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Creating a Board-Level Multiple Camera Array for OEM Applications
FLIR Systems, Inc. Posted 07/22/2009
Technical Application Note TAN2009001
Technical Application Note (TAN2009001): Creating a board-level multiple camera array for OEM applications
1.2. Applicable Product(s)
- Firefly MV (OEM models)
- 6-Port Board Level 1394a Hub
1.3. Application Note Description
This Technical Application Note describes some of the factors to consider and the specifics of how to construct a flexible, ultra-compact, multiple camera digital imaging system using an array of eight Firefly MV IEEE 1394a cameras, a custom Point Grey 6-port board-level 1394a hub, and third-party custom cables.
1.4. Intended Audience
This Technical Application Note is intended for original equipment manufacturers (OEM’s) of high volume vision systems. Some of the Point Grey products described within, such as the Firefly MV camera with miniature 1394 connector and the 6-port board-level hub, are available to qualified OEM’s only. Some minimum order quantity (MOQ) and lead time restrictions may also apply.
Many high-speed, compact vision systems, such as 3D scanners, object and gesture tracking systems, and multi-touch displays, have the following imaging requirements:
- Multiple cameras must acquire and stream images simultaneously from different viewpoints;
- Synchronized image acquisition from multiple cameras, either automatically in free-running mode, or by using an external trigger; and
- The cameras and supporting components must fit in a tight space, be placed in a unique position, or mounted within a custom enclosure.
This document will provide the following information:
- An overview of some of the benefits of FireWire and why it is an ideal interface technology for small, multiple camera systems;
- How Point Grey products can be used to meet some of the above requirements;
- Some of the technical factors that vision system designers should be aware of when designing with Point Grey products; and
- An example system configuration.
1.6. Multiple Camera Support
1.6.1. Selecting a Digital Interface
There are several things to consider when deciding on the interface technology for a multi-camera system, including total throughput, quality of service, latency, and overall system complexity and cost.
FireWire is widely regarded as the best interface technology for industrial and computer vision applications. It has guaranteed, truly isochronous bandwidth that is allocated every 125 µs for data that can be termed "latency-critical." This allows for low-latency data distribution and enables the latency of that data to be deterministic, making the interface technology ideal for operating multiple cameras on the same network. FireWire also allows for much smaller camera designs, like those of many analog cameras, and a single cable can provide both power and data. This maximizes ease-of-use and reliability of the system, and enables compact multiple camera imaging systems to be created with minimal cabling.
The Point Grey Firefly MV uses an IEEE 1394a interface, which provides data throughput of 400 Mbits/s.
- Article: FireWire: Blazing the Way for Industrial Vision
- Presentation: Past, Present and Future of FireWire and USB Technology
1.6.2. Multiple FireWire-Based Camera Arrays
There are many factors that should be taken into account when designing a large array of FireWire cameras. These include physical elements such as hubs, cables and host PCs, as well as other aspects such as image acquisition software.
Technical Application Note 2008001 provides an detailed examination of the various factors to take into consideration when designing and implementing a multiple camera array.
1.7. Image Acquisition Synchronization
All Point Grey 1394a and 1394b cameras, including the Firefly MV, support image acquisition synchronization. When in free running mode, the cameras are automatically synced to within 125μs at the hardware level. This is a feature of the cameras themselves, and is independent of the host system, camera drivers or software. Synchronization can also be achieved by triggering all cameras at the same time, either by an external trigger or by an asynchronous software trigger.
Point Grey’s MultiSync software can also be used to perform automatic synchronization of cameras
across buses. The software is also capable of synchronizing cameras across multiple PCs using a
dedicated IEEE1394 timing bus.
- Knowledge Base Article 241: Synchronizing image acquisition of multiple PGR cameras
1.8. Board-Level Products
The term “board-level” refers to a product that does not have a case or protective enclosure that houses the printed circuit board (PCB). This is often necessary to minimize space requirements or to allow the camera to be mounted within a custom enclosure. Board-level versions of the Firefly MV, Dragonfly2, and Dragonfly Express are available for OEM applications.
1.9. Example System
Point Grey Research has successfully demonstrated an array of eight Firefly MV IEEE 1394a cameras, a custom Point Grey 6-port board-level 1394a hub, and third-party custom cables. Point Grey Research does not endorse any of the third-party products mentioned or account for their performance in your particular setup.
|Computer||Sony VAIO All-in-One PC, model VGCLT33CE|
|Operating System||Windows XP Service Pack 1|
|Cameras||Point Grey OEM board-level Firefly MV camera with mini connector
Part numbers1: 97-00100-06900 (mono), 97-00100-07300 (color)
|Hubs||Point Grey OEM board-level 6-port hub with mini connectors
Part number1: 97-00400-00000
|Interface Card||Point Grey 1394b 800 Mb/s 2-port ExpressCard (FWB-EC-2PORT)|
|Interface Card Power Supply||Point Grey 12 V 1.25 A wall mount power supply (ACC-01-9003)|
|Software and Drivers||Point Grey FlyCapture SDK with FirePRO interface card driver|
|Cables (Card to Hubs)||Point Grey 6-pin to 9-pin 4.5 m 1394 cables|
|Cables (Hubs to Cameras)||8-inch custom cables, 8-pin JST to 8-pin JST
Newnex part number: CFS-JST8-08A
|Optics||6 mm M12 microlens|
1Some ordering restrictions and minimum order quantities apply
1.9.1. Imaging Components
22.214.171.124. Firefly MV with Miniature 1394a Connector
The Firefly MV can be fitted with a miniature 8-pin vertical connector in place of the standard 6-pin right-angle (vertical) 1394a connector. This model, available to qualified OEM’s only, is designed to minimize the amount of space required at the rear of the Firefly MV. The following Technical Application Note TAN2006007 - Wiring specification for Firefly MV mini 1394 connector documents the part number and pin configuration of the connector used on this model. This allows users to create their own custom IEEE 1394 cable for connecting to the miniature 1394 connector.
126.96.36.199. 6-Port Hub with Miniature 1394a Connectors
Hubs can help to extend the distance of Point Grey cameras, reduce the number of cables arriving at the host PC by consolidating connections, and provide additional power over the FireWire cable to connected cameras. The 6-port hub supports up to 5 incoming connections which then can be reduced to a single cable to the interface card on the PC (note that the total amount of data that can be transferred is still limited by the 1394 bus). Two hubs can also be daisy-chained together to support an 8-camera array off one 1394a host adapter card (requires external power to be applied).
- 65 x 40mm (see full dimensions below)
- One (1) flat 6-pin IEEE-1394a connector; five (5) vertical 8-pin miniature 1394a connector JST p/n BM08B-SRSS-TB(LF)(SN)
- 8 - 32 V via external barrel connector or FireWire
- 1 A per port at 12 V
- TI TSB41LV06A physical layer chip
- Status LED to indicate power and device connection
- Common mode chokes minimize physical layer port errors and failures
- 4 mounting holes
188.8.131.52. IEEE 1394b ExpressCard
- The Firefly MV 1394a camera is fully compatible with the 1394b ExpressCard. The only issues that users should be aware of are:
- Each camera consumes approximately 1 W of power. An external power supply must be connected to the ExpressCard to provide power to the cameras.
- The physical interface between 1394a and 1394b is significantly different. To connect the ExpressCard to the 6-port hub’s 6-pin 1394a connector requires a cable with a 1394a 6-pin connector on one end and a 1394b 9-pin connector on the other. These cables can be purchased from Point Grey.
- Using a 1394b interface card will not improve the camera's ability to transmit data. In other words, users will not be able to achieve higher resolutions and faster frame rates with their 1394a camera.
- The number of cameras that can be used to stream images continuously is limited by the IEEE 1394 chipset used. The LSI (Agere) chipset used in the Point Grey ExpressCard is able to support 8 simultaneous DMA contexts. This means that 8 cameras are able to stream at any given time.
184.108.40.206. Custom Cables
Point Grey does not provide the cables required to connect the 6-port hub to the Firefly MV. These are left to the OEM to source themselves. Newnex is one company that provides these cables.
1.9.2. References and Resources
Technical Application Notes:
- TAN2008001: Factors to Consider When Designing a Multiple Camera Array
- TAN2006007: Wiring specification for Firefly MV mini 1394 connector
Knowledge Base Articles:
- Knowledge Base Article 252: Technical overview of the IEEE 1394 (FireWire) standard
- Knowledge Base Article 241: Synchronizing image acquisition of multiple PGR cameras
Other Websites and Documents:
- Newnex 1394 custom cables
- Past, Present and Future of FireWire and USB Technology
1.10. Additional Downloads and Support
Access more Technical Application Notes on the web at www.ptgrey.com/support/downloads.