Sonova Communications - Firmware development

Reference report #4

About the client and the project

Phonak, a brand of the Sonova Group, has a versatile communication solution for hearing-impaired people in its portfolio with its Roger™ product line.

Roger™ covers two main markets:

Support for children with hearing loss in the school environment
Solutions for adult hearing aid users who want to understand better in noisy environments and over distance

The beautifully designed devices also offer exceptional performance features such as optimum audio processing in any everyday environment, the ability to operate several microphones in combination and, last but not least, connectivity with smartphones via Bluetooth.

CSA Engineering AG has supported Phonak in setting up the software framework and has been involved in the software development for the entire product line for more than 4 years now.

Roger™ products consist of several processors.

The main processor, an ARM from the SMT32 family, implements the application logic. Depending on the device, the interface consists of buttons only or also a graphic display with touch screen. The device can also be configured and updated via USB.
The dedicated DSP is responsible for processing the audio signal. The audio source is either a microphone array or an external source which is connected via line-in.
The digital communication protocol is implemented in an ASIC, which provides an audio network on the free 2.4 GHz band.
For some devices, a Bluetooth chip is also used to establish connectivity with cell phones.

CSA employees supported the Phonak team in the realization of the software in the main processor and in the communication ASIC.

Our services

Definition phase:

Conducting a feasibility study
Development of the implementation concept

Realization phase:

Development of the embedded software
Documentation of verification and validation

Specification phase:

Creation of the software specification

Transfer phase:

Handover of the development results

Technology and methodology

Technology

A simple STM32 derivative was used for the Roger Pen product.

In the Roger Touchscreen Mic product, a more powerful derivative was required to control the graphic display.

The software architecture is based on the Buildingblock Framework, which CSA has already implemented for several customers.

Rhapsody is used to implement the application logic.

The ability to insert the functionality directly into the graphical representation of the software increases the clarity and agility of the development.

Methodology

The use of the Buildingblock Framework has shown several advantages:
Encapsulation of tasks
Methodology to tackle RTOS aspects (concurrency) in a safe way
Reusability
Each product has the same structure (recognizability/maintainability)
Drivers are abstracted, different HW platforms are supported with the same SW platform

Over time, several products have been realized on the same code base thanks to the clear structures and high reusability of entire components.

A large part of the work for the CSA employees consisted of implementing the hardware drivers in such a way that the application could use the components safely.

In addition to some smaller drivers, the complete USB communication and the control and configuration of the Bluetooth chip were implemented. It turned out that the code supplied by the manufacturer often did not meet the quality requirements for an embedded product and therefore had to be partially rewritten.

Another aspect of the collaboration was the maintenance of the build environment, which covered everything from the source code project to testing and deployment. For this purpose, a reproducible environment had to be created that would enable the project team to handle the individual steps easily.

As experienced developers of hardware-related software, CSA employees are able to grasp subtle and difficult-to-reproduce problems in their entirety and search for a solution in a targeted and efficient manner.

Conclusion

CSA's involvement in the Roger™ product line goes beyond simply helping with software development.

The good integration into the team, the opportunity to contribute own skills and the responsibility that could be taken on made the cooperation with Sonova Communications AG a success story on both sides.