M110 synth chip

[Fraser, Colin J]

> -----Original Message-----
> From: jezz [mailto:jbrookes at bluebear.freeserve.co.uk]
> Sent: 07 December 2000 09:40
> To: Synth-Diy
> Subject: M110 synth chip
> 
> Anyone have a datasheet on this chip? It's an integrated keyboard
> scanner/divider chip used in a Jen SX-1000. I want to add 
> MIDI to my SX-1000
> and was hoping to do it using a PIC to read in MIDI and then 
> output lines to
> close keyboard switch replacements, maybe FETs or analogue 
> switches, or
> ultimately I'd like the PIC to interface directly to the 
> keyboard scanning
> lines as it would use a lot less external circuitry.

I just completed the v1 code for my AVR based version of a generic diode
matrix spoofing midi interface last night.
I'm going to post the PCB foil and code on my web site, once I've tested it
fully.
I've built it for a polysix, updating a design I did a few years ago using a
6502.
It should be adaptable to the Jen.
I've used 74HC374 latches to store the state of each key. The column selects
from the keyboard matrix drive the OE lines on the 374s, and the outputs
pull the row inputs low via diodes.
Total chip count for an interface to drive a 61 key keyboard is 11 ICs (AVR
2312, 6N139, 74HC138 and 8 x 74HC374) plus a diode for each output, a XTAL
and a few caps and resistors.
You'd only need 4 latches for a Jen.

However for the sx1000 I was going to replace the high frequency oscillator
with a vco and use an AVR with a dac to provide midi control.
Should be up and running soonish.

Colin f