The first C64 tracker with external sync? :D !!

Good work there. I was about to say that SidWizard has some kind of MIDI IN, but I guess that's not for sync'ing but just for entering notes (if even that?), but obviously it was precisely SidWizard that you had modified so you should know I guess. I am not aware of other C64 trackers that are sync'ed from an external clock. Dunno about Messiah though.. maybe that one can do that?

Other than that I guess the closest thing would be things like MIDI Slave and M64 (same name as your tracker?) that act as synth modules for external sequencers, but that do not contain any sequencers themselves.

It would be relatively easy to modify defMON — or any other C64 music editor really — in the same way that you have modified SidWizard, but I am not aware of anyone actually doing it, like you said.

(Otherwise defMON is typically acting as master. If you use the interface that scannerboy created, you can use defMON to send DIN sync and MIDI sync signals to external gear.)

Last edited by frantic (Oct 19, 2020 7:36 am)

Right. So.. regarding the implementation.. Do you basically count the number of incoming MIDI clock messages, and each 6th (or 3rd?) clock tick, advance the sidwizard player one tick? ...or were there any other complications involved?

And - yes there were a lot of complications, mainly related to clean timing. On both the arduino, and the C64 side. When main loop takes too long, polling user port can skip a tick. So you read correct, I am polling

A better version would use a hardware interrupt, but I found it works _so_ stable, that I continued working with a main loop. Polling this pin in a mini loop is just a few cycles. This must be fast. So it is < 10 microseconds.
After pin went high, I wait for pin goes low. Then comes the phase where is more time: call player (< $20 rasterlines time), and display stuff. I know that I can expect roughly 50% of vsync time to be free for me. That is a lot. Then after that I must be fast again, because the next HIGH signal will come soon.

Did I write understandable? I am happy to go into more details. Thank you for your interest!

PS: I have removed all MIDI stuff (via settings file) from SID-Wizard, to make space for my code)

Last edited by MARiO64 (Oct 20, 2020 1:41 pm)

Cool thread, i am also interested long time in MIDI implementations, especially on C64. For example, since i got 1541 Ultimate II+ cartridge of course I don't use floppy disk, and this device has got some incredible things for chiptune musicians, like two sid emulations (only 6581), there is also some Ultimate Audio module (7 voices for samples), and i have asked author of this wonderful device about some midi implementation, because i wanted to connect my midi keyboard to Cynthcart synth and play some things live, but up to now is not implemented, so at least i can use it in emulator VICE, where it works.

By the way, on github page i found some threat about it, and there is also some SID-Wizard MIDI in handling code:
https://github.com/GideonZ/1541ultimate/issues/16

Last edited by martin_demsky (Oct 20, 2020 2:23 pm)

>The problem I understand is very specific as your expansion port is blocked by C1541UII+ cartridge.

Yes. I know there is some cartridge Xpanders (you can use 2 or 3 cartridges at same time), but i don't know if it works with UII+, Cynthcart or some MIDI interface at same time. And that goodies alltogether are pretty pricy, i like to keep things easy, so i will see how i will manage that sync adapter for defMON with TD-3, that should be enough in this year.

Last edited by martin_demsky (Oct 20, 2020 4:05 pm)

Hi, sure if the code is very small I could probably put it in defMON too, yes. Send me a PM? The interface required is not available to buy anywhere I suppose? (Sorry I haven't checked that new youtube video yet although I should.)

It may also be relevant to say at this point that a new MIDI interface is in production. It uses the user port, and therefore does not collide with the cartridge port (for users of cartridges = most C64 users) or with the serial port (if using the HerMIDI interface). It has full support for both MIDI IN and MIDI OUT, and can be configured to generate NMI interrupts on incoming MIDI data. Furthermore, it can  be configured to filter out incoming MIDI data on certain channels, and it it also possible to configure it to only receive certain types of MIDI messages, to save some headache for the midi parser in the C64 in case a lot of MIDI data is sent that should not be handled by the C64 anyway. While the original defMON probably never will have a very developed type of MIDI support, it will still support MIDI sync IN and MIDI sync out using this new interface. At least that's the plan. (As I said before, MIDI/DIN sync out is already supported using Scannerboy's interface). I am also working on defMON 2 though, and that one will be more explicitly built around the idea of having full (whatever that means) MIDI support — using this particular interface — and it will also support for at least 3 SID chips (e.g. at least 9 channels). I have a prototype of the MIDI interface here, and it works very well. An initial batch of units will probably be produced in the next few months. My role has been to dream up the kind of MIDI interface that I would like to have, and a guy in New Zeeland and another guy in the Netherlands are making those dreams come true for me.

Last edited by frantic (Oct 21, 2020 11:47 am)

Alright. That makes sense. If you want to experiment with defMON some day, and want to "inject" some particular code somewhere. Just send me a PM and I can insert the code for you. Not in the "official" version, but in a temporarily hacked version.

As for the official version, I'll stick with support for the Scannerboy interface and (upcoming) support for that new MIDI interface (called "The Vessel").