USB Universal Serial Bus - eko didik · USB Universal Serial Bus Kuliah #10 TCK210 Teknik Interface dan Peripheral Original logo (wikipedia.org) Max 12 Mbps USB 2.0 (2000) Max 480

USB Universal Serial Bus

Kuliah #10TCK210 Teknik Interface dan Peripheral

Original logo (wikipedia.org)Max 12 Mbps

USB 2.0 (2000)Max 480 Mbps

USB 3.0 (2008)Max 5 Gbps

Aplikasi USB

Serial, komunikasi berkecepatan tinggi

Pokok Bahasan: USB● Mengapa digunakan?● Dasar-dasar: kecepatan, topologi, endpoint,

tipe transfer, protokol● Antarmuka Host dan Driver (Software)● Aplikasi di sistem embedded

Setelah mempelajari bab ini, mahasiswa akan mampu● [C2] menjelaskan perkembangan antarmuka USB● [C2] menjelaskan topologi sistem USB● [C2] menjelaskan kelas USB terutama HID dan storage● [C5] mendesain sistem mikrokomputer dengan antarmuka USB sebagai

device

Lane Hauck, “Embedding USB”, 2002

Mengapa digunakan? Menawarkan keunggulan

● Many standardized, low cost devices are available

● Connectors and cables are standard● USB devices are compliance-tested to insure

compatibility and uniform performance● Using hubs, multiple USB devices can share

one connector● USB devices can tell you about their

capabilities

Mengapa digunakan? Menawarkan keunggulan

● USB provides device power● USB devices can:

– Be put to sleep– Be awakened– Provide a system wakeup call

● USB protocol takes care of low-level details– Flow control– Error checking

● You decide how complex to make the firmware

Dasar-dasar USB

● Kecepatan● Antarmuka● Topologi● Endpoint● Tipe transfer● Hub● Host dan driver● Protokol

OWI-535 Robotic Arm Edge

Kecepatan Transfer● USB 1.0 (1996) and 1.1 (1998)

– Low speed is 1.5 Mbits/sec● Packet size is limited to 8 bytes

– Full speed is 12 Mbits/sec– 12 Mb/s is great for embedded

systems● USB 2.0 (2000)

– “Hi-speed” is 480 Mbits/sec● USB 3.0 (2008)

– Theoretical max speed is 5 Gbit/s

Antarmuka USB● Standar USB 1.x/2.0

● USB Mini/Micro 1.x/2.0

Panjang kabel: 5mPerlu hub agar lebih jauh

Pin USB (Standar)

● Pin 1 : VCC (5V)● Pin 2 : Data -● Pin 3 : Data +● Pin 4 : Ground

Pin USB micro-B 3.0

No.1: power (VBUS)

No.2: USB 2.0 differential pair (D−)

No.3: USB 2.0 differential pair (D+)

No.4: USB OTG ID for identifying lines

No.5: GND

No.6: USB 3.0 signal transmission line (−)

No.7: USB 3.0 signal transmission line (+)

No.8: GND

No.9: USB 3.0 signal receiving line (−)

No.10: USB 3.0 signal receiving line (+)

Antarmuka Host

Wikipedia.org

Kabel USB

Sinyal USB● Jarak maksimal kabel 5 meter

● Skema enkoding: NRZI (non return to zero invert)

Rec

eiv e

r

Kabel 1 kaki

Dri

ver

Kabel 5 meter

Sinyal USB: Kode NRZI

● a 0 bit is transmitted by toggling the data lines from J to K or vice-versa

● a 1 bit is transmitted by leaving the data lines as-is

Topologi: Star

● 1 host dapat melayani sampai 127 peripheral

PC

Hub

P

P

P

Hub

PPP

P

USB Host

Root Hub

Endpoints

● Endpoints are logical channels inside a peripheral device

– Diidentifikasi dengan tuple (device_address, endpoint_number)

● In hardware they’re addressable buffers (FIFOS)– Every host transfer includes a 4-bit endpoint number

and a direction bit● CONTROL endpoint 0 is mandatory● All others are up to the design● Endpoints are handy for separating data types

Up to 32 endpoints

Kelas Device

Kelas Peripheral / Device

4 Tipe Transfer

● Control– Mission-critical, highest error protection– Used to interrogate, configure and control devices

● Bulk (easiest to use and the most flexible)– Large, sporadic, use all remaining available bandwidth– Ex: file transfer

● Interrupt– Guaranteed quick responses (bounded latency)– Ex: pointing devices, keyboards

● Isochronous– Guaranteed data rate, but w/ possible data lost– Ex: realtime audio or video

Frame Data USB (Cypress)

• 12MHz = 1.5MB/s or 1500 bytes/ms (full speed)• Isochronous/Interrupt traffic have guaranteed bandwidth• Control traffic is “best-effort”• Bulk uses what is left

Video Audio Mouse Control Printer Printer

1 msec frame

SO

F...Isochronous Interrupt Control Bulk

SO

F

Hub USB

PCUSB USB

Device DeviceHub

USB USB USB USB

PCUSB USB

Device

Device Device

Hub: Memberikan Arus ke Device

HubUSB USB USB USB

PCUSB USB

Device

Device Device

500

100 100

500

HubUSB USB USB USB

PCUSB USB

Device

Device Device

500 500

Wall Wart

500 500

Hub: Device Lebih Banyak

HubUSB USB USB USB

PCUSB USB

Device

Device Device

500 500

Wall Wart

500 500

USB USB USB

Device

500

Easy way to expand and power devices

Kontroler Host dan Driver

Application

Class Driver

USB Driver

Host Controller Driver

Host Controller

IRP

Transaction List

Application

Host Controller

PC Simple Embedded

Implementasi PC Apps or class drivers create IO

Request Packets (IRP) USB Driver

• Processes IRP’s• Manages CONTROL pipe• Division of duties between USBD and HCD

is not defined Host Controller Driver (HCD)

• Provides abstraction– Of host controller registers– Of data transfer specifics

• HCD creates a transaction list– Schedule of transfers

Host Controller turns transaction list into packets

Application

Class Driver

USB Driver

Host Controller Driver

Host Controller

IRP

Transaction List

Implementasi PC: Kompleks App needs no knowledge of

• Which host controller is installed• USB signaling details• Bus utilization details• Transaction lists

App talks to buffers in your device using “pipes”

Most of the HCD/HC complexity is due to the flexible nature of USB

• 127 devices• Devices appear and disappear at random• Bandwidth must be fairly shared between

devices

Application

Class Driver

USB Driver

Host Controller Driver

Host Controller

IRP

Transaction List

Implementasi Embedded

Looks simpleThe hardware is simpleBut software is “low-level”

• Detect USB device attachment

• Detect speed• Enumerate devices• Suspend and resume devices• Manage error recovery

• Generate USB resets

• Conduct transfers

Application

Host Controller

Simple Embedded

RTOS Menjembatasi Host - Driver

• Examples– WinCE– Linux– VxWorks

Application

Class Driver

Host Controller

RTOS with aUSB

"Stack"

• Host Controller vendor may provide a small driver to make the chip look like something the RTOS supports

Implementasi USB

USB Host/Device

USB On The Go (OTG), 2006● Connect two peripherals together

– PC is not required (but still supported)

● Allow peripherals to awaken each other– Session Request Protocol

(SRP)

● Allow devices to exchange the host role– Host Negotiation Protocol (HNP)

● New OTG devices can tap into the existing 900 million USB devices

USB On The Go (OTG)● 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● Host turns on VBUS

● Dual-role USB devices:– Sometimes a peripheral, sometimes a host– Must use the new AB connector– Provide limited host capability– Supply 8 mA (min) on VBUS– Operate at full speed (high speed optional)

APLIKASI USB

USB Physical Hit Counter (AVRTiny)

http://www.bobhobby.com/2008/04/22/usb-physical-hit-counter-based-on-avr-attiny25/

Skematik

Kelas Peripheral / Device

USB Peripheral Dev Tools

Full-speed USB Development Board

Test USB

USBPCDevelop--Debug

Serial

Embedded Host

Full-speed USB Development Board

Add-on board contains USB host plus 4-port hub

PC USB

Serial

Develop--Debug

Test Host Transfers