Korg Poly800/EX800 Users

On Fri, 2010-10-22 at 06:38 +0000, zoinky420 wrote:

> If I were Mike looking for another project to tackle I'd stick with
> kits to modify cheap existing hardware.  If someone were to be awesome
> enough to make a MIDI-clock mod for the Akai ME-20A arpeggiator I'll
> bet it would go over well since the only mass-produced standalone
> clockable arp is the Oberheim Cyclone as far as I know.

It wouldn't be hard.  Get an arduino, write a program for it that sets
the serial rate to 31250 baud, hang an opto-isolator off the serial
input and you've got a MIDI interface.

Now tell it to toggle an IO pin high when it receives 0xfa (START) and
low when it receives 0xfc (STOP).  For bonus points make it pulse a
second pin when it gets 0xfa and not pulse it when it gets 0xfb
(CONTINUE) but still bring the run pin high.

Next we have the tricky bit.  MIDI clock is sent at 24ppqn so for every
crotchet note we receive 24 0xf8 (CLOCK) messages.  Every time you get
an 0xf8 increment a counter.  If you want to generate semiquavers you
need to divide this by four, so every time you count six CLOCK messages
pulse the clock output pin (or rather, pull it high for three and low
for three).  For bonus points, have several outputs with different
division rates so you've got 16 steps per 4/4 bar, eight steps, four
steps, dotted 8th and so on ;-)

Gordon MM0YEQ