BUILD & MODs CORE PCB REV 1 - HerrPaule/Euxoloti GitHub Wiki

Here are some necessary explanations to get the Euxoloti Core PCB Rev 1 running. A better and detailed step-by-step instructions was written by FMA from Axoloti Forum. I recommend to use his instruction: https://docs.google.com/document/d/1Rx9O_k-dUJQDzONVk0AzewmyFckbQyXHiNsPy8fmUj8/edit?usp=sharing

Audio In mod:

The two audio input signal are routing to wrong inputs pins of Axoloti. To get it working, don't install any fe/-male Headers.

You can easy drop out the metal jacks at the position which are pre soldered at the euxo core pcb.

And make solder bridge to the neighbor pin.

Vref Diode mod

The LM4040 10V Ref diode is wrong labeled. Please install it like shown on the picture above. Their for, LM4040's NC pin has to be cut away like shown on the picture:

Additional build instructions:

Resistor R41 is not needed. Don't need to install it.
JP1 (with +12V & GND labels) is double named. It's not necessary for final build.
"JP1-AU_FROM_AXO": you can use 90° headers with two crimp connectors like I did or you can directly solder two wires to "JP1-AU_FROM_AXO" and on the other Hand use something like female or crimp connectors to link Axoloti's audio out to Euxoloti.

Before power the Euxoloti core the first time…

…please don't install any ICs or Axoloti core and control pcb. Check each TP with a continuity tester if there isn't any shorts to GND.

If there isn't any short issues, you can turn the power on. Now you should measure:

TP1: +5V Power supply for Axoloti
TP2: max. 3,3V VBusSend pin to enable external external power supply at Axoloti
TP3: -12V from Eurorack
TP4: +12V from Eurorack
TP5: -10V VRef from LM4040 diode

everything fine and no smoke, turn off power and connect the ICs and the Axoloti core. Turn power on and you should measure:

TP6: 3,3V from Axoloti core VDDC
TP7: 3,3V from Axoloti core VDD

Connect the Control PCB to the Core PCB and connect the "JP1-AU_FROM_AXO" to Axoloti's Audio Out pins behind the big audio out jacks. Turn Axoloti on and connect your Host pc/mac to the MicroUSB, start Axoloti App on your Host and start a connection. No errors should be appear at the Axoloti Console.

Audio In calibration

Before you connect any audio source to IN L/R jacks, turn the TR1 and TR2 all the way left to minimize the input volume. Then plugin a loud sound source (any OSC) to IN R. The jack IN R is normalized to IN L if nothing is plugged in to IN L.

Now load and runt the audio-calibration.axp Patch live with your Axoloti.

The two "disp/scope 128 b" shouldn't show any waveform. Now plugin your sound source and turn TR1 slowly right. By turning the Trimmer you will see a Waveform at "disp/scope 128 b". The audio signal shouldn't clip (red color at audio in vuLeft/-Right).
Repeat the process with TR2. The input is inverted by the op amp.

To calibrate the audio output, it's the best to use a Oscilloscope or use any computer audio scope. Then slowly turn the trimmer TR3 and TR4 left to attenuate the signal or right to amplify it.

Next step is, close Axoloti environment, and install the "gate" and "led-button" objects from Github for Axoloti 1.0.6.

Start Axoloti, open and run the 2ADCs-gate-led-button.axp Patch. The cv and pot object should show the values of the two ADCs (Pots and CV In). It's a bit chaotic at the moment. You can find the code for the SPI communication in the "script2" object, just click "edit" button.