bInterval6


Endpoint1bEndpointAddress2


Number1bLength0


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Endpoint Descriptor• bmAttributes

– Bits1..0 : Transfer Type• 00 = Control• 01 = Isochronous• 10 = Bulk• 11 = Interrupt

– Bits3..2 : Synchronization (for ISO)• 00 = No Synchronization• 01 = Asynchronous (Free running)• 10 = Adaptive (locked to SOF)• 11 = Synchronization (locked to sink)

– Bits5..4 : Usage Type (for ISO)• 00 = Data endpoint• 01 = Feedback endpoint• 10 = Implicit feedback Data endpoint (group)• 11 = Reserved


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Endpoint Descriptor• wMaxPacketSize

– Bits10..0 : Maximum packet size– Bits12..11 : Additional transaction per microframe

• 00 = None(1 transaction per microframe)• 01 = 1 additional (2 per microframe)• 10 = 2 additional (3 per microframe)• 11 = Reserved

– Bits15..13 : Reserved and must be set to zero

• bInterval : interval for polling endpoint– Full-/High-speed ISO : 1~2^15– Full-/Low-speed INT : 1~255 – High-speed INT : 1~2^15


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Endpoint Descriptor


THE ENDTHE ENDTHE END

Technology

USB Discussion