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Korg Volca Sample Hack Mod

When I bought my Volca Sample I was disapointed with MIDI implementation – one channel for each track? Ehh? Immediately I grebbed Arduino and made MIDI adapter. Some time later I found mod with switch for mute. Today the cup ran… I added switch for memory too.

MIDI adapter is based on:

Points for solder switches connections – D301, D307 and common point:

Mounting switches:

Mounting Arduino Nano:

USB connector for programming:

DIN connector for alternative MIDI in:

+5V supply for Arduino stolen from capacitor:

All together:

Final look:

e2fsck autostart problem

e2fsck autostart problem

[root@CentOS ~]# cat /etc/e2fsck.conf

# Superblock last mount time is in the future (PR_0_FUTURE_SB_LAST_MOUNT).
0x000031 = {
preen_ok = true
preen_nomessage = true

# Superblock last write time is in the future (PR_0_FUTURE_SB_LAST_WRITE).
0x000032 = {
preen_ok = true
preen_nomessage = true

Install Windows 7 Or Windows 8 From USB Drive

Run command line with admin rights,












D: CD BOOT and hit enter.Where “D” is your DVD drive letter.


BOOTSECT.EXE /NT60 H: – make USB bootable

Finaly copy your Windows 7 or Windows 8 DVD contents to the USB flash drive.

Novation LaunchKey 25 MK2 Arduino USB-MIDI converter



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: 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.


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:


IMG_20180406_230752 IMG_20180406_230351

Alcoma ASD + Wine + USB serial

Pokud potrebujete provozovat ASD Clienta pod linuxem ve Wine, zde je navod:

So, here is what I did to make it work. First of all, unless you want to run Wine each time as root, add yourself to the dialout group, so you can access serial ports without root permissions. This can be done from Terminal:

sudo adduser <your_username> dialout

You should log off and back in for the changes to take effect. This affects not only Wine, but all other Linux application that need serial port access.

The first step is to make the necessary symbolic links. Again, in Terminal:

ln -s /dev/ttyUSB0 ~/.wine/dosdevices/com1
ln -s /dev/ttyS0 ~/.wine/dosdevices/com2

Adapt these commands for your situation. The first one is needed if you use a serial to USB adapter while the second one is for hardware motherboard ports. Add a symbolic link for each of the available serial ports. This command actually gives access to serial ports from Wine. And any Windows software where you can manually edit the serial port will work with only this. However many Windows apps allow user to select a port from a detected ports list. And they will detect nothing in Wine.

Now you need to add a Wine registry key as stated on Strangen0tes blog. Although you could use Wine’s regedit, it is easier to launch a text editor and add the required registry key(s). In Terminal:

gedit ~/.wine/system.reg

What you should add here is not clearly known, so you should try with the following options from Wine Wiki until you find something that works.

This is the common option that works with most applications:

[Hardware\\Devicemap\\Serialcomm] 1231984861

The other one is:

[Hardware\\Devicemap\\Serialcomm] 1131331688

Both worked for me. Yet there may be apps that don’t read this registry key when looking for serial ports.

The association between COMx and /dev/ttyX is made in the symbolic link you made earlier.

APC SMX750I smart UPS external battery pack hack

V siti pouzivame na nekterych bodech UPS od firmy APC konkretne model SMX750I. Vydrz samotne UPS neni nic moc, protoze obsahuje pouze 4ks CSB HR1234W F2, 9Ah, 12V slozenych do 48V akupacku coz je jen nejakych papirovych 432Wh, vzaje v potaz ucinnost UPS a skutecnou kapacitu aku pri vysokych vybijecich proudech, dostaneme se klidne treba jen na pulku. Proto APC dodava k UPS battery packy kde je 8ks (4+2 serio-paralelne) vyse zminenych aku a tedy dalsich 864Wh, coz je stale malo. Proto jsem se rozhodl pripojit k UPS poradnou baterii. Z prvniho zkoumani bylo jasne ze to nebude otazka dvou dratu protoze propojovaci konektor ma 4 piny viz foto.



Proto jsem battery pack otevrel a zjistil schema:


Snadno tedy zjistime ohmetrem, ktery z pomocnych pinu je na kostre a ktery je „informacni“. Je tedy jasne, ze UPS detekuje BP podle odporu na pinu. Pokud pripojime dva originalni BP je vysledny odpor 5k coz je paralelni soucet dvou 10k odporu. Vyrobce uvadi maximalni pocet 5ks ext. battery packu coz je max. vysledna kapacita 4320Wh. Ja jsem koupil 4ks 12V 75Ah baterii coz je 3600Wh coz odpovida 4ks orig. battery packu, proto bud vezmeme 4ks 10k rezistoru a dame je paralelne nebo spocitame ze vysledny odpor je 2.5kohm a pripojime proti minus polu naseho batterypacku a je to.

tabulka hodnot jak to vychazi podle koupeneho akupaku:

1 10k 864Wh 4x18Ah
2 5k 1728Wh 4x36Ah
3 3.33k 2592Wh 4x54Ah
4 2.5k 3456Wh 4x72Ah
5 2k 4320Wh 4x90Ah

Po pridani informacniho odporu 2.5k se odhadovana vydrz zvedla z 30min na 6h

Oprava graficke karty v notebooku Acer Aspire 5920 zapekanim reflow

Pred nekolika dny se mi zastavil OS Windows 7 blue screenem kde stalo ze prestal odpovidat ovladac graf. jadra a konec. Po restartu bylo videt jako kdyby ve framebufferu byly nejake chyby a projevovalo se to ruznymi pravidelnymi poruchami v obraze uz pri startu BIOSu. Abych doplnil celou situaci, stalo se to potom co jsem se nejakou dobu koukal na mjpeg ze dvou kamer a asi to trosku vytizilo GPU/CPU a graf. karta to nejak nedala…

Pokračování textu Oprava graficke karty v notebooku Acer Aspire 5920 zapekanim reflow

Raspberry Pi, 4G LTE modem Huawei K5150 a PPtP client – Public IP pres 4G

Zde budu publikovat své poznatky a tipy, jak zprovoznit na raspi 4G modem K5150 s pomocí USB_modeswitch utilitky a následně zajistit aby raspi drzela zuby nechty pripojeny pptp tunel, díky kterému je raspi dostupná na veřejné adrese a můžu ji nechat kdekoli a dělat s ní cokoliv.

Pokračování textu Raspberry Pi, 4G LTE modem Huawei K5150 a PPtP client – Public IP pres 4G