Dreamcast G2 MIDI

[Dreamcast]

I recently tried connecting a XBOX 360 Rock Band 3 Clavier / Keyboard controller using its MIDI output to a Katana. I was interested in both seeing current generation hardware working with the Dreamcast without special adapters / converters and to see what the true functional limitations of the Dev.Box's MIDI ports are. The official MIDI adapter for the retail Dreamcast is connected via the Dreamcast's serial port, however the Dev.Box's appears to be directly connected to the AICA processor.

The one game compatible with the retail MIDI adapter is OTOIRE (a music creation software). I ran it in the dev kit and played a few notes on the keyboard. What I was playing was coming out of the speakers and I could use the keyboard's buttons to change patterns / octaves and pitch bend, etc, however I quickly realized it wasn't actually the game producing the sound, but the dev kit itself. To prove this theory, I reset the dev kit back to the system menu and was able to still play music through the Dev.Box.

Expanding on this, I remember seeing that the retail Dreamcast has two pins (49 & 50) on the G2 bus specifically for MIDI out / in respectively. I hard-wired the MIDI cable to those G2 lines hoping to get the same result as the Dev.Box unit, however there appears to be a problem. When I plug the keyboard into the Dev.Box, the keyboard knows, even without having the dev kit on, that a MIDI cable is connected and it switches itself into MIDI mode. But when connected to the retail Dreamcast, it only goes into MIDI mode when I remove the ground and just leave the current sink and current source connected.

Perhaps the Dev.Box has a logic inverter inline with it's MIDI lines and the retail unit requires one? Or maybe there are some pull-down resistors missing and the keyboard's signals are floating?

[cOcO!]

i would say there is some other cable left behind somewhere... maybe GND? it's fairly impossible to have something working with only 2 data cables and no other shit connected to it...

[Melchior]

Ah - spoken like someone who has not seen grounding loops and open circuits.

MIDI is generally OPTO-ISOLATED. (Part of the standard?) I'd just add some 4N35's to it... As I recall MIDI is weird.

Mabey a PC controlled MIDI port is the way to go? USB to MIDI cables are cheap and common now...(also - bit wise control for probing hidden features of the AICA)

[Dreamcast]

Lol, Melchoir. I meant to reply to this thread a few days ago. I discovered my opto-isolation faux-paux after looking at some MIDI-input schematics. Surely explains the problem I was having and I was a dunce for not reading the labels on the schematics I did see. "Current source / sink" should have been a big clue that the circuit wasn't directly connected.

Naturally, Radio Shack (my only "real" local parts supplier) doesn't carry isolators, so I'm going to try to get one off of an old ISA sound card.

[Jackie Harris]

Sorry to bump this, but did you have any luck getting a connection sorted? Direct MIDI input for the Dreamcast is a pretty exciting idea, especially since the official MIDI adaptor is almost impossible to find these days. I hope you made some progress!