STM32F4 Discovery Soft Synth

a_rocchegiani · ‎2012-06-26

Posted on June 26, 2012 at 18:36

Hi to all,

I started to develop a STM32F4-Discovery Soft Synth. A video showing it's first beta release is here:

http://www.youtube.com/watch?v=4JkhzH57Je4

In some post I view a interest to audio application using STM32F4-Discovery.

Can someone that have interest in audio processing give me some suggestion for the next release ? What kind of features to add ?

Mario Luzeiro · ‎2012-07-20

Posted on July 20, 2012 at 13:15

Hi Alessandro,

Your topic is with interest to me, because as I said, I tried once to start do something as you are doing (before STM32F4 uC).

I understand now your synth type. PCM+Env+LP

You already have ''global effect chain'', so I think is best to put here the processing that really changes the sound (compressor? expanders? etc..). In post-processing maybe only the ones that don't change much the sound, so the antialiasing could be appropriate in this case.

Regarding STM32F4 resources, when I thought to develop my synth, because I'm also music enthusiastic, I prefer lots of features (and nice sounds) synth than quality (sample and bit rate). So uC resources will be used to create nice (single) digital instruments (multiple voices).

So about the question you made:

''Some engineers who knows both DSP and STM32F4 limits, can definitely give me some advice on some realistic algorithms to try.''

In my case I prefer to have a nice synth generator with just one STM32F4, you maybe can make an architecture that can add a parallel STM32F4 to make the global effects and the post processing stuff.

For me as user point of view, this project will not catch me and I won't connect my midi keyboard to it if I ear a sound sample and realize that it is just a ''sample playback synth''.

One source I found for get very good ideas is to download the user manuals of synth keyboards. They have the block diagram and how things are connected and how could be used. It will be easy to an ''engineer'' to understand and think how can it be developed. (make sure they are not patented :S)

For example you can try the virtual version of KorgM1. Its a wavetable with synthesis .. much like the PCM+Env+LP but improoved.

Have fun!

If you follow this thread to another place / forum, please let me know to follow you!

MRL

baurand_christophe · ‎2012-09-19

Posted on September 19, 2012 at 13:53

Dear Alessandro,

For my hobbies, I plan to create some electronic instruments based on stm32f4 discovery board.

You said your project will be released as open source. So is it possible to send me your dev file.

For my project I will use some wavetable with postprocessoring to change the sound effect.

I will be very gratefull if you will share your work.

King Regards.

Christophe

medhayo · ‎2013-03-22

Posted on March 22, 2013 at 18:39

I'm not sure whether your interests extend to recording, but what about developing the audio recording example on the F4 Discovery? The example program (I have found) records with extraordinarily poor audio quality - surprisingly since the specs of the components suggest it should be able to get good results. You might like to try to find out the reasons for this and develop a proper audio application that can record in good quality. Features to include could be: automatic handling of file names without overwriting existing files; simple push-button to start recording; options for recording level and bandwidth/file format; better handling of the file system and FAT32; RTC; LCD etc.