Monthly Archives: December 2009

Arduino Trigger-to-MIDI converter

By glacial23 | 12/17/2009 - 1:09 am | arduino, electronics, Software, synthesizers 6 Comments

OK, the trigger-to-MIDI clock converter seems relatively happy (though I think the MIDI in on my AN200 isn’t? That’s going to require some more tests…).

I hacked on it a bit tonight trying to determine how drifty the generated MIDI clock was relative to the incoming trigger pulses from the DR-110. At first it was pretty ugly. I then added some compensation to the clocking to account for all of the work the Arduino is doing. After some trial-and-error, it’s relatively tight – total drift by my rough calculations was something like 10 milliseconds over a five minute period. Compare that to an earlier drift of 120 ms in a minute…

Here’s the code: trigger2midisync.pde

Hardware-wise, there’s a trigger input on pin 2 (use a zener if you’re worried about blowing stuff up…), and the MIDI out is the standard (TX, GND, and 5V through a 220 ohm resistor going to the pins of the MIDI port).

You may want to configure some of the #define statements in the code. STOP_TIMEOUT is the amount of time that needed without triggers needed for the converter to decide to stop. I’m using 2 seconds. Changing DIVIDE_SLICE would be important if your trigger source is something other than 4ppqn, and CODE_OVERHEAD_TIME is used to adjust drift in your deployment – 10 worked really well for me in my tests tonight, but it could be anything for others.

Once it’s hooked up and connected to your MIDI source and your trigger source, start sending a series of pulses to pin 2. On the first pulse, MIDI Clock start should get sent, and by the third pulse or so the sync will be “synced” – there will be an offset, but it should remain fairly constant. Now, once the pulses stop, clock will continue to be sent until STOP_TIMEOUT milliseconds have passed.

Next test will be syncing the DR-110 to the very-nearly-finished x0xb0x to see how well that keeps up – I did all my tests tonight with a Yamaha RY10, with both it and the DR110 just playing a “four on the floor” kick pattern.

Questions? Comments? Improvements?

Press The Button Podcast for December 16, 2009

By site admin | 12/16/2009 - 4:00 am | Contributors, Press The Button Leave a comment

Press The Button Podcast for December 16, 2009. Show notes are available at http://www.glacialcommunications.com/news

Building building building…

By glacial23 | 12/14/2009 - 2:09 am | arduino, electronics, General, synthesizers Leave a comment

Been a while since there was an update, so let’s see what’s on the bench of late:

x0xb0x – Yeah, I took the plunge and self-sourced a kit (not that hard since there’s a guy on the forums selling the rare parts kit for a reasonably fair price). It’s soldered up and mostly working, except for an extremely weird intermittent problem I haven’t completely solved yet. It’s unclear what the actual problem is, but I think I have a pretty good workaround ready to go. I also had issues with the USB chip early on, and then pulled since it was highly suspect when I first started having trouble. Now I’ll have to try to re-solder it again…
Haible varislope filter/phaser – Pretty much done! I think I need to reverse some of the pots and adjust some things, but it’s working reasonably well.
A trigger-to-MIDI Sync converter – Decided to do this with an Arduino so that I could at least clumsily sync my DR-110 to other stuff (x0xb0x, AN200, etc.). Code will be posted soon, once I add in start/stop functionality and test it a bit more thoroughly.
MIDIBox SID – I’ve got the CORE, SID, LCD, and a pair of Banksticks up and running. Worked great under computer/MIDI control, though I think a noise gate will be necessary for the bad 6581 VCA. Waiting for DINx4 and DOUTx4 boards, and then I’ll have to figure out the control surface – it will be more complicated than the basic one, but less complicated than the “full control surface”.

Whenever the PCBs show up, I also plan on building a pair of XR2206 VCO modules, as well as a few other modules on the horizon. Gotta start thinking about a new rack as well. I’ve got the first pair of Vector rails, but lining it all up is going to be careful work.

Also coming soon: A pair of PAiA Tube Mic preamps- the phantom on my mixer died (just as I got some condenser mics! curses!), so these are going to replace that functionality. I’m going to hotrod them a bit with better parts and some ECC83 tubes to replace the 12AX7s it ships with. Ordered some pedal PCBs as well – a Big Muff Pi clone, and a Rebote 2.5 delay.

I think I’m also going to have to move the electronics area to a bigger room with bigger tables, but that’s probably at least a month or two out.