Midibox as Switcher advice sought (newbie alert :-)

Design Concepts
1

Hi guys.

I’ve been lurking around in the edges of the forum for a while, and finally (!) getting plans together for a midibox as modular synth controller. Trouble is, I’m not quite sure which to go for.

A midibox 64 = AOUT + SHX8 seems an obvious choice for CV control, but I’m looking for a way to use a midibox to generate 0/+5V logic. I’ve got some audio/CV routers/switchers on the breadboard right now that need simple 3 or 4 bit logic to select inputs/outputs. What would be ideal,  is for, as an example, MIDI CC3 values 0,1,2,3…etc up to 7, to toggle 3 DOUT pins to produce binary 000,001 etc up to 111. This with some interface circuitry would drive the control pins of the switching circuit.

For generating these MIDI CCs, rotary encoders would be a very ergonomic solution, given the crowded front panel of the planned synth, if they could be hooked up to the DIN inputs of one or more midiboxes.

Has anyone done this sort of stuff before? haven’t found anything in the forum so far…and anyone got any recommendations for which midibox to go for? a modded MIDIO128? I’m not a coder, but am expecting to have to do some programming pretty soon. ( when I’ve got a PC to run the software, and learned some more that is… :slight_smile:

Sorry for all the dumb newbie questions, but I’ve only been DIY-ing for a year or so, and that’s all been analogue synth modules. The midibox looks like the answer, but the switching thing is the main problem that keeps cropping up when designing control circuitry.

Any suggestions at all would be most welcome…

Cheers,

Dave

2

Hi Dave;

There are no dumb questions…

The midibox looks like the answer

it is… ;D

there are but few things that are not possible with midibox/mios

Don’t know how to do it but midio is the place to look.

Can you clear up for me where you need the logic for/what it does(how does the router work (link?)); this is not a trigger/gate, or is it?

If triggers is what you are after check the forum for the tr-808 clone or coron ds-8 midification

cheers, marcel

3

Hi Marcel.

I don’t have a link for the stuff I’m working on, as it’s all on bits of paper, and breadboard/perfboard right now. But a similar example is here;  http://www.uni-bonn.de/~uzs159/switch.html (BTW Rene’s site is an excellent place for synth DIYers…)

The switcher circuits are 1 source to many destinations, or many to 1 routers for selecting between different ±5v audio signals (eg.  VCO wave outputs), or ±5V control voltages (say from a LFO) , or 0 to +10V control voltages - for example from envelope generators. The stuff I’m working on uses common CMOS 4000 ICs - 4051, 4053, 4066, 4067 etc.

3 or 4 bit bit logic selects which input/ouput is active, simple as that. Well,…er… hopefully… :slight_smile:

Switching a 4066 should be straightforward with the MIDIO128, because it’s a simple logic controlled quad SPST switch.

It would be good to have a rotary encoder as the front end to generate midi CC values for the multi-way switches, as it’s footprint on the (crowded) front panel is much smaller than eg; 8 x tactile pushswitches.

As an example, one full rotation would produce 8 different consecutive values of a particular Midi CC, cycling back to the first value after 360 dgrees rotation. Each midi message would toggle 3 DOUT pins to the binary values 000 - 111. These 0/+5v pins would connect to the control inputs of the CMOS chips, switching the in/outputs.

As an example, using MIDI CC=3, value 0 would not toggle any pins, giving binary logic 000. Value =1 would toggle  pin 3 to +5v, with pins 1 and 2 at 0v, giving 001. Value =2 would toggle pin 2 to +5v, whilst pins 1 and 3 were set to 0v,… and so on up to value 7 where pins 1,2,3 were set to +5V = logic 111.

Another way might be to have the  midibox send 3 midi messages at the same time for a given encoder position, to  toggle 3 DOUT output pins. Maybe the midibox 64 can do this, as it’s already setup for rotary encoder input?

Hope this all makes some kind of sense. I’m planning on getting some boards from Mike or Smash soon, so any thoughts on which midibox app is most likely to be able to do this are welcome. I guess I’m going to have to set up a PC and learn about MIOS and PIC programming  ( gulp!) - For a learner, what’s the best route in to this? any thoughts? I already have a mac, but It looks like there’s more software for the PC…

Here’s hoping I can crack it and post something useful back here some day… :wink:

Cheers,

Dave