USB Under the Hood

8/8/2019 USB Under the Hood

1/33

Colin [email protected]

USB Under the Hood
mailto:[email protected]:[email protected]


2/33

Mentor Graphics Confidential Information

USB is a Good Thing

U

S

B

2


3/33


What is USB?

nAlternative to old-fashioned serial and parallel

interfacesnMinimises number of PC connectors

nSimplifies I/O and offers true plug-n-play

nSupports up to 127 devices

nMultiple data rates

USB 1.1: full speed [12Mb/s] and low speed [1.5Mb/s]

USB 2.0: high speed [480Mb/s]

USB 3.0: very high speed [4.8Gb/s]

3


4/33


USB Technology Overview

nThree types of USB device

Host

Peripheral

On-The-Go (OTG)

Std-A

Std-A

Std-A

Hub

Std-B

Mini-B

4


5/33


Typical Peripheral Applications

5

Low Speed

(LS)

Mice

KeyboardsJoysticksGamepads

Full Speed

(FS)

Modems

Digital CamerasPrintersScanners

Microphones

Mass Storage

BroadbandHome NetworkingResidential GatewaysDigital Video/Audio

Hi-Speed

(HS)


6/33


USB Topology

6

Hub4

Peripheral Peripheral Peripheral

PeripheralPeripheralHub

3

Hub2

PeripheralPeripheral

Hub1

Host

Root Hub


7/33


USB Topology

7

Hub4



3

Hub2


Hub1

HostRoot Hub


8/33


USB Topology

8

Hub4



3

Hub2


Hub1

Host

Root Hub


9/33


USB Topology

9

Hub4



3

Hub2


Hub1

Host

Root Hub


10/33


USB Topology

10

Hub4



3

Hub2


Hub1

Host

Root Hub


11/33


USB Topology

11

Hub4

Function Function Function

FunctionFunctionHub

3

Hub2

FunctionFunction

Hub1

Host

Root Hub


12/33


USB Communications

12

USB

Interface

Endpoint 0

Endpoint 1

Endpoint 15

CPU

Input/Output Device

USB Peripheral Controller

To

hostor hub


13/33


USB Communications

13

USB

Interface

Endpoint 0

Endpoint 1

Endpoint 15

CPU

Input/Output Device

USB Peripheral Controller

To

hostor hub


14/33


USB Transfers

nUSB is a master/slave protocol

n 4 types of data transfer:

Control [Endpoint 0]

Bulk

Interrupt

Isochronous

14


15/33


USB Software Layers

15

Application

Middleware

Class Driver

Host Stack

Hardware

Controller Driver

Host

Middleware

Application

Class Driver

Function Stack

Hardware

Controller Driver

Function


16/33


USB Software Layers

16

Application

Middleware

Class Driver

Host Stack

Hardware

Controller Driver

Host

Application

Class Driver

Function Stack

Hardware

Controller Driver

Function

Middleware


17/33


USB Software Layers

17

Application

Middleware

Class Driver

Host Stack

Hardware

Controller Driver

Host

Application

Class Driver

Function Stack

Hardware

Controller Driver

Function

Middleware


18/33


USB Software Layers

18

Application

Middleware

Class Driver

Host Stack

Hardware

Controller Driver

Host

Application

Class Driver

Function Stack

Hardware

Controller Driver

Function

Middleware


19/33


USB Software Layers

19

Application

Middleware

Class Driver

Host Stack

Hardware

Controller Driver

Host

Application

Class Driver

Function Stack

Hardware

Controller Driver

Function

Middleware


20/33


USB Software Layers

20

Application

Middleware

Class Driver

Host Stack

HardwareController Driver

Host

Application

Class Driver

Function Stack

HardwareController Driver

Function

Middleware


21/33


USB and Embedded Systems

21


22/33


Creating USB Peripherals

22


23/33


Using USB Peripherals

23


24/33


Both Sides of the Bus

24


25/33


USB On-The-Go

25


26/33


Typical OTG Applications

nPeripheral actingas temporary host

Camera to printer

Print without a PC

MP3 player to disk Load/unload songs

n Like-to-like deviceconnectivity

PDA to PDA

Data synchronization

MP3 to MP3File sharing

26


27/33


Host Negotiation Protocol

PDA

A-host

Browse web

A-peripheral

Cell phone

B-peripheral

B-host

Upload addresses

HNP


28/33


Nucleus USB Objectives

nProvide USB connectivity for Nucleus-powered

systemsnFast, small, portable and modularised

nGround-up design to take full advantage ofNucleus

nSource code and templates for easy porting

nSingle vendor solution

28


29/33


Nucleus USB Features

n Supports USB hostsand functions

n USB 1.1 and USB 2.0

nOTG support

n USB logo certified

nMany controllerssupported

n Key embedded CPUs

n USB class drivers

29


30/33


Function Class Drivers

30

Nucleus USB Function Class Drivers

Mass Storage

Human Interface

Device (HID)

CommunicationsDevice (CDC)

Printer

Still Image

Video

Audio

Media Transfer

Protocol (MTP)

Pict Bridge

MS Subclass

SCSI

HID Subclass

Keyboard

Mouse

CDC Subclass

Ethernet/RNDIS

Modem

Ethernet

Device Mgmt

30


31/33


Host Class Drivers

31

Nucleus USB Host Class Drivers

Mass Storage

Human Interface

Device (HID)

Communications

Device (CDC)

Printer

Still Image

Video

Audio

Media Transfer

Protocol (MTP)

Pict Bridge

CCID

MS Subclass

SCSI

CD ROM

Floppy

HID Subclass

Keyboard

Mouse

Power

CDC Subclass

Ethernet

Modem


32/33


USB The Future

nUSB has been subject to constant extension and

enhancementnSome less successful

USB OTG not as ubiquitous as expected

Wireless USB never took off at all

nUSB 3.0 coming

very high speed: 4.8 Gb/s

new power management

higher power delivery to devices

change in connectors

32


33/33

Colin [email protected]

http://blogs.mentor.com/colinwalls

Thank you
mailto:[email protected]://blogs.mentor.com/colinwallshttp://blogs.mentor.com/colinwallsmailto:[email protected]

USB Under the Hood

Documents

Transcript of USB Under the Hood