108 keys with velocity

Design Concepts
1

Hi all,

someone on the French forums needs to build a MIDI keyboard using 108 keys with velocity. So far, it looks like SPDT switches will be used.

What would be the best way to connect this to a MIDIbox?

There’s this way : http://www.midibox.org/forum/index.php?topic=5835.0

but it only supports 63 notes. (Two cores, eight DINX4s and a LOT of wire…)

I thought about using a matrix, but there’s nothing so far with velocity support and I wonder if the keys would be scanned fast enough.

So far it looks like the keyboard will just have a power input, keys and a MIDI output.

Any ideas?

2

QBAS made a velocity sensitive scan matrix for a keyboard…

http://www.midibox.org/forum/index.php?topic=6386.15

The 16x16 matrix is big enough, but I think he only made 12x11 as velocity sensitive.

Would be a good starting point if you can program in asm.

3

if you can program in asm.

Nope, only TRS-80 Color Basic, DOS batch and once modded a program made in Tcl/Tk.

I’ve never got to build my Microchip ICD2 clone to start learning ASM… I have all the parts, but my LaserJet IIP printer died last year (I bought a new scanner motor last week, should be getting it soon! -with COD brokerage fees… >:()

I don’t think I’ll learn ASM for someone else if I have other priorities during the next month(Off school from Dec 21st to Jan 21st) :

  1. Buy and program Flash ROMs for my Kawai K4r V1.4 / K4m V1.4 / K5 V1.3 / K5m V1.2 firmware upgrade group order.

  2. Buy 8x 6582 reserved SIDs from Wilba.

  3. Fix the #!$@;* sump pump check valve.

  4. Fix the noisy ADC stage in my Fostex DAT deck I bought 1-2 months ago.

  5. Fix my laser printer and start to build some PCBs for projects on standby.

… (+ two mono tube amps to restore, my Gainclone to get working properly, finish the speakers I started to build in 2004, repairing two amps with little-annoying problems, get an analog oscilloscope-> align three cassette decks and a few tuners, etc.) …

then if everything goes well, in a few years I’ll build the ICD2 and start working on MIDIboxes… -> That’s going to be in years!  (In the mean time, I get some parts while they’re still available)

4

SPDT switches are different than this one used in standard keyboard, so code that I use is not compatible.

5

SPDT switches are different than this one used in standard keyboard, so code that I use is not compatible.

I see… The person might build a Off-(On1)-(On2) switch system though, that would be closer to a usual keyboard.

Still… not sure of which switch type will be used, so there are a few steps to do before thinking about software and MIDIbox hardware…