<html><head></head><body><div style="font-family: Verdana;font-size: 12.0px;"><div> </div>
<div>Ah, right, I didn't look at the datasheet for that restriction. The 3...4 x 48pin thing would still work, though. But as Roman Sowa said, one probably won't get a keybed that's not wired as a diode matrix.<br/>
As for tedious wiring, well, I wasn't thinking of doing that manually.<br/>
<br/>
Steve</div>
<div>
<div style="margin: 10.0px 5.0px 5.0px 10.0px;padding: 10.0px 0 10.0px 10.0px;border-left: 2.0px solid rgb(195,217,229);">
<div style="margin: 0 0 10.0px 0;"><br/>
<b>Von:</b> "Simon Brouwer" <simon.o@brousant.nl></div>
<div>Hi,<br/>
<br/>
That could only work up to 40 keys, since at most 80 of that processor's 144<br/>
pins can be used for I/O, and there are two contacts per pin to scan.<br/>
<br/>
The keyboard matrix with a diode per contact seems to me the more simple<br/>
approach.<br/>
<br/>
Best regards<br/>
Simon<br/>
<br/>
<br/>
<br/>
> On 05 April 2016 at 20:02 sleepy_dog@gmx.de wrote:<br/>
><br/>
><br/>
><br/>
> I wondered about this "scanning all the keys all the time".<br/>
> I'm only familar with stm32 platform (Also cheap! you could even get an<br/>
> stmf100 in a 144pin LQFP package for about 4,- EUR and do this even<br/>
> without any muxing matrix stuff or whatever way this is done with such<br/>
> keyboards :-D ),<br/>
> and there, I'd have, say, 8 ports of 16 pins each which are enough for<br/>
> 2x61 switches.<br/>
> So 4 ports are for all first-switches on all keys, 4 ports are for the<br/>
> second ones.<br/>
> So you might do 8 ports reads, taking 2 cycles each I think, @ 24MHz.<br/>
> Doing this in a timer interrupt at 8kHz seems feasible.<br/>
> Each of the 61 keys has a maybe 16bit counter.<br/>
> 24 MHz / 8000 Hz = 3000 cycles for all this stuff, I think 2 cycles x 8<br/>
> ports, + some checking logic which ports are not all zero and then<br/>
> looking in more detail at the bits of those which aren't, + (worst<br/>
> case) 61 conditional increments fit well in those 3000 cycles. You might<br/>
> even be able to display stuff on an LCD or so with that same processor.<br/>
> If that 144pin beast is unwieldy, 3x 48pin LQFP stm32f030 for 0.8 €<br/>
> each, each scanning 1/3 of the keys, one being master and joining all<br/>
> the MIDI event streams to one, might do?<br/>
> Or maybe I'm talking nonsense because one can't access all the keyboard<br/>
> lines that way and one really has to use some kind of muxing logic?<br/>
> I faintly remember somethig like that with the Fatar synth action keybed<br/>
> I have lying around... Alas I did not have time yet to build the<br/>
> monstrous MIDI controller I envision, but am glad to have bought this<br/>
> before Doepfer apparently stopped selling them... SO who says buying<br/>
> stuff you don't need right now has to be bad... :-D<br/>
> Oh, on a tangent again...<br/>
><br/>
> Steve<br/>
><br/>
> Am 05.04.2016 um 18:47 schrieb Ingo Debus:<br/>
> >> Am 05.04.2016 um 13:43 schrieb Richie Burnett<br/>
> >> <rburnett@richieburnett.co.uk>:<br/>
> >><br/>
> >> Is it reasonable to expect that I could use a low-end micro (e.g. PIC) to<br/>
> >> scan a 61-key Fatar velocity sensitive keyboard with sufficient velocity<br/>
> >> resolution to work well?<br/>
> > Maybe there’s a smarter way than scanning the whole keyboard all the time?<br/>
> > For instance, in wait-for-key mode all the keys are in parallel, so when one<br/>
> > key is pressed, the processor can react very quickly (thus measure the time<br/>
> > very exactly), without knowing at first which key it was. Then, while the<br/>
> > key is travelling, the keyboard is scanned to find the key. Then the<br/>
> > processor waits until the key hits its final position and measures the time<br/>
> > again.<br/>
> ><br/>
> > It would also be less noisy, because the keyboard is only scanned when a key<br/>
> > actually is pressed.<br/>
> ><br/>
> > Some problems might arise, what happens when a key is pressed while another<br/>
> > one is on its way?<br/>
> ><br/>
> > Ingo<br/>
> > _______________________________________________<br/>
> > Synth-diy mailing list<br/>
> > Synth-diy@dropmix.xs4all.nl<br/>
> > <a href="http://dropmix.xs4all.nl/mailman/listinfo/synth-diy" target="_blank">http://dropmix.xs4all.nl/mailman/listinfo/synth-diy</a><br/>
><br/>
> _______________________________________________<br/>
> Synth-diy mailing list<br/>
> Synth-diy@dropmix.xs4all.nl<br/>
> <a href="http://dropmix.xs4all.nl/mailman/listinfo/synth-diy" target="_blank">http://dropmix.xs4all.nl/mailman/listinfo/synth-diy</a></div>
</div>
</div></div></body></html>