MIDI-SYNC (was Re: simple MIDI?)

[Fraser, Colin J]

> From:	Mikko Helin [SMTP:MHELIN at tne01.tele.nokia.fi]
> Sent:	Monday, January 19, 1998 11:48 AM
> To:	synth-diy at mailhost.bpa.nl
> Cc:	MHELIN at tne01.tele.nokia.fi
> Subject:	Re: MIDI-SYNC (was Re: simple MIDI?)
> 
> >I thought once about a MIDI-Sync out for a sequencer, with a 4017
> clocked by
> >31.5K and some gates to provide start, data and stop bits, and of
> course a
> >hold
> >state where it waits for the next step of the sequencer.
> >For sending one (or two, three) command/s this is practical.
> >For receiving use shift registers, and a discrete logic.
> 
> Even when it's possible to build a discrete MIDI sync out for an
> analog sequencer, it's not much easier to build that decent
> microcontroller sync box. With an Atmel 87C2051 FLASH programmable
> 8051 compatible 20-pin uC chip (with UART) it's quite simple to do,
> and
> when you've done it once, you've learned how to use the same design
> for other purposes (and there are many like MIDI-cv, trigger-MIDI,
> MIDI controller input, DCO etc.). If the 2 kB of FLASH PROM is not
> enough, there are other models with up to 20 kB of FLASH PROM.
> 
Using a microcontroller is not much more difficult, but a lot more
equipment is needed to develop code, program roms etc. than to hardwire
a UART.
What I found easy, and cheap, is to get a late 1980's home computer with
a decent user port, and build a midi interface plus analogue/digital
input/outputs as an add on.
I have a BBC Micro (6502 processor) which has good interfacing and a
built in assembler. You can pick these up in the UK for next to nothing.
I developed my midi to cv convertor as an add-on for the BBC. When the
code was mature enough, I built an eprom programmer to write the code to
an eprom, and built a separate processor board that went inside the
cv/gate output unit.
At the moment I'm using the BBC as a DIN Sync to midi clock convertor
with a merged midi input for my master keyboard.I'm thinking of adding a
mulitplexed input to the built in DAC to scan some knobs for a MIDI
output analogue sequencer. This is easily developed with this kind of
setup - to efficiently develop something like this around a
microcontroller you'd really need in-circuit emulation etc.

Colin f