I was looking at the schematic for the digital control board and noticed that pin 17 of the ATMega is leading to something labeled SECRET_MIDI_OUT - JP1.

On the PCB it seems to be a dead end just before the header.

What is it? Anyone know?

Thats what i will include on my next PCB…

It is the TX port of the second UART of the ATMega644p. During development it was used to pipe data out, first through a USB>serial dongle ; then through a second midi connector.

Currently, its sole use is to send CV data in digital format to the digital filter board.

You won’t believe me, but that was my guess. I was really hoping that it was some sort of treasure map.

I’ll keep looking…

But given it is a synth, having more MIDI outputs isn’t a lot of use :slight_smile:

I grant you, it was more interesting when it was a secret…

Should have left well alone then :wink:

Sometimes it’s better not to know.


The little secret pin no one should know about.
Revealed veil of mystery never let you sleep in calm.
This is the price for curiosity, this will never be unseen.

Maybe unexplained pins should be treated the same way as undocumented jumpers?

As Dave Haynie (hardware engineer at defunct Commodore) used to say:
"NEVER EVER mess with a PCB jumper you don’t understand, even if it’s labelled “SEX AND FREE BEER”

Schrab, I think that’s haiku?

Now that you mention that… maybe i should also try to solder sober?

Let’s take a vote: who thinks DMM solders sober? He produces the neatest builds ever known…

Titus, some kind of. I have not classified it yet.
whispering: who is DMM?

He is the guy that built the programmer/xt in this thread.