[sdiy] MIDI velocity

[Amos]

I'm curious to hear if others have noted significantly different switch
timing (relative to actual played velocity) for black keys versus white
keys, on those Fatar keybeds.

My experience is that the black keys seem "hotter" than the white keys,
enough that I have to use separate curves for black versus white to get
consistent-feeling MIDI velocity output.  I chalked it up to geometry and
physics and went about my way, but I didn't notice any similar comments so
far in this thread so I thought I'd ask if it was just me experiencing
this...

-Amos

On Wed, Apr 13, 2016 at 9:24 PM, <rsdio at audiobanshee.com> wrote:

>
> On Apr 13, 2016, at 12:20 PM, Neil Johnson <neil.johnson71 at gmail.com>
> wrote:
> > I wrote:
> >
> >> About 7 years ago when I was writing the keyboard scanning code for a
> >> Siel Opera 6 I had a simple scheme for scanning and measuring play and
> >> release velocity (not many folks seem to know about release velocity
> >> although some synthesizers do recognise it).
> >>
> >> Using an Atmel ATMega8 scanning the entire keyboard every 1ms I run
> >> 4-state state machine for each key, where the states are UP,
> >> GOINGDOWN, DOWN, GOINGUP, and an 8-bit counter for each key.
> >> Debouncing is handled by the algorithm rather than a separate
> >> debouncing step.  With the right encoding of the states you can do
> >> most of the testing and state transitions using btiwise operations, 8
> >> keys at a time (on a 32-bit processor you could do 32 keys at a time).
> >>
> >> I'll try and dig out the code and sling it up on github sometime.
> >> It's all in C, no assembler required.
> >
> > Found it, and hosted up on github:
> >
> > https://github.com/nejohnson/kbdscan
> >
> > The keyboard scanner talks to a 74LS154 on the keyboard assembly, and
> > generates key on and off events with associated velocities.  There's
> > also code for reading some analogue inputs and a footswitch, but
> > that's not important right now.
>
> Thanks for sharing this!
>
> I was going to suggest that having the 'LS154 on the keyboard assembly is
> a great design choice, because that allows a simple, 14-pin connector, but
> then I realized you probably were stuck with that choice because of how the
> Siel Opera 6 was designed. Sure enough, looking at the schematic I see 8
> row bits, 4 column address bits, power and ground. (feel free to swap the
> row and column nomenclature as you prefer - Roland seems to use the
> opposite terms)
>
> Brian
>
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