USB Overview

USB Overview
USB Overview
© 2008 Microchip Technology Incorporated. All Rights Reserved.
USB Solutions from Microchip
Slide 1
Topics
O
O
O
O
O
O
O
O
O
O
Need for USB
Benefits of USB
Speed comparisons
USB Evolution
USB Host / Peripheral / OTG
Embedded Host
USB Hub
Device Classes
Data Transfer Mechanisms
Application examples
© 2008 Microchip Technology Incorporated. All Rights Reserved.
USB Solutions from Microchip
Slide 2
Need for USB
O
Offering ease of use (Plug and Play)
O
Expandability (Port expansion)
O
Speed for the end user
O
Accommodate different applications simultaneously
O
Low cost
O
Self Powered
USB started as a standard for connecting peripherals (such as mice, keyboards)
to PCs. Now it’s the standard for connecting personal devices (iPod’s, printers) to
PC and personal devices (PDA, scanner) to personal devices (printer, iPod’s)
Microchip offers USB products – Peripherals, Embedded Hosts
and OTG in PIC18, PIC24 and PIC32 portfolio
© 2008 Microchip Technology Incorporated. All Rights Reserved.
USB Solutions from Microchip
Slide 3
Benefits of USB
O
One interface for many applications
O
Auto configuration
O
No external supply required
O
Hot pluggable
O
No user settings
Microchip provides with a scalable choice of integrated USB
solutions across 8-, 16- and 32-bit PIC microcontrollers
Offering packages from 18 pin to 100 pins
Easy-to-use and upgradeable products for embedded designs
Ample code and data space for complex USB applications
© 2008 Microchip Technology Incorporated. All Rights Reserved.
USB Solutions from Microchip
Slide 4
Buses and Speed
Comparison
© 2008 Microchip Technology Incorporated. All Rights Reserved.
USB Solutions from Microchip
Slide 5
USB Evolution
Spec
Data Rate and
Performance
Applications
Notes
USB 1.1 Low-speed
USB 2.0 Low-speed
1.5Mbps
Keyboard, mouse, joystick
Low cost but limited
performance; type and
number of endpoints
limited
USB 1.1 Full-speed
USB 2.0 Full-speed
12Mbps
Printers, audio derives,
webcams
Moderate performance;
guaranteed latency;
guaranteed bandwidth
USB 2.0 High-speed
480Mbps
Video, storage, imaging &
more…
Vast bandwidth
improvements. Adoption
in high-end consumer
segment
USB 2.0 On-The-Go
(OTG)
480Mbps or12Mbps
PDAs, MP3 players, cameras
Peripheral device can
communicate directly
without Host PC
Backward compatible
USB Wireless
(WUSB)
480Mbps @ 3 meters
110Mbps @ 10 meters
© 2008 Microchip Technology Incorporated. All Rights Reserved.
USB Solutions from Microchip
Recently specified. Still
going through adoption
process
Slide 6
USB Host
O
Manages and controls the bus
O
Initiates all data packet activity on the bus
O
Manages data flow
O
Error checking
O
Enumerates inserted USB devices and matches device to a
particular class driver
̶
Detects peripheral insertion / extraction
O
Provide Power
O
System typically consists of complex software applications with
an operating system and microprocessor
̶
Class driver needed for each device or class of devices
© 2008 Microchip Technology Incorporated. All Rights Reserved.
USB Solutions from Microchip
Slide 7
USB Peripheral
O
O
O
O
O
Peripherals only respond to Hosts and have no capability to
initiate data transfers Focus on power consumption
Detects communication from Host
Exchange data with host
Respond to Standard Requests from Host
Checking for error data from Host
Power Management
© 2008 Microchip Technology Incorporated. All Rights Reserved.
USB Solutions from Microchip
Slide 8
USB OTG
O
O
O
O
O
O
Host and Peripheral both in one
Focus on power consumption
Transceiver driver to support new USB On-The-Go protocols
̶ Host Negotiation Protocol
̶ Session Request Protocol
Full speed peripheral/host capability
One and only one Mini-AB receptacle, which can accept either a
Mini-A plug or a Mini-B plug
The ability to provide at least 8 mA of bus current when
functioning as the A-device
© 2008 Microchip Technology Incorporated. All Rights Reserved.
USB Solutions from Microchip
Slide 9
Embedded Host
O
Can support Limited resources
O
Supports a Target Peripheral List
O
Must be capable of supplying at least 8mA on VBUS
O
High, Full, Low-speed may be supported
O
Of the 4 USB transfer modes – Mandatory to support Control and
could support Bulk, Interrupt and Isochronous based on target
peripheral list
O
Example – Set Top box
© 2008 Microchip Technology Incorporated. All Rights Reserved.
USB Solutions from Microchip
Slide 10
On-The-Go Versus Embedded Host
Embedded Host
OTG
O
Limited host capabilities
O
Posses single role – host
capability to switch between the two
O
Devices have only Mini-A receptacle
O
Devices have Mini-AB receptacle
O
Does not require Host Negotiation
O
OTG devices must have Host
O
Limited host capabilities
O
Possess dual role - host or peripheral
Protocol (HNP) and optionally
support Session Request Protocol
Negotiation Protocol (HNP) and
(SRP)
Session Request Protocol (SRP)
O
Do not operate either as hub or full
host as normal host does
© 2008 Microchip Technology Incorporated. All Rights Reserved.
USB Solutions from Microchip
Slide 11
USB Hub
¾
¾
¾
¾
Keyboard
Supports maximum of 5 Hubs chaining
Hubs to offer power to all the connected devices
USB 2.0 hub must support all three speeds
Cascade upto 127peripherals including the root hub
Speaker
Hub
Logic
Analyzer
Hub
Hub
Hub
Hub
Data Logger
Hub
Up to 126 peripherals...
© 2008 Microchip Technology Incorporated. All Rights Reserved.
USB Solutions from Microchip
Slide 12
Devices Classes
O
Following classes have approved class specifications
Audio
Chip/Smart Card
Interface
Communication Class
(CDC)
Content Security
Device Firmware Upgrade
Human Interface (HID)
IrDA Bridge
Mass Storage (MSD)
Printer
Still Image Capture
Test and Measurement
Video
Microchip offers free source code for USB software stacks and class
drivers
Class drivers supported by Microchip are – CDC, HID, MSD and custom
© 2008 Microchip Technology Incorporated. All Rights Reserved.
USB Solutions from Microchip
Slide 13
Data Transfer Mechanisms
Control
Control
Control
+
+
+
Interrupt
Bulk
Isochronous
Guaranteed
Latency
Guaranteed
Latency
Guaranteed
Latency
Guaranteed
Data Integrity
Guaranteed
Data Integrity
Guaranteed
Data Integrity
© 2008 Microchip Technology Incorporated. All Rights Reserved.
USB Solutions from Microchip
Slide 14
USB Connectors
Laptops
USB Type A receptacle
PCs
Printers
Scanners
USB Type B receptacle
Set Top Box
USB Type A Mini receptacle
USB Type AB Mini receptacle
© 2008 Microchip Technology Incorporated. All Rights Reserved.
USB Solutions from Microchip
PDA
Slide 15
Application Examples
Host
Host
Traditional
PCc
Thumb drive
interface
Peripheral
USB OTG
© 2008 Microchip Technology Incorporated. All Rights Reserved.
USB Solutions from Microchip
Slide 16
Thank You
© 2008 Microchip Technology Incorporated. All Rights Reserved.
USB Solutions from Microchip
Slide 17
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