Autonomous USB MIDI interface

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Autonomous USB MIDI interface

Postby Synthex » Sat Nov 10, 2007 9:55 am

!!! UPDATE 01/02/2008 !!!

Hello Folks,

Here is my autonomous USB MIDI interface.
You can use my MegaDrum firmware with it !
Of course, it can be programmed in LVP !

Synthex USB MIDI Device v2.gif


Synthex USB MIDI Device TOP.pdf.zip


Synthex USB MIDI Device BOTTOM.pdf.zip


MegaDrum USB MIDI Firmware 18F2550 12MHz V2.hex



Regards,
Synthex
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Re: Autonomous USB MIDI interface

Postby baguette » Sat Nov 10, 2007 12:32 pm

As for the PCB, i recommend to look in your layout software for a function to fill the large spaces with copper (connected to ground) - this way you use less chemicals for the etching process.
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Re: Autonomous USB MIDI interface

Postby Synthex » Sun Nov 11, 2007 12:53 am

baguette wrote:As for the PCB, i recommend to look in your layout software for a function to fill the large spaces with copper (connected to ground) - this way you use less chemicals for the etching process.


It is a point of view ...

Here is this version !
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Re: Autonomous USB MIDI interface

Postby Synthex » Sun Nov 11, 2007 12:08 pm

Here is pinouts.
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Re: Autonomous USB MIDI interface

Postby Marctwo » Fri Nov 30, 2007 8:26 pm

This may be a stupid question... but what does the 6N138 do? I see it's connected to the midi ports, is it some kind of midi buffer for the eusart output?
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Re: Autonomous USB MIDI interface

Postby Synthex » Fri Nov 30, 2007 8:46 pm

Marctwo wrote:This may be a stupid question... but what does the 6N138 do? I see it's connected to the midi ports, is it some kind of midi buffer for the eusart output?


Have you seen the 6N138 datasheet ?
It's an "optoisolation", this is the standard Midi.

It is connected to the input and not output.

No buffer, just protection, electrical insulation
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Re: Autonomous USB MIDI interface

Postby Marctwo » Fri Nov 30, 2007 9:19 pm

Synthex wrote:Have you seen the 6N138 datasheet ?
It's an "optoisolation", this is the standard Midi.

It is connected to the input and not output.

No buffer, just protection, electrical insulation
Sorry, I'm very new to electronics... I did look it up but I haven't got a clue what optoisolation is. :lol: I obviously haven't reached that chapter yet.
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Re: Autonomous USB MIDI interface

Postby Synthex » Fri Nov 30, 2007 9:26 pm

Just made a small search on google using as a keyword 6N138.
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Re: Autonomous USB MIDI interface

Postby Marctwo » Fri Nov 30, 2007 9:36 pm

Yes, as I said I did look it up... and I found it... but data sheets generally make sense only when you already understand what the subject is. I also found it on several commerce sites but still couldn't understand it's purpose.

But I'm learning as now I know from you that optoisolation it is to do with 'electrical insulation'. ;)
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Re: Autonomous USB MIDI interface

Postby Lakedaemon » Sat Dec 01, 2007 10:17 am

I guess that we want to avoid ground loops or other nasty problems of the same kind.

Opto-isolation transfer the information with light without connecting the circuits electrically so that they can live in two separate electrical spaces (with different grounds, etc...)

Actually, the "only" electrical connection of megadrum to the computer is through USB (if you take out the optoisolator circuit of the digital board).
Last edited by Lakedaemon on Sat Dec 01, 2007 8:50 pm, edited 1 time in total.
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