PreenFM Forum

PreenFM => PreenFM1 (the blue one) => Topic started by: fidgit on April 17, 2012, 08:13:32 AM

Title: MIDI on / off issues (1.61) [fixed in 1.70]
Post by: fidgit on April 17, 2012, 08:13:32 AM
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
Title: Re: MIDI on / off issues (1.61)
Post by: 6581punk on April 17, 2012, 09:07:16 AM
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 :)
Title: Re: MIDI on / off issues (1.61)
Post by: fidgit on April 17, 2012, 09:36:12 AM
yes, thank you.
i'll dig into it at the end of the week.
Title: Re: MIDI on / off issues (1.61)
Post by: 6581punk on April 17, 2012, 12:30:47 PM
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.
Title: Re: MIDI on / off issues (1.61)
Post by: Xavier on April 17, 2012, 10:17:33 PM
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
Title: Re: MIDI on / off issues (1.61)
Post by: 6581punk on April 17, 2012, 10:24:29 PM
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?
Title: Re: MIDI on / off issues (1.61)
Post by: funkyfli on May 07, 2012, 06:53:17 PM
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.
Title: Re: MIDI on / off issues (1.61)
Post by: Xavier on May 10, 2012, 02:37:21 PM

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."

Title: Re: MIDI on / off issues (1.61)
Post by: funkyfli on May 10, 2012, 05:06:29 PM
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.
Title: Re: MIDI on / off issues (1.61)
Post by: Xavier on May 13, 2012, 10:49:41 PM
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




Title: Re: MIDI on / off issues (1.61)
Post by: funkyfli on May 15, 2012, 06:03:22 AM
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.
Title: Re: MIDI on / off issues (1.61)
Post by: Xavier on May 15, 2012, 09:13:08 AM
Thanks for having checked... that's really usefull...
If we eliminates the possibilities one by one, we're going to find a solution  ;)
Title: Re: MIDI on / off issues (1.61)
Post by: 6581punk on May 19, 2012, 10:52:44 PM
Can you use the MIDI thru port on one of your devices to send the output to your preen?
Title: Re: MIDI on / off issues (1.61)
Post by: funkyfli on May 20, 2012, 06:58:41 PM
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  :-\
Title: Re: MIDI on / off issues (1.61)
Post by: Xavier on May 20, 2012, 09:28:12 PM
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
Title: Re: MIDI on / off issues (1.61)
Post by: funkyfli on May 21, 2012, 05:04:24 AM
To clarify...
When I line up 2 notes in Sonar the Note Off occurs right before the next Note On.  Neither one gets triggered.  The further apart the notes / messages are, the better they trigger.
By High / Low, I meant the Voltages.  The voltage levels at which the pin goes high or low.  There are different tolerances for different chips.

I hope that triggers an idea :)
thanks,
Martin.
Title: Re: MIDI on / off issues (1.61)
Post by: Xavier on May 21, 2012, 09:32:02 AM
To clarify...
When I line up 2 notes in Sonar the Note Off occurs right before the next Note On.  Neither one gets triggered.  The further apart the notes / messages are, the better they trigger.

OK... and that problem happens only  with the  Edirol UM880 ? right ?

Could you try to set the Release of all envelopes to 0 and check if you still hear the problem ?
Same thing with all the release set to 255.

By High / Low, I meant the Voltages.  The voltage levels at which the pin goes high or low.  There are different tolerances for different chips.

The 6N137 is here to isolate the input, so that the maple always get the same voltage/currant.

Thanks a lot for your help,

Xavier
Title: Re: MIDI on / off issues (1.61)
Post by: funkyfli on May 21, 2012, 07:45:37 PM
Yep.  Just with the UM880.  Setting the releases to 0 or 255 made no difference.

I guess the next step, if you are up for it, is to create a test PreenFM OS that will print the incoming MIDI messages to the screen.  We can then check to see if the synth is receiving correct MIDI messages, bad messages, incomplete messages or no messages at all...  Just an idea.

I should at least switch out R6 for a 180 Ohm as a test...

Martin.
Title: Re: MIDI on / off issues (1.61)
Post by: Xavier on May 22, 2012, 01:54:46 PM

Yes good idea, i'll try to build a OS that output the midi information it receives.

Xavier
Title: Re: MIDI on / off issues (1.61)
Post by: Xavier on May 25, 2012, 02:21:19 PM
Those debug version display on the screen the NoteOn ("O") and NoteOff("F") it receives.
http://xhosxe.free.fr/PreenFM/firmware/DEBUG/

Please Try D4 first in which i have much hope.

D1 is the same as 162.B2.

The D2 version deals with polyphonic after touch, it does not do anything with it, it just consumes the data.

D3 version added... Prevent realtime midi message to change MidiDispatcher state. Please, try this one first...

D4: I implement the running status midi feature... which was missing.  ::)
(http://www.blitter.com/~russtopia/MIDI/~jglatt/tech/midispec/run.htm)


Please let me know what you see on your screen while playing,

If you have time, could you try older firmware 1.60, 1.51 and 1.03 and see if it's better ?
http://xhosxe.free.fr/PreenFM/firmware/

Thanks,

Xavier
Title: Re: MIDI on / off issues (1.61)
Post by: funkyfli on May 26, 2012, 01:36:19 AM
Running Status!  I really should have thought to ask about that one.  So I tried D4 first... disobeying orders :)... and so far it works perfectly!  Next, I tried D3... not so good... lots of W messages. 
So Running Status it was!
Thanks!!!  You rock! etc. :)
Martin
Title: Re: MIDI on / off issues (1.61)
Post by: Xavier on May 26, 2012, 08:03:14 AM
Great...  ;D
Thanks for trying it so quickly.
 
I suspected that so i built a beta 1.62.b3 with this modification.
http://ixox.fr/forum/index.php?topic=21.0
You can install it to have a non-debug working firmware.

I may have broken sysex that's why it's still a beta.
I'll give a deeper try next week and publish an official stable firmware.

Xavier