Midi is really quite slooow. at 30500 kbps
No MIDI works at 31250 baud.
As you say:-
To 'Correct' you have to be Correct.
You are not.
latency will always be an issue.
Rubbish, it depends on what you are trying to do.
Grumpy_Mike:
No MIDI works at 31250 baud.
As you say:-You are not.
Rubbish, it depends on what you are trying to do.
Sorry a typo.. Yes Latency will always be an issue, not like the 'Issues' you have, but not always a problem. for a stomp-box and sending Midi-sync (which is the issue at hand) it is an issue, but not always a problem, if you want to have a single sync master to multiple devices there are solutions to fix the issue. That all depends on what one is trying to do. The latency does depend on the amount of data actually being sent, but if it is just for sending a midi.start for instance you could put just a single note on a track receive midi from that track on the Arduino, send a midi.start and measure the time it took for it to get back. Mind you, for actual 'Live' work, which is what a stomp-box is usually for, a bit of latency tends to groove.
The latency does depend on the amount of data actually being sent
Yes it does, how could it not.
I know you are trying to help but in this case you are not.
Issue means problem. If its not an issue its not a problem, it doesn't affect the design and implentation.
What you are describing is colloqually called "a non-issue". Perhaps you meant "consideration".
Grumpy_Mike:
I know you are trying to help but in this case you are not.
i don't think you are helping either but let's leave it at that. As i am saying if you do not look at the issue specifically regarding how to implement 'sync' you may as well not consider doing anything. if you want a stomp box to determine the bpm by 'stomping' then the latency is 'not' going to be the main issue, but the responsiveness of your code will be (and the responsiveness to the sync you send by the DAW or any other audio program you want to use like GuitarRig.) butseriously the main issue here was the interference or other noise that needed to be removed... so let's just stick to the midi-specs and make sure that everything is properly mechanically shielded ! Now that is really helping.
Now that is really helping.
Carry on deluding yourself, but are not fooling me.
really appreciate all of your feedback!
it's a lot of info and I will look into it closely.
at the moment I found the H11L1M as a faster alternative to the 6N138.
I understand RL as a pull-up resistor. In my case the stompbox signal is already pulled-up at 3.3 V so I guess I could skip it.
Regarding VCC (5V in the above diagram), where should I get it from and what is its relationship to Vo? Should my VCC also be 3.3 V?
In my case the stompbox signal is already pulled-up at 3.3 V so I guess I could skip it.
Yes it is vital that you skip this to prevent damaging your stomp box.
Should my VCC also be 3.3 V?
It depends on what voltages you have inside your stomp box. I looked up the supply range of that buffer and luckily you can power it from 3 to 15V. So if you have a 9V battery in the box you can power it from that, the other side of the on / off switch. The output is open collector, which means you can safely connect it to the point you want to pull down.
However, given that you said :-
In my case the stompbox signal is already pulled-up at 3.3 V
I would just use an opto with a single transistor output. The speed increase you get from this is not going to improve anything that matters.
thanks a lot!
the idea of turning a stompbox into a true midi device (5 pin connector) is also appealing.
what kind of chip should get in order to translate midi protocol into stompbox signal?
orinocopaul:
what kind of chip should get in order to translate midi protocol into stompbox signal?
i would use an arduino 
and a schmitt-trigger, 2x 220R resistors and Bob's your uncle.
would it be possible though, to replace the arduino with a crystal and an ATtiny13 (or ATtiny24) for small applications?
the ic receives one midi signal - translates it into signal and that's it.
possibly yes, i have no experience with them, i get my pro-mini 's (or nano's) at less than E5,- a pop and the freedom to expand with LED's 7-segs button's switches and faders, plus the size and power usually not being much of an issue never made me consider the option. But if you try keep us updated !
orinocopaul:
would it be possible though, to replace the arduino with a crystal and an ATtiny13 (or ATtiny24) for small applications?the ic receives one midi signal - translates it into signal and that's it.
No, the AT tiny has no serial hardware. You might get away with software serial but I am not sure it will fit into the 13 or 24.
You will also need to write your own MIDI reader as the MIDI library will not work with software serial as I understand it.
grumpy mike
just noticed you're acknowledged in a similar project 