Development of USB 3.0 as a Camera Interface

By AZoOptics

Table of Contents

Introduction
Development
     Development Objectives and New Features
Application as a Camera Interface
About IDS Imaging Development Systems

Introduction

USB is the most widely used digital PC interface and is ideal for small devices that don’t have a power supply system of their own because of the integrated power supply through the USB cable.

Version 1.0 of the USB standard was released in 1996 and the slightly revised version 1.1 was released soon afterwards. Unique features such as hot-plugging, easy extensibility with USB hubs, and an integrated 5 V power supply made the new technology a better choice over the existing PC interfaces. Moreover, these characteristics pushed the direction of USB towards computer accessories such as keyboard and printer.

Version 2.0 of the standard with a maximum bandwidth of 480 Mbps, called as ‘Hi-Speed USB,’ was released in 2001. Since a transfer rate of 40 MB/s was possible with USB 2.0, it was broadly adopted for cameras, scanners, and external mass storage devices.

A decade after the launch of USB 2.0, today’s PCs equipped with high-speed interfaces like Gigabit Ethernet can provide bandwidths that are manifold the performance possible with USB 2.0, thus fostering the requirement for a faster version of USB. The specification for ‘SuperSpeed USB’ was released in November 2008.

New features on the hardware side as well as on the protocol level get rid of some of the limitations imposed by USB 2.0. This article discusses the development objectives, new features and application of USB 3.0 as a USB as a camera interface for image processing.

Development

The USB Implementers Forum (USB-IF), a consortium including Microsoft, Intel, HP, released the first revision of the new specification on November 12, 2008. Data transfer rates of around 400 MB/s are already feasible with FPGA-based host controllers.

Development Objectives and New Features

The new standard development focused on the following objectives:

• Improve the data transfer rate by a factor of 10 to reach 5 Gbps
• Maintain and support the current USB infrastructure
• Improve power management of connected devices
• Skip the polling procedure utilized in the earlier USB protocol

Table 1. The key differences between USB 2.0 and USB 3.0.

* A maximum cable length is not specified. These values indicate the estimated maximum length that is possible utilizing standard cables.

However, the following characteristics of the USB interface will remain unchanged:

• Topology: Star topology on up to five levels with USB hubs utilized for distribution. It is possible to connect as high as 127 devices
• Lower speeds are supported (Low-Speed, Full-Speed, Hi-Speed)
• Transfer and packet types (control, bulk, interrupt, isochronous)

The speed advantage of USB 3.0 is illustrated in Figure 1.

Figure 1. This bar chart shows the speed advantage of USB 3.0 taking the transfer of images with a resolution of 10 megapixels (8 bit color depth) as an example.

USB 3.0 is not intended to substitute the current standard 2.0. In the case of USB 2.0, devices may be referred as ‘USB 2.0 compatible’ albeit they don’t support the high data rate provided by Hi-Speed USB. For USB 3.0, a device that is capable of supporting the SuperSpeed data rate will only be referred as ‘USB 3.0 compatible.’

Application as a Camera Interface

The following advantages make the USB 2.0 interface an ideal choice for industrial image processing:

• Adequate bandwidth to concurrently transmit live images even from numerous cameras
• Its wide adoption in IPCs and embedded systems
• Easy connectivity without any external power source
• Chipsets that facilitate the development of compact and cost-effective cameras

Features available in robust GigE cameras are not viable in the USB realm with its roughly 40 MB/s bandwidth. The trouble-free, fast USB 3.0 connectivity is also especially useful for embedded applications that require a high camera resolution. However, a GigE camera is unsuitable because of it does not have a GigE interface and requires an external power source. The next-generation USB will also be suitable for laboratory or medical systems.

SuperSpeed USB is a useful device for camera manufacturers thanks to the more efficient, resource-friendly data transmission and higher transmission speed. The omission of polling and the support to the future utilization of Direct Memory Access USB controllers will enable the retrieval of image data from USB cameras virtually without any CPU load.

Although it is possible to operate most of majority of all image processing applications on USB 2.0 and GigE interfaces, the successor standards, USB 3.0 and also 10 GigE, opens new venues for the application of industrial cameras.

IDS Imaging Development Systems offers a suite of modern USB and GigE cameras in its uEye camera series for image processing applications in industrial and non-industrial environments. The company released its new USB 3 uEye CP camera series at the VISION 2011 held in Stuttgart.

With its novel features, the new camera sets a new trend in the market for industrial cameras. It is especially suitable for 3D and multi-camera systems in addition to challenging industrial applications. The integrated power supply feature makes the camera an ideal choice for applications in fields such as medical technology, embedded-systems, and microscopy.

The advanced USB 3 uEye CP camera series features high resolution CMOS sensors from Aptina and e2v. The extensive uEye SDK software package enables the integration of all cameras, irrespective of the interfaces USB 2.0, 3.0 or GigE interface, with the image processing libraries or custom applications.

About IDS Imaging Development Systems

IDS Imaging Development Systems, a key manufacturer of digital industrial cameras and frame grabbers, was founded as a ‘two-man firm’ by Jürgen Hartmann and Armin Vogt in 1997. Today the company employs more than 120 staff and is internationally represented by offices in the USA, Japan and France and through their network of distributors in almost all European and Asian countries.

IDS Imaging Development Systems’ customers include OEMs, system integrators and manufacturers in the industrial, security, scientific and medical industries. The company’s products are well-known for their consistent high quality, long-term availability and maximum ease of integration.

This information has been sourced, reviewed and adapted from materials provided by IDS Imaging Development Systems.

For more information on this source, please visit IDS Imaging Development Systems.