Optical time domain reflectometer (OTDR) is used in fiber optics industry for measurement and testing parameters of the fiber line. Our customer had OTDR device with based on Intel XScale microprocessor module. The OTDR device has replaceable measurement modules onboard: optical reflect meter, optical tester, optical spectrum analyzer, chromatic dispersion measuring instrument and others. The goal was to customize embedded Linux distribution to run from the XScale board and write user software for measurement process with account for various measurement blocks. 

Itransition Embedded Software team defined Embedded Linux distribution suitable to run from customer’s XScale board. Our extensive knowledge of Linux kernel internals allowed us to develop missing linux kernel drivers for LCD and some peripherals. Our specialists succeeded in running linux operating system on the device and GUI user applications in linux framebuffer. Qt Embedded Library was chosen to use for measurement application.

Running measurement process with various measurement modules:

• Reflectogramm viewing and zooming – measurement result;
• Reflectogramm analysing: filtering, automatic event search algorithm, spline interpolation;
• Saving results on JFFS embedded filesystem;
• Fine tuning parameters of measurement block;
• Software updating via onboard network interface.

System highlights:

• User-friendly graphical interface on 800x600 color LCD with touchscreen;
• Device design and onboard keyboard comply with strict usability requirements;
• Running Embedded Linux as a highly reliable embedded operating system;
• Remote management via Ethernet interface;
• Ability to save measurement data on removable storage such as CompactFlash card.

Embedded Linux distribution used by our engineers was based on Familiar Linux, which is widely installed on HP IPaq and Sharp Zaurus PDAs. This distribution has comprehensive facilities for packages repository management. Software package operations such as upgrade, install, install dependencies are managed by ipkg utility, which allowed us easy "software upgrade via network" feature implementation.

The measurement software was written in C++ object oriented language and uses cross-platform Qt-Embedded GUI library specially fit for embedded applications.

As every measurement block has its own measurement strategy and protocol, dynamic link libraries were developed implementing measurement protocol for each block.

Special optimizations to reduce operating system boot time were made. Customer?s logo is displayed during boot up thus hiding all unnecessary details before measurement application start.

Technologies used:

Efforts:  32 man-months.