Embedded board for playing back audio files
The client is a leader in the planning, production and installation of cable cars.
The goal was to design a self-contained board capable of playing back audio files upon external activation through a series of electronic inputs. The files to be played back needed to be simple to update and the board needed a built-in amplifier to be able to directly drive loudspeakers. The target operating environment was somewhat hostile with frigid winters and hot summers.
We were asked to manage everything: the client wanted a finished product, ready to purchase and install in bulk quantities.
- Requirement for flexible configuration
- Powerful audio amplification
- Ease of updating firmware
- All configuration placed in a human-editable INI file on an SD card
- Use of driver with integrated DAC and Class D amplifier to reduce power leakage and PCB footprint
- Firmware loaded from SD card
- Design and produce a self-contained board capable of playing audio files upon activation from external inputs
- Flexible configuration
- Hostile operating environments
- Hardware design, firmware development, production
- All configuration done through human-readable files on an SD card
- Use of open source technologies to reduce cost and development time
- High quality hardware reflected in very low failure rate
- Highly satisfied client
- Production and installation of over 500 units, deployment is ongoing
Advantages of our solution
The audio files were stored on an SD card, making it very easy to update them.
On the same SD card was a simple, user-editable configuration file specifying which files to play and for what duration, etc. This solution avoided the need for specialized software to reconfigure the board: a simple text editor and SD card reader are sufficient.
The firmware is likewise stored on that same SD card, making it just as easy to upgrade the board itself in the case of new firmware revisions.
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Advantages of our methodology
Working closely with the client, with short iterations, was key.
During the project our staff, thanks to their familiarity with open source and embedded environments, contributed patches to the FatFs project that improved performance and fixed small issues;
Advantages of open source
The project would not have been possible without two pieces of open source software: our real-time operating system BeRTOS and the FatFs library for accessing FAT file systems.
Without these two, the development time and cost would have exceeded the requirements
Planning, production, and installation of cable cars.
“Desiging a board completely from scratch, managing all aspects of the project from gathering requirements to overseeing production, was a huge effort that paid off when we delivered the final product to a satisfied client.”