Transcript NXP PowerPoint template

Introduction to USB
Agenda
Introduction to USB
LPC23xx Block diagram
MCB2300 demo
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Introduction to USB
Plugging the USB cable
Communication flow
Lets talk about USB applications
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USB- A Brief History
USB 1.1
Approved on 11/23/99
by the USB Core team
12 Mbps bus
Full-speed (12 Mbps)
Low-speed (1.5 Mbps)
Standard A connector
and standard B
connector
Interrupt (OUT) Transfer
was added
USB 2.0
OTG
Original USB 2.0
Supplements the 2.0
specification released
specification
on April 27, 2000
Connects peripherals
480 Mbps bus
High-speed (480 Mbps)
Full-speed (12 Mbps)
Low-speed (1.5 Mbps)
directly to each other
(peer to peer)
New mini-A
connector and mini-AB
receptacle
Backward compatible
with USB 1.1
New mini-B connector
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Plugging the USB Cable
Bus enumeration
– The process of identifying and
configuring USB devices
During enumeration:
– Assigning an address
– Reading “Descriptors” from
device
– Assigning and loading a device
driver
Host software responsibility
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Descriptors
Data Structure with a defined format that enables a host to learn about a
device and its capabilities.
Device Descriptor
Configuration Descriptor
Interface Descriptor
Endpoint Descriptor
Endpoint Descriptor
Interface Descriptor
Endpoint Descriptor
Endpoint Descriptor
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Introduction to USB
Plugging the USB cable
Communication flow
Lets talk about USB applications
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IN and OUT Transactions
Data flows IN and OUT with
respect to the host
HOST
“IN Transaction”
“OUT Transaction”
OUT
IN
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Endpoint Explained
An endpoint is a buffer used to transmit or
receive data
Each endpoint has a direction and an address
Up to 32 (16 pairs) endpoints can reside within a
device
Although a host has buffers, it does not have
endpoints
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Introduction to USB
Plugging the USB cable
Communication flow
Lets talk about USB applications
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USB Applications
Interrupt Transfer
Bulk Transfer
Control
Transfer
(Bus Enumeration)
Isochronous
Transfer
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Interrupt Transfer (1)
Device never interrupts the host.
Host polls the device
Only way low speed devices can
transfer data
Also used by the host to send
data to the device on a scheduled
basis
Maximum packet size: 1-64
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Interrupt Transfer (2)
DATA STAGE
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Bulk Transfer (1)
Used for large amount of data
Only full and high-speed devices
Host controller ensures that bulk
transfer are eventually completed but
it does not guarantee bandwidth
Fastest transfer type on an otherwise
idle bus
Maximum packet size: 8,16,32,64,512
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Bulk Transfer (2)
DATA STAGE
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Isochronous Transfer (1)
Fixed number of bytes per frame.
Bandwidth is guaranteed
No error correction – No ACK field
Used for continuous communication
of time-relevant information
(streaming data)
Full and high-speed devices only
Maximum Packet size: 1-1023
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Isochronous Transfer (2)
DATA STAGE
No ACK field
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Control Transfer (1)
Enables the host to read information
about the device (enumeration)
All devices must support Control
Transfers at Endpoint 0
Control transfers require both an IN
and OUT Endpoint
Talks to the device through Address 0
while enumeration
Maximum Packet Size: 8,16,32,64
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Control Transfer (2)
SETUP STAGE
DATA STAGE
STATUS STAGE
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USB Communication Blocks (1)
Transfer Types
• Control
• Interrupt
• Bulk
• Isochronous
Transfer
Transaction
Token Packet
Transaction
Data Packet
Transaction Types
• OUT
• IN
• SOF (Start of Frame)
• SETUP
Handshake Packet
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USB Communication Blocks (2)
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LPC23xx
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LPC2300 Family
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LPC2378 (1)
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LPC2378 (2)
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Dual AHB
Concurrent operations become possible:
–
–
–
–
Ethernet packet reception and transfer to SRAM
CPU Instruction Fetch
USB packet reception and transfer to SRAM
GP DMA
Dedicating AHB Bus to Ethernet is required to guarantee 100 Mbits/sec Ethernet
throughput without contention with other peripherals
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USB 2.0
Fully Compliant with USB 2.0 Spec
Supports Control, Bulk, Interrupt and
Isochronous endpoints
Scalable realization of Endpoints at Run time
Double buffering supported for Bulk and
Isochronous Endpoints
Supports DMA transfer on all non-control
endpoints
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Available USB Device Stacks for LPC2300/2400/214x
(list does not claim to be complete…)
Keil RL-USB:
– http://www.keil.com/arm/rl-arm/rl-usb.asp
Micrium µC/USB Device
– http://www.micrium.com/products/usb/usb-device/overview.html
Micro Digital smxUSBD
– http://www.smxrtos.com/rtos/usb/smxusbd.htm
HCC Embedded USB (EUSB) Device Stack
– http://www.hcc-embedded.com/site.php?mid=120
CMX-USB
– http://www.cmx.com/cmx_usb.pdf
Express Logic USBX
– http://www.rtos.com/page/product.php?id=6
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Available USB Host Stacks for LPC2400/ LPC3180
(list does not claim to be complete…)
Micrium µC/USB Host
– http://www.micrium.com/products/usb/usb-host/usb-host.html
Micro Digital smxUSBH
– http://www.smxrtos.com/rtos/usb/smxusbh.htm
HCC Embedded USB (EUSB) HostLite Stack
– http://www.hcc-embedded.com/site.php?mid=180
Express Logic USBX
– http://www.rtos.com/
OnChip Technology
– http://www.onchiptech.com/wb/pages/products/otusb.php
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