Compatible with the SN76489 (code heavily modified!) open source arduino code by Littlescale
The code will be available for free of course to anybody wanting to mess around.
When use in conjunction with the MIDI device, SPSG vst will act as a controller with volume/pitch envelope generator and table!

PREVIEW

Just making sure. As a guy working on a sound driver (or three) and enjoys doing research on the MD and co., I've been more than a little surprised at how few people are even remotely familiar with the YM2612's timers, so I'm glad you're familiar with them and at least made an informed design decision.

I'll probably chime in again if I find something useful to contribute. Otherwise, good luck on your project.

Thanks I had to dig into YM2612 Timers for The FMDrive Vsti witch features CSM mode "speech synthesis control" ^_^
PM me  what you are working on unless it is top secret

I'll probably chime in again if I find something useful to contribute. Otherwise, good luck on your project.

I'm working on... something like this... for the Gameboy and I'm wondering if there aren't more flexible timers than HBlank on the MD Z80? Also, does the HBlank interrupt keep triggering during the VBlank period?

VBlank happens 50 times per second (for PAL)
HBlank happens 15625 times per second
So it should keep triggering

I have read that the Master System often use the Interrupt mode 1, meaning that when an interrupt occurs the Z80's PC register is set to $0038.
As you get only one entry, you have to choose whether you want VBlank or Hblank...

So good to see that there are more people taking some serious interest in the capabilities of the MD in terms of sound. Been a bit lonely in the MD scene to see everyone using the same drivers and never try new stuff with the hardware, and I applaud your efforts.

I am curious, though: Why did you choose to use the HBlank for timing? Could instead use one of the YM2612's internal timers to provide a much more flexible berth for timing than the HBlank's rigid timing.

First reason is because I tried to emulate the Master System features
However AFAIK, YM2612 Timers do not cause interrupts and we must check the counting elsewhere.
Timer A is the only one fast enough, it is 10bits and goes as fast as 18µs at 1111111111 but only goes down to 54Hz at 0000000000
slightly better then Hblank 64µs.
Timer A can also be in use by the CSM mode witch screw up the ability to have both.

Keep in mind that my aim here was to check what could be done on the real thing before integrating the feature in my Super PSG Vsti.
I am in no way an expert on the Z80 side and if someone got a better way to increase the artificial waveform pitch resolution, let me know

This is very cool, so does GENMDM already support this sort of HBlank trick to reproduce this effect?

AFAIK, no.
but I think it could be implemented directly in the firmware
You can still make this kind of PWM with two PSG channel slightly detuned.

I am curious, though: Why did you choose to use the HBlank for timing? Could instead use one of the YM2612's internal timers to provide a much more flexible berth for timing than the HBlank's rigid timing.