[sdiy] MIDI VOL PEDAL with no micro??

[Scott Gravenhorst]

Dan Snazelle <subjectivity at hotmail.com> wrote:
>thanks for the practical advice!!
>
>
>ive made midi things with an avr before and other than trying to 
>get my friend comfortable with learning some code ( or pasting 
>some) i think its the easiest way to go 
>
>
>just what exactly would you do with shift registers, and a ADC... 
>in other words, the CC message, if you wanted to make a CC #1 
>pedal...would it just be the same conversion to 1's and 0's over 
>and over?? 

The ADC could be a bit of work too if done all in CMOS.  It would work the same way it
would work in an AVR, yes, a loop that gets the ADC value (converted from the pot) and
constructs the CC #1 message (3 bytes if you ignore running status).

>
>i wonder ( from the bending angle) if you could get any good 
>results from sending sporadic bursts of 8 bit digital information 
>via an opto to a synth? 
>
>

The data needs to be structured into MIDI messages.  You could simplify slightly by not
using running status - then you'd always send 3 byte messages.  In that case if you sent
random data as the third byte (forcing bit 7 to zero), you would then be sending a CC
message at some regular interval with a databyte that is random from 0 thru 127.  Dunno how
useful that would be, probably depends on the user.


>
>Sent from my iPhone
>
>> On Feb 8, 2014, at 2:30 PM, "Scott Gravenhorst" <music.maker at gte.net> wrote:
>> 
>> 
>> Dan Snazelle <subjectivity at hotmail.com> wrote:
>>> is it possible to create a MIDI volume pedal with nothing but an 
>>> optocoupler, opamps, cmos and passives? 
>>> 
>>> 
>>> i ask because i have a friend who wants to make one himself
>>> 
>>> id just use an AVR with an opto and a pot based pedal.... but i 
>>> thought it might be fun to go the other route 
>>> 
>>> 
>>> are CC messages complex? i wouldnt dare try this with SYSEX but i 
>>> thought a CC pedal might be within the realm of possibility! 
>>> 
>>> 
>>> thanks
>> 
>> I'd use the AVR or a PIC.  But yes, with enough CMOS parts you could
>> make a state machine that could handle it.  However, you'll need to add
>> a UART and bit clock (unless you want to build that out of CMOS too). 
>> In my view, the complexity is enough to warrant a uProc.  Think of all
>> the things the uProc would have to do - all of that would have to be
>> represented in CMOS logic.
>> 
>> 
>> 

-- ScottG
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-- Scott Gravenhorst
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