Since I leave Ableton and switch to HW only setup I needed to make a classic midi out port to my LK. I found solution for older version of LK here: https://www.youtube.com/watch?v=IllVybz_2_8 but it is only for MK1 not for my MK2.

Solution is make USB-host to MIDI converter.

You need Arduino Pro mini and mini USB-host module with MAX3421E. I use library from Oleg Mazurov and Yuuichi Akagawa USB_Host_Shield_2.0 but I had to do little improvement of code because my PID od LK wasn’t in special known devices so LK wasn’t working until my change. Link to my update is below.

!!! IMPORTANT !!!

USB host mini module can’t run at 5V !!!!

USB host mini board doesn’t have 3.3V regulator – that is why I used two step down regulators – first bigger is for 12v>5V only for VBUS – You must scratch path to separate system voltage level from VBUS level – some boards have jumper pads for it but I haven’t. Second step down regulator is for 3.3V to power arduino and USB board itself.

My change is in file usbh_midi.cpp:
/* Setup for well known vendor/device specific configuration */
void USBH_MIDI::setupDeviceSpecific()
{
// Novation
if( vid == 0x1235 ) {
// LaunchPad's endpoint attirbute is interrupt (0x20:S, 0x36:Mini, 0x51:Pro, 0x69:MK2, 0x7b:Launchkey)
if(pid == 0x20 || pid == 0x36 || pid == 0x51 || pid == 0x69 || pid == 0x7b ) {
bTransferTypeMask = 2;
}
}
}
Here is usefull links:

https://www.circuitsathome.com/usb-host-shield-hardware-manual/

https://github.com/felis/USB_Host_Shield_2.0

https://github.com/felis/USB_Host_Shield_2.0/pull/375/commits/71e905e0d8e3985e8e0454bbc6b88cd71b0c5b8b