I copy paste here my last message on rot's subject :

"Hello,

I open sourced the code here : https://github.com/AudrenThibault/root-drum-machine

feel free to contribute if you want.

have a nice day !"

And again, thank's to rot source code. Without his code I could not have done anything.
You can download the rom on the github link. It works on emulators but it's more stable on real nintendo DS. On DSI XL it runs too fast, on other DS it's ok.