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Messages - Xavier

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PreenFM2 / Re: Simulating Karplus Strong with PreenFM2
« on: May 08, 2017, 05:27:48 PM »

Thanks a lot to take the time to share what you've found  :D

PreenFM2 / Re: Can't save to usb
« on: May 08, 2017, 05:17:31 PM »
Could you describe with more details what you're exactly doing ?

PreenFM2 / Re: Connecting..
« on: May 04, 2017, 10:53:47 PM »

First verify you have JMP1 shorted. But if the 7805 is hot i assume it's OK.

I verified and saw you have a kit with a LCD display.
Is the LCD brighter when you switch on the preenfm ?
Have you tried to turn the contrast pot ?

Then check the different voltage as shown in the message #6 of this thread :


PreenFM2 / Re: Connecting..
« on: May 03, 2017, 09:22:28 PM »

9V, + at the center, should work.
That's strange.
Check that your power supply does not provide more than that.
The 7805 is hot, but that should not be a problem.
Reverse polarity should be blocked by the diode D2.

But smoke is a problem ! Maybe a cap in the wrong polarity ?

Midi polarity is important and is explained here :

PreenFM2 / Re: New slippers -> no USB
« on: May 03, 2017, 05:28:13 PM »
Did you check the external USB solder joins on the main PCB ?

You can order a preenF405 from the shop.
It should be compatible with your white PCB (check it's a R5 version) and you won't need a internal USB cable.
I'll get it back and reimbourse you if that does not fix anything.

PreenFM2 / Re: New PreenFM2 user, old PreenFM2
« on: May 03, 2017, 05:23:41 PM »

Have you tried with a standalone USB power supply such as one for tablet/smartphone ?
Or with a 9V power supply ?

You can plug directly a headset to one of the audio output to check the sound quality.

PreenFM2 / Re: New slippers -> no USB
« on: May 02, 2017, 11:59:58 AM »
OK it's a CERB40.
Seems like there's a problem with the internal mini USB cable....

Can you post a picture of your PCB + CERB40 inserted ?

PreenFM2 / Re: New slippers -> no USB
« on: April 30, 2017, 10:22:22 PM »

First check that it's not just a problem of setting that have been reset.
Is the USB over midi enabled ?
Read part 3 here :
(But as you say USB stick is not visible through the boot loader mode, i doubt...).

Look at the schema in this thread
and check the external USB is still connected to the pin 38 and 39 of the preenF405... (I assume you have a preenF405 and not a CERB40 MCU board)

There's no USB specific chip, USB devices are integrated in the main MCU (microcontroller unit / stm32F4)
There are 2 : 1 for the external USB and one for the USB stick.
I never saw a broken USB on a working MCU.
If that appears to be the case, then you have to change the whole preenF405.


PreenFM2 / Re: New PreenFM2 user, old PreenFM2
« on: April 29, 2017, 10:04:15 AM »
Hi Sammy,

Firmware 1.B7 ? Ouch !
Flashing the firmware is the first thing you should do.
Download latest firmware 2.07, put it on the USB stick (can be done without opening it with firmware 1.10) and flash it.
It's explained here :

The very first version of the preenfm2 had a volume that can be noisy when you turn it.

Do you power it through USB ?
If yes, try an other one, some are noisy.


PreenFM2 / Re: Keyboard scaling on envelope rates..
« on: April 26, 2017, 03:58:53 PM »

Hi Thierry,

There is a "Dec*" destination for "all enveloppe decay" available since firmware 2.05.

Are you talking about something else ?

PreenFM2 / Re: FareyPreenFM2 little programming tool
« on: April 18, 2017, 05:22:30 PM »
Thanks a lot to share this.
Very interesting reading and tool !

And of course glad to read you enjoy your preenfm2 :)


PreenFM2 / Re: USB is only good for power supply
« on: April 15, 2017, 12:37:02 PM »

I thought it was only used to flash the bootloader....

I have many of this DIY mini USB connectors, PM me if you need one.

PreenFM2 / Re: USB is only good for power supply
« on: April 13, 2017, 05:15:45 PM »
I built it and flashed its bootloader to v1.11 a few months ago with the mini-usb.

I just realized you wrote "Mini-USB" ?
So you have a CERB40 cpu board ?

You need a wire to link the case USB to the CERB40 mini USB.
Search for CERB40 in this old-PCB page :

PreenFM2 / Re: possibility of obtaining a new pcb? or schematic?
« on: April 12, 2017, 11:07:28 AM »
actually it was xavier (as usual) that posted the right schematic. i was just doing stupid copying of a GitHub link. :-)

You made me realize i still haven't put the real PCB on github  ;)

PreenFM2 / Re: USB is only good for power supply
« on: April 12, 2017, 10:11:39 AM »


Is the USB midi enabled ?
See 3.1 here, first setting :


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