Author Topic: FAQ  (Read 34119 times)


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« on: January 01, 2014, 03:50:24 PM »
Why isn't <Awesome feature> supported ?
Can you add <Awesome feature> to the firmware ?

Let's discuss that on the forum.
But before, keep in mind that:
The preenfm firmware is open source and anyone with dev skills, can fork the git repo and make all the modification they want.
I'm always very happy to give code information and explain how things works.
For the official firmware i add what it think are the most valuable for majority of users, and also try to follow my vision of this synth.
(The amount of free time i have has also a big impact on that)

Where can i find FM documentation ?

Forum member "fori" recently post this list

Where are the last firmwares or other files to download

preenfm2 :
preenfm3 :

The encoders does not respond correctly

If you need 2 ticks to increase by one the value or if one tick increases by 2 the values, you need to change the encoder drivers.
In the menu (Menu > tools > set > "Rot. enc.") you can chose between 2 encoder drivers: 12 and 24.

How do i enter the bootloader

Press any key when turning on the preenfm2.
Press the menu key when turning on the preenfm3.


SD card Error #-6# with the preenfm3

See this thread


My display remains black when i turn on the preenfm2

Check that you removed the jumper JMP3, and turn it off and on again.

The Midi over USB does not work / The Led is not flashing on midi clock beat

Must be enable in the settings.

Can i access USB drive without opening my PreenFM2

Yes you need bootloader 1.10+
The PreenFM2 registers to your computer as a mass storage and redirect all low level access to the USB stick.
Don't expect high bandwidth, but it works :-)

What are P1, P2 and P3 for ?

. P1 allows you to plug a st-link v2 debugger.
. P2 extension port  (removed from PCB R5)
. P3 analog input. CV you need the adcIn branch of the github repository :

Except P1, none of them is useful today, and i cannot guarantee they will be useful someday.

TroubleShooting / It does not work

You can start by reading this thread :
And verify the different points shown of message #6.
« Last Edit: May 15, 2023, 02:30:28 PM by Xavier »