How to build midimerger without powersupply

[Rednas]

Hi

I try to build the midimerger with the old PIC. I got all the stuff and soldered most part but i tried to build it without external powersupply.

What i do is I use the power on the cable from one of my keyboards. The other is still isolated with an optocoupler (6N138). This should work fine.

The problem is I connect the data cable directly to the PIC. But normally the databit is 0 if data is sent. This will light up the led in the optocoupler, so the optocoupling works and gives a 1 to pic.

Is this true?

And should i just set either an inverter or an optocoupler between data and PIC to solve this problem.

Thnx for answering.

yours

Rednas