hacking the Sony control-A1/A1-2 bus for fun projects

I've been toying with a project for controling my Sony amplifier, str-db940 using its control A1 bus.

My application is controling a single function (mute) using acoustic hand-claps (think bachelor appartement)

I have found some information googling, and have built a simple printer-port interface using just a transistor and resistor, described at the pages here:


Then, as I wanted windows XP support, I hacked a parallel-port driver found here:


It is timing the ups and downs of the serial waveform, taking an integer message value as input.

I have verifyed the waveform on oscilloscope, and I have managed to power on/off my amplifier. I take this as indication that the basic setup works. However, I have not managed to control any other functions. Part of the problem is that I do not now the device ID or function mapping for my particular amplifier. Internet sources are not that specific.

I have tried exhaustive search (by looping through the entire command space as well as 5- and 8-bit device ID space). Perhaps my amp use an even larger device ID. I am considering logging IR commandos from my remote control, as these messages are just IR commands with a pre-fix.

So.... Anyone think this sounds interesting? Any input would be appriciated. Perhaps any tinkerers out there that might want to join me?

best regards
Knut Inge

(I am running code in MATLAB, but the driver is accessible from the windows command-line. contact me for the source code)