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Messages - Xavier

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PreenFM2 / Re: 3 note max polyphony????
« on: July 02, 2017, 11:20:02 AM »

The max number of voice for one instruments depends on how many voices are allocated by other instruments.
Set I2, I3, I4 voices to 0.
Save the default combo  Menu>Save>Defl>Save
Than you'll get the max number for your I1. Up to 14 if your I1 algorithm uses 3 operators.


PreenFM2 / Re: MIDI messages question
« on: June 21, 2017, 09:14:15 PM »

For all NRPN floating point params : the forumla is :
Code: [Select]
            valueToSend = (floatValue - param->minValue) * 100.0f + .1f ; // minValue if the minimal value authorized for the param (-1.0; 0.0...).
            cc.value[0] = 6;
            cc.value[1] = (unsigned char) (valueToSend >> 7);
            sendMidiCCOut(&cc, false);
            cc.value[0] = 38;
            cc.value[1] = (unsigned char) (valueToSend & 127);
            sendMidiCCOut(&cc, false);

IF the minimal value of the param is 0.0 which is the case for ADSR.
The NRPN 14 bits value is the time in 1/100th of seconds.

If you use CC you cannot send all values :
The param will be value/64 in sec for A, and /32 for R.


PreenFM2 / Re: MIDI messages question
« on: June 14, 2017, 09:12:32 AM »
Thanks a lot for your message. I fixed the errors.

LFO <n> : NRPN LSB should use (n-1) in the formula instead of n.

Let me know if you find other errors.


PreenFM2 / Re: Harsh noise at 13,5kHz from preenFM2
« on: June 11, 2017, 08:17:40 AM »
Does this noise happen with all PCB versions?  Does it happen with R5c?

I just realised there was an PCB version error in the link above. I wrote R4 instead of R5.
Should be clearer now:

The noise come from the yellow OLED display so 'yes'.
With R5c the shield modification is doable but more complicated than with the R5d.
A safe way to avoid the problem is to use a LCD display (unfortunately not compatible with the metal case).

I learnt recently that some web site sells the R5c version   :-\

PreenFM2 / Re: PreenFM2 in recordings ;)
« on: June 05, 2017, 11:09:29 AM »

The track preen1bank2 is very very nice:

PreenFM2 / Re: PreenFM2 in recordings ;)
« on: June 05, 2017, 11:02:33 AM »

Fantastic work..  8)
I just shared this on the facebook preenfm site. It has more visibility than this forum  ;)
Thanks a lot for sharing here.


PreenFM2 / Re: Bought used preenfm2, usb not working properly
« on: May 29, 2017, 08:42:38 PM »
Thanks for the tips Xavier. I will try to follow your tips and let you know. I do not know what CPU board I have and also the PCB revision! :) How can I discover? thanks and sorry for the "newbiness" ;)

Can you attach a picture of the whole PCB ?

The PCB revision is written on it : something like "R5d ".

For the CPU board this is the preenF405 :
And this is the CERB40 :

And don't forget to upgrade your firmware. 2.07 is the latest revision and your preenfm2 will be much more powerfull with it than it is today with the 1.06.


PreenFM2 / Re: Bought used preenfm2, usb not working properly
« on: May 28, 2017, 05:57:53 PM »

What CPU board do you have? preenF405 or CERB40 ?
What is your PCB revision  ?

I would say you have a CERB40 with a faulty internal USB cable or without cable at all.
For more information about this cable, search for CERB40 in this page :



PreenFM2 / Re: Feature request?
« on: May 16, 2017, 09:37:33 AM »

Nice to read you enjoy your preenfm2  :)
I never know how to answer to question that begins by "is it possible"....
Do you ask (1) if it's possible, (2) if it's easy to do, or (3) if i would plan to do it ?

1 - Yes it's possible, the firmware is open source.
The midi to audio conversion is done here :
So you have to modify the code to introduce a delay at this point. Requires a little research to do that.
Then the timers for each instrument must be added somewhere in the settings.
2 - Not very easy
3 - No. It will add some complexity in the menus and settings that is not worth it to my opinion.

Possible Alternative : for the instrument you want to introduce a delay
. Set all mix* params to 0.00
. Set a matrix row like this : env2 1.0 mix*
. Then select the modulation : "Free Env 2" like this : "<D> 0.00 5.0 No"
Where <D> is the delay before your sound will begin.

Pseudo delay effect : can be done by
. using one LFO to pan the sound in the matrix (lfo1 1.0 pan*)
. And the gate target matrix (with an other LFO twice faster) to make the sound hearable only when right or left.

PreenFM2 / Re: Output volume vs polyphony..
« on: May 16, 2017, 09:18:44 AM »

This is how it works.
The voice mixer is 100% digital.

So it maximizes the number of actual bits for each used voice.
Same thing : instrument not used should have their number of voice set to 0 so that it does not take any room in the digital mixer.

Summary : for best resolution, only set the number of voices you really need for each instrument.

PreenFM2 / Re: Can't save to usb
« on: May 15, 2017, 10:48:59 AM »
Thanks for the details (i've modified your subjet).
Sounds like a bug.
Don't know if it's easily fixable as the USB library is the one from STM (the MCU manufacturer).

PreenFM2 / Re: A higher polyphony ??
« on: May 15, 2017, 10:30:52 AM »

What you describe is of course possible, but it's a LOT of work.
No i won't work on that  ;)

You can chain 2 preenfm2. But they'll have to play different instrument.
Polyphony on one instrument cannot be expanded.


PreenFM2 / Re: Stm32F4Discovery port
« on: May 11, 2017, 03:45:36 PM »
Hi Xavier!

Thanks for the tip. I just checked the symbol list, and found, that at 08041AC0 there is the OTG_FS IRQ handler, and thought that the 0x28041AC0 dumped PC value can be the same with a memory mapping offset. I'll try to find it with gdb, though I only used it before to debug a connected target.

Yes RAM adress in the STM32F4 is 0x20000000. So this is the same adress moved into MCU RAM !

PreenFM2 / Re: Harsh noise at 13,5kHz from preenFM2
« on: May 11, 2017, 03:40:37 PM »

Yes this come from the yellow OLED display.
Verify your PCB version and read carefully this :


PreenFM2 / Re: Stm32F4Discovery port
« on: May 11, 2017, 09:38:27 AM »
The goal of this register dump is to be able to find where the firmware crashed.
I'm away from my dev computer and I don't remember exacly the steps to debug.
The PC (program counter) value is where it crashed.

With a mix of gdb, elf binary, 'layout split' or asm, and a gdb function to go to the PC value, you should get the C++ line where it crashed.

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