I have continued to dig into the mysteries of Wave Blaster (WB) connectors, daughterboards, and DB-50XG MIDI. To recap, the objective is to find how to convince a Yamaha DB-50XG to send MIDI data, if at all possible.
A closer look at a DB-50XG confirmed that both MIDI IN and OUT are definitely connected. Pins 4 and 8 of the WB connector are connected to pins 15 and 16 (I think!) of the Hitachi H8/3002 MPU. Those are the Rx and Tx pins, so that makes good sense. The signals are routed all around the daughterboard.
So technically a DB-50XG is definitely capable of outputting MIDI data. Whether it can actually do it is a different question. Without detailed documentation or a firmware dump I’m just guessing.
Even if it does work, the next question is whether bi-directional MIDI communication is possible on a typical PC sound card with a WB connector. But there’s more about that too.
The original Wave Blaster is said to be very very similar to an E-mu SoundEngine module, for which good documentation exists. And the SoundEngine clearly supports both receiving and sending MIDI data. So if the Wave Blaster is a SoundEngine, it would make perfect sense that Creative cards implement MIDI IN (from the host’s perspective) on their WB connectors, as documentation and multimeter suggest.
But I don’t have a Wave Blaster, so I can’t try that. I have a Wave Blaster II, which is a significantly different device, and I could find no hint of how it might be coerced to send data. Again, the WB II has both MIDI IN and OUT connected.
Looking at my WB card stack, it’s clear that the majority only implement one MIDI direction. That includes Roland devices and nearly all others except Yamaha.
The exceptions are Pine Tech PT-202 and Hizon DB333. The PT-202 uses a Samsung KS0164 synth, which is not terribly well documented. The datasheet talks about “Sequoia Pegasus synthesizer firmware” but it’s anyone’s guess what that is exactly.
The Hizon DB333 uses a Dream SAM9233/Crystal CS9233 which is well documented as such, but does not come with firmware. The CS9233 datasheet mentions separate firmware documentation… which is nowhere to be found. Given the lack of documentation, it is impossible to tell whether the daughterboard might produce MIDI output or how.
The DB333 is a bit mysterious because MIDI OUT from the SAM9233 is routed to pin 20 on the unpopulated JP3 connector, and from there presumably to pin 8 on the WB connector. But the trace is broken between pins 20 and 19 of JP3. That’s visible here.
The weird part is that some totally different DB333 has the trace broken in the exact same way. Probably not a coincidence. Then again, yet another specimen does not exhibit such damage. It’s bizarre, really.