MIDI on / off issues (1.61) [fixed in 1.70]

[fidgit]

first of all: merci beaucoup for the nice and very comprehensible kit, xavier! 

i built it yesterday with quite some experience in soldering kit assembling. as the subject says, i'm having issues with MIDI. some MIDI notes are simply ignored, when they still get triggered, they usually last for ever, ie no MIDI note off is received. besides this phenomenon everything seems fine.

i did check other forum entries on that topic and did what was recommended. yes, the optocoupler is correct, yes, i did try another MIDI cable, yes, i made sure that the MIDI settings are correct, yes, i'm using a very simple MIDI keyboard which is attached directly to the preenFM. no drivers, no USB interfaces and such.

in a post, i found that:
> . On the attached picture, I've colored all the connections involved in the Midi input.

however, i wasn't able to find this picture mentioned above. could you / somebody please repost it?

merci & meilleurs salutations

[6581punk]

I would check the resistor values around the MIDI in. Too big a value and the input won't work. Always check for soldering issues too

[fidgit]

yes, thank you.
i'll dig into it at the end of the week.

[6581punk]

I had a similar issue on the MIDIBox project I built, I had put the wrong resistor (too much resistance) in the MIDI input and as a result the signal was at too low a level.

I suspect in your case it could be an intermittent issue as well. Which may explain why it receives some data some of the time.

When you play a note on the keyboard it sends a note on and a note off value, the note will continue if it doesn't ever receive the note off value.

[Xavier]

6581, this resistance thing is very interesting.

Fidgit, the picture is attached at the bottom of the message.
You can see/download it ony when you're logged in.

Let me know if you can see it,
(i'm in vacation with limited conectivity, sorry in advance if i cannot answer quickly)

Xavier

[6581punk]

6581, this resistance thing is very interesting.

Well an opto isolator is basically an LED and a phototransistor, so if you use too big a resistor this limits the brightness of the LED too much nothing gets received the other side?

[funkyfli]

I noticed on my UM880 a quick succession of midi messages would not work.  This might be due to the fact that it sends out 4 Active Sensing messages a minute... continuously.  And, this may be bogging down the PreenFM?  I have not noticed an issue on my MOTU 828mk2.  Maybe, I should compare the voltage output between the 2.

[Xavier]

Any adidional information by people who have note on/off problem are welcome.

It's always difficult to know who's fault it is.

Funkyfli do you mean it does no work you UM880.
Doe you have other sound module that work with it ?
What do you mean by "This might be due to the fact that it sends out 4 Active Sensing messages a minute... continuously."

[funkyfli]

With the Edirol UM880: It does not receive all note on / note off messages.  It seems I need to hold a note for a decent amount of time to get a 'note off' received.  It also receives only a small amount of NRPN messages when using the VST.  All my other synths work fine with it... Nord Lead 2, Micro Q, Evolver, Tetra, Shruthi.  I cannot, however, send OS updates to the Tetra which I put down to the 'Active Sensing' messages... I could be wrong.

Active Sensing - System Realtime Message: 11111110  http://www.midi.org/techspecs/midimessages.php
A good explanation... in English:  http://www.planetoftunes.com/sequence/activesense.html

If you have any ideas of what to test for I am happy to help.

Martin.

[Xavier]

Thanks for the info and the URL.

I give a look at the code and i think that the 'active sensing' message cannot cause a problem. They are simply ignored.
To be 100%sure, can you disable 'active sensing' on your EMU880 and check if that change something ?
Or do you know a sequencer that can send this midi messages ?

I use the same 6n137 based midi schema as the shruti-1 so i don't think it's a hardware problem.

Le me know if you find something, i'll continue investigating,

Xavier

[funkyfli]

Well, I found a way to filter out 'System Realtime' messages from one channel of the um880...  This did not solve the problem:(   So, I guess this wasn't the issue.  Sorry.  I'm stumped.

[Xavier]

Thanks for having checked... that's really usefull...
If we eliminates the possibilities one by one, we're going to find a solution 

[6581punk]

Can you use the MIDI thru port on one of your devices to send the output to your preen?

[funkyfli]

Good idea.  Same results unfortunately.  MicroQ works correctly while the PreenFM does not.  Two adjacent messages (Note off, Note on) kill each other.  It might be something to do with the maple's tolerances for high and low values on the receive pin?  I measured the voltage output from the Edirol UM880 at 5.1V and the MOTU828mk2 at 4.98 V   I'm not sure if this means anything at all 

[Xavier]

Two adjacent messages (Note off, Note on) kill each other.

I'd love to understand that... what do you mean exactly ?
What do you see and what do you hear ?

It might be something to do with the maple's tolerances for high and low values on the receive pin?

Midi is slow. I'm sure the 72Mhz maple can handle it 

I measured the voltage output from the Edirol UM880 at 5.1V and the MOTU828mk2 at 4.98 V   I'm not sure if this means anything at all 

Thanks a lot for testing it... at least the voltage is very close.

Xavier