High Speed Digital Systems Lab
USB host for web camera
connection
Final presentation – Part A
Presenters:
Alexander Shapiro
Sergey Alexandrov
Supervisor:
Mike Sumszyk
Agenda
 Project
objectives.
 System architecture.
 Project flow.
 USB
basics.
 ISP 1362.
 Isochronous transfer.
 YUV video.
 Part
B project objectives
 Demo
Project Objectives


Implementation of SOPC interface for USB webcam.
 Learn and implement USB host protocol.
 Learn and implement webcam protocol.
 Learn SOPC Development tools.
 Understand NIOS II architecture.
 Building NIOS II softcore system.
Receive picture from the webcam.
 Convert YUV to RGB and display in Matlab
Development Environment

Altera DE2 board



Cyclone II FPGA


Programmable chip to implement any design.
Programming tools:


Provides USB support for host and device application.
VGA output (up to1600 x 1200 at 100-Hz refresh rate).
Quartus II, Nios II IDE, SOPC Builder
Debug tools:

Hardware and software USB analyzer.
System Architecture
Input
USB Philips ISP1362 controller.
Transfer rate: 12 Mb/s.
Philips ISP1362
USB Controller
USB 1.0
Port
Cyclone II FPGA
NIOS II
SoftCore
Output
On Chip
Memory
DRAM
Memory
Avalon Switch
On-Chip
Memory
VGA DAC (10-bit triple DACs).
Up to 1600x1200 at 100-Hz.
VGA Port
VGA D/A
converter
Logic Flow diagram
Payload
DATA in YUY2 format
1. Check errors
2. Compose YUV frame
3.Decode to RGB
4. Send to VGA buffer
Project Flow
Learn stage

Working environment
 SOPC
builder
 NIOS II
USB and ISP1362 documentation
 Take mouse demo as basis for USB system.

Host implementation
Initialize connection and open
communication port.
 Determine the kind of device.
 Request configuration descriptor.
 Learn basic device capabilities.

Webcam interface implementation

Probe and commit sequence.
Negotiation between Host and Video streaming
interface.
 Consists of Host`s requests with supported
streaming parameters (bit rate, resolution) and
Client`s confirmation/denial

Select video interface.
 Device is configured and ready to work.

Webcam interface implementation
Probe & Commit flow
Host and device
negotiate acceptable
configuration.
It may take several
iterations to “agree”
Mid-project milestone

Working webcam interface on NIOS II system




Initialization
Configuration
Bulk data transfer
No isochronous traffic support
ISO transfer over Philips ISP1362


Isochronous transfer is the most challenging
aspect of the USB protocol.
Main issue – absence of code examples.
 Almost
no help could be obtained from forums and
documentation.
 No guidelines for implementation in Programming
Guide.


Was implemented from scratch.
USB analyzer was irreplaceable in
understanding and debugging.
ISO transfer over USB
 Host periodically sends ISO IN
requests.
 Device responds with ISO
packets.
 Each packet consists of payload
and data.
SOF
IN
Payload
DATA 0
IN
Payload
DATA 0
IN
Payload
DATA 0
SOF
IN
 DATA is video stream in YUV2
...
 Header holds error checks and
End Of Frame indicators.
Payload
DATA 0
Isochronous transfer buffering

Challenge:



Data to be delivered and processed each mSec.
CPU on embedded system cannot handle data each mSec.
Solution: ISP 1362 supports double buffering for ISO
transfer



One buffer is proceeded while the second is filled.
1024 bytes in each buffer.
Toggle rate is configurable.
Debug tools: USB analyzer

USB HW analyzer is irreplaceable in debug.






Shows real traffic between host and device
Triggers on defined events
Clear log of USB packets
Showed what packets Windows
sends to USB device. Software
analyzer can show only driver level
packets.
Helped find source of bugs.
Made it possible to ensure that
host/device behaves according to our
expectation.
Decode YUY2 video format

2 RGB pixels are defined in each macropixel (four
bytes).



They share U and V components.
Natural bitrate is 2 bytes/pixel
Demands efficient real-time decoder to RGB
Part B Project Objectives

USB 1.1 Video implementation.

Integrate VGA controller.
 Implement real-time video streaming

USB 2 support.
 Migration

to DE-3 environment.
Code optimization.
 DMA
 Hardware

YUV to RGB decoder
USB 2 Video streaming to monitor
References
Philips Embedded Programming guide
 Philips ISP 1362 Data Sheet
 USB 2.0 Specification
 USB Video Class Specification
 USB Complete by Jan Axelson
 Google
