[sdiy] microcontroller MIDI sequencer

[Blitzcraig]

I have found cheap(er) 12 POS rotary switches which I can set with 0-5v
and put straight into the ports of the HC12.  This would eliminate the
need for those voltages to be converted and quantized, etc.  This frees up
enough A/D's to do everything, plus a lot more.  The octave control and
note control will now be a rotary switch.  Because the sequencer will only
output MIDI, I don't see a need for a fine pitch adjustment, I will just
select 1 of 12 semitones and feed that into a Port register in the
microcontroller.  Same with the octave, but I will configure the switch to
go 4 octaves or something.

Now the problem exists that I don't have enough ports on the HC12 to read
each channel's 12bit note and 4bit octave.  My thought is to power each
channel right before it's being read and wire all 8 note rotary switches
to a single 12bit port.  Since the input is only used when that channel's
parameters are looked at, this should work, in theory.

The MIDI link is a great resource, I think it's what I was looking for. 
My question was what to output on which pin for note on/off, gate time,
velocity.  I think that page helps.

-Joe
www.blitzcraig.com


> Hi,
> I'm actually making something similar. In fact, this morning I got PCBs
for it from PCB fab. Mine is 16-step with only 2 parameters
(note/velocity), but can be configured other ways too.
> As I see, you need 33A/D inputs to achieve your goal. So make part of
existing 32 inputs multiplexed. Add 4052 or something like that, and use
1 I/O pin to toggle 4 inputs between 8 pots. Now you can have your
additional 8 octave pots, tempo pot and 3 others for
> whatever purpose.
>
> As for pots with 12 detents - Bourns makes 10-detents cheap
> slimline conductive-plastic pot's, so maybe you could search there for
12-detent version. Or use rotary switch.
>
> I'm not sure what you mean by MIDI I/O pins. Velocity and note is not
pin-oriented, it's a message on serial bus, so could you
> elaborate more what do you mean by that?
> But if you mean bits, go there:
> http://www.borg.com/~jglatt/tech/midispec.htm
>
> Roman
>
> ---- Wiadomo¶æ Oryginalna ----
> Od: Blitzcraig <blitz at nmt.edu>
> Do: synth-diy at dropmix.xs4all.nl
> Data: Wed, 19 Mar 2003 15:42:24 -0700 (MST)
> Temat: [sdiy] microcontroller MIDI sequencer
>
>>My new project is to create an 8 channel MIDI sequencer using a
> Motorolla
>>HC12 microcontroller.
>>The design is very basic...
>>pushbutton toggle (start/stop sequence)
>>tempo pot with numberic display
>>8 channels consisting of...
>>pushbutton toggle with LEDs (on/off)
>>gate time pot
>>velocity pot
>>note value pot
>>I have most of the code written, the HC12 has an onboard A/D (32
> channels
>>total).  I would like to have an octave pot for each channel, but
> this
>>would put me over the number of A/D channels available.
> suggestions?
>>I'm looking for a notched potentiometer for the note values (12
> notches),
>>suggestions?
>>I can't find a resource for standard MIDI pin I/O (such as which
> pin is
>>note number, velocity, etc.), suggestions?
>>Any other suggestions would help.
>>-Joe Craig
>>www.blitzcraig.com
>