Proj-2012-2013-Audioprothèse DIY-G2

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The Team

Marion Dalle and Rémi Piotaix, are engineering students of [[Polytech'Grenoble]] in 4th year, in [[Projets_2012-2013#RICM4|RICM]] (Computer Networks and Multimedia Communication) with a network and system speciality.

Project objective

Our projet is an hearing aid. The price of industrial hearing aid is very expensive and we will like create a cheap model.

Technologies used


  • card stm32f4-discovery

Progress of the project

The project starts the 14th January 2013 and takes place in [[Polytech'Grenoble]].

WEEK 1: January 14th – January 21st

Discovery of project. We chose this subject and we tried to create specification.

WEEK 2: January 21st – January 28th

We decided to use a stm32 card and we begin at using of this card. We played with the led to understand the card functioning using IAR IDE working on Microsoft Windows.

WEEK 3: January 28th – February 4th

First look of Demos provided by ST Microelectronics, compilation with IAR and flash into the card. For the next week, we decided to try to use a Makefile to compile the projects with GCC under Linux OS instead of using the embedded compilation toolchain of IAR which we don’t understand as well as a Makefile.

WEEK 4: February 4th - February 11th

Compilation of the summon ARM toolchain, a compilator based on GCC specialized for the compilation of programs for microcontrollers. The first version we tried (4.7) was buggy and didn’t want to compile our sources.

WEEK 5: February 11th - February 18th

Compilation of an older version of the toolchain (4.6). This one worked well and allows us to compile simple programs for the card using a project template found on the web.

WEEK 6: February 18th - February 25th

We tried to compile the Audio demo we found on the ST Microelectronics website but, with our skill, it was impossible to tweak the project template’s Makefile to obtain something executable.

By the same time, the research of a signal processing library in C was still infructuous. The need of searching in C++ was a real problem because we don’t have dynamic allocation on the card.

WEEK 7: February 25th – March 4th


WEEK 8: March 4th – March 11th

The idea of searching an operating system to run on the STM32F4 comes to us and we found a RTOS called ChibiOS which supports our microcontroller. We managed to compile it without problems. We also made a little program to test the system.

The use of ChibiOS gives us the possibility to allocate memory dynamically which allows us to use, if we found one, a C++ library for signal processing.

WEEK 10: March 11th – March 18th

We read the docs about ChibiOS and particularly about its Hardware Abstraction Layer in order to understand how to use it to make the microphone working.

WEEK 11: March 18th – March 25th

We found some libraries but none of them can run on the STM32F4. They are all in another language that C or C++ which are not ported to the microcontroller.

The only one that was in C/C++ was OpenAL but this one relies on others drivers for sound input/output which are not available on our card.

WEEK 12: March 25th – April 1st

We found a template for ChibiOS and the STM32F4 board on the web. This one comes with a Serial Over USB driver which allow us to access a shell to run commands on the STM32F4.

In order to test that, we wrote a little program to understand how it works.

WEEK 13: April 1st – April 8th

Preparation of the PowerPoint, report, etc…