DIN minimum scan time?

MIOS programming (C)
1

Hi,

my MIDI setup is really too large, which means that my Waldorf MIDIbay is getting too small… Thinking of alternatives, I was wondering if it was possible to hack a Core8 or Core32 with attached DIN and DOUT modules into a MIDI router? No processing of MIDI data is required, the task would be to just pass on any HI or LOW signal at a given DIN input to any (selectable, multiple) DOUT output. As this would have to be done faster than MIDI data rate, what is the DIN minimum scan time, and would this be feasible at all? I don’t have a scope, but maybe someone (TK?) could look into this?

Best, ilmenator

2

Hi,

using DIN/DOUT modules for this purpose doesn’t make sense! Scans wouldn’t be fast enough anyhow :wink:

Direct routing of MIDI signals can be achieved with simple multiplexers, such as 74HC151.

This chip routes one of 8 inputs to an output.

3 select lines allow to select the input

Circuit for a 8x8 matrix (without support for input merging):

  • 8 MIDI INs with dedicated optocouplers - the circuit looks similar to the known MIDI IN stage of the core module

  • 8 74HC151, route the outputs of the MIDI IN stages to the inputs of these chips (each MIDI IN connected to each chip)

  • the 74HC151 outputs can be directly used for MIDI OUT, just add 220 Ohm resistors as known from the core module

  • the 8x3 select lines of the 74HC151 could be controlled from a MBHP_DOUTX4 module

Best Regards, Thorsten.

3

using DIN/DOUT modules for this purpose doesn’t make sense! Scans wouldn’t be fast enough anyhow :wink:

Thanks, that’s what I needed to know - too bad.

The Waldorf MIDIbay is a 15x16 Matrix, which means that I am looking at a 32x32 design. Using discrete multiplexers will make this thing rather costly, as component count will increase exponentially.

Any other ideas anyone?

4

FPGA?

Best Regards, Thorsten.

5

Yes, though I’m a bit afraid of going that road… never done that before. But then, it sounds like a good reason to start with FPGAs!

6

I am looking at a 32x32 design. Using discrete multiplexers will make this thing rather costly, as component count will increase exponentially.

Any other ideas anyone?

Hi ilmenator;

I work on large matrix switcher for broadcast use, one type is a 32x32 which I happen to have an extra back plane for, it contains 4 AD8113 16x16 chips in a 2x2 configuration (which makes 32x32). They are serially driven so the SRIO driver would drive them. I will give it to you if you pay shipping. The chips at Digikey are a cool $50 each. It should not be too hard to reverse this board and use it.

info and datasheet here;

http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=ad8113

Some pix;

There are way more pins on the edge of the board then are used because they were designed to be stacked up to a 32x32x4 matrix and all the extra wires flow through the modules under them.

if you want it just pm me,

Good luck on your project!

Jmayes