The main idea of this project is that it is prossible to control a software mp3 player with an external device.

This controlunit contains a display, which shows you the title, interpreter, actual playlist, count of playlists, actual song and then count of songs in the current playlist.

The communication between software and controlunit is realized with RS232 (serial interface).

The Atmel microcontroller in this controlunit regulates the control of the display and the input of the keys.
The keyboard contains 20 keys, which are controlled by a special keyboardcontroller-IC.
This IC sends a signal to the microcontroller when a key is pressed. The microcontroller processes this signal and sends it over the serial interface to the softwareplayer.
There the appropriate instruction is done.

The transfer of the display-data is rather simple. The softwareplayer sends title, interpreter, and so on .... over the serial interface to the microcontroller. The microcontroller re-arrange this data and sends it to the display.

The softwareplayer contains several different functions, like Play,Stop,....

Because we have programmed this player on our own it is possible for us to affect these functions when getting data from our controlunit (containing the different keys).

Connected is our controlunit and our pc/laptop with the software player with a normal serial cable (1:1).

This device is not really application-bind, that means it's not only possible to control a mp3 player.
It is possible to control any program. You only have to use the given (really easy) transmission protocol