MIDI Out as also MIDI Thru?

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djex81

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Hi I'm following the circuit here: https://www.pjrc.com/teensy/td_libs_MIDI.html for Teensy 3.x. Many MIDI controllers and synths today use the MIDI Out port as the MIDI thru. I am trying the achieve the same thing. Using this circuit for the Teensy is it as simple as connecting the received signal from pin 6 on the 6N138 to Pin 5 on the MIDI Out DIN?
 
I think you need to add some buffer (e.g. feed both sides of an AND gate or back-to-back NOT gates).
MIDIINTHRU-1.jpg
A merge out should be feasible but I don't do serial MIDI much and can't recall how easy it really is.
 
The way "thru" works in such devices is using software I think, since the use of the output port has to be shared
between local output packets and "thru" packets without mangling either. I think its common to be able to
reconfigure MIDI channels for the "thru" packets too in such a setup so as to be able to prevent channel clashes.

You can't get away with simply combining two MIDI streams at a low level, garbled packets will be very bad news,
leaving notes stuck on and all sorts of mayhem.
 
Yes, merge must be done in software but 'thru' ports can just buffer the input signal. It's to allow a master controller daisy chain sound moduals.

I was responding to the idea you could drive the port without a buffer but I didn't notice they mean to have a 'merge' output not a 'thru.'
 
The MIDI library does a THRU from input to the output by default. You have to shut it off if not needed, or attach the function to a switch or soft control.
 
ETMoody3 said:
The MIDI library does a THRU from input to the output by default. You have to shut it off if not needed, or attach the function to a switch or soft control.
Click to expand...

Oh wow I did not know this. Thanks for this info! Is there anywhere this explains this in more detail? I may want to have the option to disable this feature if it causes issues.
 
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