[sdiy] How to add MIDI IN to an old Casiotone 101

[Ullrich Peter]

Hi!

Instead of using that many 4066 you could use matrix switches. I used the MT8816 for my Poly61 midi interface and decoupling diodes.
For the Casio SK-1 I used the smaller MT8812 chip - but here without decoupling diodes so there is a limit to maximum two notes at one time.

The advantage of this method is that you don't need to know the timing of the synth - you just sit in parallel (4066) or quasi-parallel (Matrix circuit) with the keyboard matrix switches. But the material effort and so the costs are much higher...

Ciao
Peter
________________________________________
Von: synth-diy-bounces at dropmix.xs4all.nl [synth-diy-bounces at dropmix.xs4all.nl]" im Auftrag von "Tom Wiltshire [tom at electricdruid.net]
Gesendet: Sonntag, 29. Dezember 2013 12:49
An: Jack Jackson
Cc: synth-diy at dropmix.xs4all.nl
Betreff: Re: [sdiy] How to add MIDI IN to an old Casiotone 101

Yep, that'd do it. Some of the Korg Poly6 MIDI boards work this way. Using the processor to turn on analog switches (4066) in parallel with the keyboard allows you to have both MIDI and local control at once, if that's important. Otherwise, like you said, you could manage without.

http://www.acc.umu.se/~amber/Poly6/stuff/mpx61.GIF

On 29 Dec 2013, at 11:23, Jack Jackson <jackdamery at hotmail.co.uk> wrote:

> I have this old board, it's provides quite basic digital sounds from an NEC D990G chip. As far as I can tell, this chip also performs the matrix scanning of the keybed.
>
> So if one were to add MIDI to it, this is how I envisage it:
>
> 1. MIDI note-on message received
> 2. Microcontroller interprets note and uses a look-up table to tell it which position of the matrix this note fits.
> 3. Microcontroller waits until the switch for the notes row goes high
> 4. Microcontroller sends the correct pin high for that note.
> 5. Pin stays high until note-off is received.
>
> So the micro would have to sync (or at least follow) the onboard chips scanning and just output the 5v for that note at the correct time.
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