MIDI to trig revisited.

[KA4HJH]

>At 12:19 PM 31/07/99 -0400, KA4HJH wrote:
>>I have one I got as a sample from Maxim. I was just thinking about this
>>last night. With a cheap PIC you could have lots of simple units instead of
>>a couple of big ones...
>
>Yeah, that's the idea, I was going to have one in each of my rhythm boxes.
>The only problem is finding a place to put the user interface. (switches
>and display). I'm having trouble deciding between these two options:
>
>1) Have a unit with 8 outputs in each rhythm box, with a dip switch to
>select midi channel and key range. The only panel mount would be MIDI
>in/thru, and perhaps power.
>
>2) Have a more comprehensive unit with 16, 24, or 32 outputs and use 9 pin
>DB connectors to connect to the rhythm boxes. The advantage is you have a
>nice user interface that is capable of many different modes. Also the only
>thing you have to install is a DB connector with wires going to trigger
>points. The bad point is: You have DB cords going to each device. Not a big
>problem I guess.
>
>Can anyone help me out here, I never was good at making life threatening
>decisions :-)

Here's what I've been thinking of doing:

1. Use a really effecient processor like a PIC--sorry Motorola, you're
still my favorite. Use two or three wire serial for all I/O. These devices
are daisy-chained in SERIES, meaning that you simply clock the entire queue
through the processor as if it were one device. Idiotically simple.

2. Read switches with a parallel to serial IC. You can have DIP switches
and a some front panel buttons with no hassle. Hell, you can even throw in
a serial ADC connected to some knobs.

3. Use serial DAC's for the analog output, and eight bit latches for
digital. The latter I'm not sure of the best scheme for, but I'm sure we
can get serial to parallel in there somewhere. There may be some practical
limits to the number of DAC's, but the number of digital outputs is almost
unlimited. I don't understand why all I ever see are midi2trigger devices
with 8 triggers. For another dollar (plus whatever connectors you're using)
you could just as easily have 32 or even 64 (OK, $2). It makes no economic
sense--at least make it an option. Put extra pads on the board!

4. If you use an LCD display--make it serial!

5. The tricky part--the software. The ultimate would be to make the
note/channel/message assignment for every output programmable. Beyond a
certain point you need a fancy interface with a display, or a MIDI patch
editor to do this. The configuration info could be stored in the MCU's
EEPROM or a serial EEPROM. You could program multiple setputs and change
them with patch change messages.

6. Connectors. DB's are a quick and dirty solution, especially for a
standalone unit. Somebody mentioned the high density connector used for
ultra SCSI--probably overkill here but attractive.

Running out of ideas...X)

Terry Bowman, KA4HJH
"The Mac Doctor"