Zynthian V5 Eurorack

[KMcA]

@jofemodo Can you please help with this configuration issue?

I am using the latest Vangelis Beta

Zynthian Rack CAD 2026-08-061920×1427 291 KB

I have made Eurorack version of Zynthian V5, it uses a RPi Touch 7" display, RPi5 and a custom PCB with combined V5 architecture Encoder/MIDI/Audio, together with Zynface CV/Gates and Eurorack power rails. This will fit into a 64HP Eurorack.

Zynthian Rack1920×1003 500 KB

I am testing the first board using the ‘Custom’ setting in WebConf… Encoders, MIDI and Audio all work and it sounds great

However, when I enable the CV/Gate circuit, using the Zynface-V5 (16Xdio+4Xad+4Xda) config, the Gate outputs are floating, which suggests it is not correctly configured.

I also get the following error in the UI log on startup: ZynCore: write_pin_zynmcp23017(0) => invalid pin!

If I use the ‘V5 Zynface’ wiring layout, I get the Vangelis Error screen … Setting Audio to ‘dummy’ fixes this , but the CV/Gate inputs and outputs all work correctly.

The I2C devices are correctly read as follows:

I2C Scan 2026-08-041096×464 16.8 KB

So the hardware appears to be working, but the zynthian_envars.sh files are different between ‘custom’ and ‘V5 Zynface’ configs

CUSTOM:
ZYNAPTIK INTA = WPi GPIO 5
ZYNAPTIK INTB = WPi GPIO 4

V5_ZYNFACE:
ZYNAPTIK INTA = BCM24
ZYNAPTIK INTB = BCM23
ZYNAPTIK base pins = 400–415

It seems like the ‘custom’ config is not setting the correct Zynaptik interrupts and giving the ZynCore: write_pin_zynmcp23017(0) => invalid pin! error

I would like to understand how to create a Wiring layout for this board which will boot consistently and make sure the MCPs have the correct addresses and interrupts assigned. Can you help?

Thanks in advance.

[KMcA]

OK, so after spending a few hours with ChatGPT, I managed to trace the issues.

It appears that the ‘Custom’ wiring layout does not pass the correct interrupt pins for the Zynaptik MCP23017 to Zyncore, this gave the UI error ZynCore: write_pin_zynmcp23017(0) => invalid pin!

The ‘V5 Zynface’ wiring layout hardwires the correct interrupt pins and ignores Webconf.

However, when I selected the ‘V5 Zynface’ wiring layout, the Zynaptik circuit would work correctly but gave me a Vangelis Error screen when I enabled ‘V5 Adac’ audio.

This was different problem and was traced to a clash loading then attempting to reload the TPA6130 (Headphone) driver, but failing.

The ‘V5 Zynface’ and ‘V5 Adac’ configuration was correct, but the Zyncoder binary I was using was built with the wrong TPA6130 driver choice.

Simply doing a System Update from Webconf with the following settings corrected the problem

So finally the all-in-one Zynthian Rack board boots reliably and is working perfectly; Encoders, MIDI, Audio and CV/gates

I am now going to finish the Eurorack panel and make some improvements to PCB.

If anyone is interested in the CAD files let me know.

[jofemodo]

Hey!! These are really good news, @KMcA !
I’m really sorry for not having being more helpful with this. Please, don’t think for a moment i’m not interested on your progress. I’m simply too busy with the “spanish summer” and the little work time i have, i try to be focused in Vangelis issues.

I will try to take a look and fix the Zynaptik configuration. If you could open a ticket in the issue tracker, it would help to avoid this get forgotten.

The best,