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Well, I'd be more than happy to aid you in your quest to pick up assembly. We definately need more people writing their own sound routines.

Btw check out these:
Mastering Machine Code on Your ZX81, by Toni Baker - There's also a ZX Spectrum version of this book, but this one comes as a hyperlinked html version. Very handy, especially chapter 8.
How To Write ZX Spectrum Games, by Jonathan Cauldwell - Very useful once you've learned some basic assembly theory and are wondering how to put it into practise.

You'll also want a mnemonics table for a quick overview over all the available commands. I mostly use this one. It's missing a few undocumented opcodes, though. The definitive list of all Z80 opcodes is here.

Edit: Oh, and thanks for your contribution on bandcamp btw Glad to hear there's at least one person who actually likes my beeper poetry

Man, sucks to hear your stuff got stolen. But great to hear that doesn't discourage you!

ZXBaremulator uses the core from JSpeccy, which iirc has the same problems with beeper sound. Sound from the Pi itself should be fine.

Nice project, bummer about the sound emulation. Might be worth a try porting it to the C.H.I.P, though the timing issues on that machine will probably ruin the emulation.

Talkin' bout da tracker at Revision last weekend: https://www.youtube.com/watch?v=7UgSDAkXAJw
Rather technical, with a lot of uhhm and ehhm, and a failed demonstration of the QED68 sound routine at the end.

Well, generating a huge number of pin pulse channels is not a problem at least, thanks to Jan Deak's buffer method. I wonder though if it's possible to come up with an elegant algorithm that uses only one oscillator and derives the detuned copies from that, like the original SuperSaw supposedly does. For example, a simple 8-bit counter that increments once per loop iteration could already be enough to generate two derivatives (one added to main osc, one subtracted).

Well, trying to imitate the waveforms of the allophones is basically already a sort of proto-formant synthesis

Hybrid Qchan would be doable. Generally, almost any beeper engine can be combined with AY without too much trouble. The main problem is that adding AY would significantly increase row transition noise on most engines, because (re)loading the AY registers takes a lot of time. The other problem is volume balance. For example the classic Qchan is not a good candidate for combining with AY buzzer, because the buzzer is much, much louder. This is why I chose Squeeker-type synthesis for my hybrid experiment, because this type of synthesis produces very loud sound, and it also cloaks row transition clicks pretty well.

Well, as I said earlier, I've retired from writing beeper engines for the time being. So don't put your hopes on me. I do hope though that someone else will pick up these ideas, and I'm of course more than willing to help if somebody is to take up the challenge.

I think some MIDI solution would be preferable because of its potential impact. Would it be possible to ditch the Arduino MIDI shield and just decode the MIDI messages directly on the Arduino, using one of the digi ports? It would cause some additional load on the CPU of course, but on the other hand there's no need to load sequence/pattern data any more. As far as instruments go, yes, they could be pre-defined patches, but the engine should also make best use of the available standard Control Change messages, which could be linked to settings of duty, vibrato, etc.

Was just reading about this guy's troubles, so a software issue seems quite possible.

Perhaps it's easier to disable auto-reset until you've found the culprit?

Wow Shiru, looks like you're on a roll!

Since Arduino 1-bit seems all the rage now, I thought I'd give the avra+avrdude combo a try. Works like a charm, successfully produced a beep in asm!

Indeed, 16 MHz is a lot, especially considering the instructions are also super-fast. Guess I'll have to get used to writing purposefully slow asm code. Or just write complex enough routines, heh. Well, for now I'll leave things at "yay, my toolchain works" but next time I get bored with my other projects I might actually go and try writing a dedicated routine for this thing.

Edit: Wow, I just found out that ATmega has a fixed-length, 2-cycle MULtiply instruction. This should make it possible to implement stuff like 1-bit Phase distortion, perhaps even FM.

Awesome! Listening to the demo tune right now, and I can confirm there's no noticable artifact/carrier noise on my setup.

Well, would be great if this gets some exposition on the Arduino forums. If there's enough interest, we might even consider opening a special Arduino sub-board on here.

Alright, sucessfully uploaded garvalf's hex file with avrdude. The ELF doesn't run however, avrdude claims it's not valid. So I guess it's some intermediate thingy that's not meant to be uploaded. Well, no problem for now.

Good to see that the avr-gcc is reasonably efficient. Also, I still think it's very nice that you get annotated output with avr-objdump.

Still not sure if I want to install the latest IDE, especially not alongside the older install. If it were all contained in a standalone Java app then sure, but afaik it installs a ton of other stuff, namely all the avr tools. And I'm afraid checkinstall won't do the trick on this one.

I'm sorry but I don't have any octode demo tunes to offer. Have several snippets laying around but never managed to actually complete a song with it

So, guys, excuse my absolute electronics ignorance, but what would be the most reasonable approach to adding a line-out to this thing? Right now I have a PC speaker attached like garvalf, with some resistor thrown in for good measure.