Camera Control Nodes

System Architecture

Master controls nodes over CAT-5 Ethernet.

Example Nodes

Possible Input-Output Formats:

• Servo Motor Drive
• Stepper Motor Drive
• TTL Switching Output
• Analog Temperature Input
• LVDS Communication

The Timing and Control Module:

• 50 MHz Data Clock Distribution
• 50 MBPS Serial Transmission
• 50 MBPS Serial Reception
• Transmit 32-MByte images

Reference Design

The CCS group proposes:

• Off-the-shelf ix86 processor in PC104 format
• Off-the-shelf input-output boards in PC104 format
• Custom input-output boards where necessary
• Linux operating system

Demonstration in Paris

Eric Aubourg and Laurent Guglielmi of APC-Paris 7 (IN2P3+) tried:

• AMD Geode board with 512 Mb RAM and 1 Gb flash memory "HDD"
• Minimal debian linux
• Compile C/C++ on VMWare similar system with full development environment
• Java Runtime (JRE) 6
• Compile Java on Mac/Win/Linux
• DMM IO board
• Digital 8-bit in/out
• Analog 12-bit in (8/16 ch)/out (2 ch)
• 100 kHz sampling
• Two lines of C to interface with Java
• A Java MBean represents its state

Demonstrated:

• Flashes lights fast enough to implement dimmer.
• Receives instructions from laptop running Java application.
• Reads thermometer and produces live temperature plot.
• Observed destruction of a PC104 computer several days after one analog output shorted.

Demonstration in Boston

Kevan Hashemi of Brandeis University tried:

• From WinSystems
• PCM-SC520 embedded computer, i486 133 MHz.
• PCM-UIO48A 48-line digital I/O card
• Embedded Linux System based upon Simply MEPIS
• Total price $1500 with flash card and power supply.
• Use PCM-UIO48A device driver binary supplied by WinSystems.
• Compile C-code on desktop Scientific Linux Machine.
• Copy compiled code to flash disk or transfer by ftp.

Demonstrated:

• Flash lights at up to 90 kHz.
• TCPIP transfer at 4 MBytes/s.

Implications

• Cannot compile device drivers on Scientific Linux for our ELS.
• Can compile drivers from source code in VMWare emmulator.
• VMWare emmulation of embedded system easy to install.

Recommend: VMWare for development.

• Byte-by-byte device drivers compiled from C are slow.

Recommand: Block moves or drivers written in assembler.

• Off-the-shelf IO boards can expose PC104 motherboard to damage.

Recommend: Thorough destructive testing of Off-the-shelf boards.

Suggest: PC104-format custom-made IO boards for speed and reliability.

Re-Examination of CCS Architecture

Move PC104s Outside Camera

Reduce Cables: Old-Fasioned Way

Reduce Cables: New-Fangled Way

TCPIP-Parallel Converter

The RCM4200:

• 60 MHz 8-bit processor
• 10/100 Ethernet and TCPIP Stack
• Byte-Wide IO Ports
• Real-Time Clock
• $100 in single quantity
• Byte-wise IO: 3 MBytes/s
• TCPIP IO: 500 kBytes/s
• Development environment available only for Windows
• Development environment costs $200.

Conclusion

With Linux computers in Camera:

• VMWare is effective platform for embedded Linux development.
• Java libraries provide open-source publish-and-subscribe protocols.
• Expect no problems adding DDS to PC104 modules.
• Doubt we can run LabView effectively on PC104 modules.
• For fast response, need to find fast IO boards and drivers.
• For rugged system, need to make or find rugged IO boards.

With Linux computers out of Camera:

• Can use TCPIP-Parallel converter modules to communicate with IO boards.
• Camera-resident electronics becomes simpler and more rugged.
• Provides fast response at IO Boards.
• Minimal load upon local network.
• Branedis has extensive experience with this solution.
• Shorter development time for camera contol nodes.
• DDS and other control software runs on larger, faster machines.