Hi guys,
I've finally had time to do some more work with my B&O equipment. :) If you want to skip straight to my problem, look for the underlined text.
Because I've got a pair of Pentas standing in my basement not connected to anything, I got the idea that I wanted to connect them to my squeezebox. My thought was that if I were successful with this, I would replace the squeezebox with a Sonos system.
This sounds pretty straight forward: Connect the RCA outputs to the Line inputs of the Pentas, right? Yes, that would work.
But then again, that would be too easy. :) So I decided to buy a cheap DAC off ebay, and see if I could solder a power link socket to it, and use this as an input to the pentas.
This brings up another issue. The pentas need a trigger signal to turn on. While I could take this signal straight from the DAC, and power the pentas for as long as the DAC has power, this would mean that I would have to turn on and off the DAC whenever I wanted to listen to music.
I am far too lazy for this, so I looked into the DAC chip (PCM1793) on my DAC. Looking at the datasheet, it turns out that this chip has something named Zero flags. These are two pins on the IC that goes low whenever there is sound on the left or right channel.
This was a step forward, but as I didn't know much about what kinds of signals my squeezebox sent over the optical output, I had to find out whether or not these pins had any activity. Would the flags be high when i paused the music?
After some ninja soldering, i managed to get two wires attached to the two pins, and hooked up my oscilloscope. To my satisfaction, i found out that the pins did exactly what I needed.
Then I found an Atmel attiny2313 microcontroller I had lying around, and programmed it to pull a pin high whenever it sensed that either of the zero flags dropped low. This pin was connected to pin 4 of a Powerlink cable i sacrificed for the project. The left and right signal cables were connected to the corresponding outputs of the DAC. I run the tiny on 5V, and from what I have gathered on the forums, this should suffice as a trigger signal for the pentas.
Time for a live test. I hooked everything up (using my penta mk3 in my bed room for testing), put on some Pink Floyd on the squeezebox, and hey, everything works. :D
So I pull everything down and head for the basement to test on the pentas (mk 2) there. Nothing. They do not turn on.
Any advice? I have tested with my Ouverture, and they work perfectly with this. Is there any difference between the mk2 and mk3 I should be aware of? Voltage level? Minimum current?
Some pictures for your viewing pleasure: http://www.dropbox.com/gallery/158769/1/beo?h=4cc439
Best regards,
Magnus