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Category: Bluetooth


Loundness filter for BlueMp3

I wrote an extension to the [BlueMp3]( firmware. Now you can use an loudness filter on the mp3-player. After reading the [VS1001]( [specs](, the [BlueMp3]( mp3-decoder, i noticed that it’s possbile to upload code to the dsp.This code can manipulate the current mp3 stream, so perfect for a loundness filter. I worked through the [VS1001]( [application note]( and wrote some routines to upload that [VS1001]( code to the chip. Then i integrated that routines into the [BlueMp3]( firmware. There is patch available for the 1.8 firmware but also the binary 2.5 firmware includes the loundness filter code.

[patch firmware 1.8](

[patch client 1.8](

[binary 2.4](

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K2send – Gui for BlueMp3

After reading the [CT article]( about the [BlueMp3]( player, i knew i need this piece of hardware. It’s an bluetooth mp3 player based on the Atmel [Mega128]( cpu. The firmware [source]( is available and the [client]( is linux based. So what do i need more to play around? I ordered the pcb and parts at [Segor]( The Bluetooth module and the Atmega was pre-solderd, because it’s not easy to solder [TQFP’s]( at home. The thing was build after a hour of soldering and worked perfect. But the bluetooth signal just worked over 5 meters. So i added an Lambda/4 antenna (thanks tobi) to the bluetooth module, which extented the coverage up to 20 meters. But what i really needed was a GUI to play my mp3s. Since iam [KDE]( user i deciced to programm my own Gui called **k2send**. I setup a [project page]( a [berlios]( for it.


[Picture 1](

[Picture 2](

[Project page](


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