[sdiy] Possible MIDI interface powered by MIDI driving device...

[Tom Wiltshire]

Nice work, Dave. I always enjoy having a look at someone else's approach to stuff I've thought about or worked on.

Steve T's comment about 5V not being a reliable supply suggests to me that for things like this (let's call it "creative rule-bending"?!) we should use uPs that can operate from 5V down to 3V or so. There are such things, so this shouldn't be too difficult to organise.

Tom


On 24 Mar 2016, at 18:47, "Dave Brown" <davebr at modularsynthesis.com> wrote:

> I did my own AVR design of a MIDI processor powered by the MIDI device.
> Details, including code, are at
> http://modularsynthesis.com/processor/processor.htm
> 
> I use this for a variety of reasons, but one of which is filtering out
> Active Sensing and Timing Clock.  Note that power stealing isn't supported
> by the MIDI standard and people on this list have criticized me for doing
> so, but it works quite well on a number of different synths.  Unlike what
> you posted, I went with an unregulated supply and a crystal for the AVR so
> the timing would be accurate.  I found that combination worked better.  All
> you have to do in the code is strip out the commands that echo the byte to
> the output.  You can strip the transpose and stuff also or just hardwire the
> pins.
> 
> Borrow away ...
> 
> Dave
> 
>> -----Original Message-----
>> From: Synth-diy [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of
>> Jean-Pierre Desrochers
>> Sent: Thursday, March 24, 2016 11:13 AM
>> To: Synth-diy at dropmix.xs4all.nl
>> Subject: [sdiy] Possible MIDI interface powered by MIDI driving device...
>> 
>> Here is a possible MIDI interface that would sink its power from a MIDI
>> driving device...
>> 
>> http://www.arcenson.com/public/MIDI_interface_power_steeler.JPG
>> 
>> ---> Assuming that the driving MIDI device (keyboard, sequencer, pedal
>> ---> board, etc..) is powered by internal +5VDC supply..
>> The CPU would have to sink its 5vdc thru the 220 resistor of the driving
>> device. Doable..
>> I also think that it could work since the CPU MIDI output would be
> 'opticaly'
>> linked with the final receiving MIDI device.
>> Both driving and receiving devices would avoid ground loops while a CPU
>> process is running between them..
>> 
>> A friend of mine asked for a simple 'MIDI active sensing code (FE)'
>> hardware filter working without a DC supply..
>> 
>> JP
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