This will remain my reference unit and is connected to my MIDI keyboard and DAW (Logic Pro).
I know I am late to the party, but I have started to build a second Zynthian unit, which I intend to connect to my Eurorack, using the ZynFace circuitry.
The Euroracks consist of Behringer, Mutable Instruments, Rossum Electro-music, Befaco and Moog modules. I notice from the ZynFace schematics, that the levels are 0-5V for both CV and Gate. While I am sure I can get this to work, it will be limited compared to other MIDI-CV interfaces that I use. The most capable of these is the Befaco MIDI Thing V2 … MIDI THING V2 - Befaco
They used the MCP4728 (like ZynFace) in their first version, but now use the MAX113000, which is an amazingly capable 20 port mixed signal device with integral 12-bit ADC and DAC, which can be assigned to any of the I/O with selectable voltage levels. https://www.analog.com/media/en/technical-documentation/data-sheets/max11300.pdf
Befaco have implemented 0-10V, 0-8V, 0-5V and +/- 5V in their module, which can be programmed for every one of their 12 I/Os.
I would like to propose designing a ZynFace V2, using this device. I can do the schematics, PCB layout and manufacture, but was wondering whether this SPI device could be interfaced to the existing Zynthian V5 architecture? @jofemodo does this seem feasible and would it be something the community would be interested to support. I could write a requirements specification if that helps?
Hi @jofemodo, thanks for the quick reply. Still finding my way around, but I did have a look at the V5 and zynface-v5 schematics. I am planning to design a single Eurorack board which includes Encoders, Audio and CV/gate circuits. I will use the ADS1115 and MCP4728 for the prototype. Will let you know how it goes. Regards KMcA
Hi @jofemodo, forgot to say, I don’t see much user documentation on Zynface, I am assuming that selecting the Zynaptik Input/Outputs and Switches in Webconf configures the Zynface HW.
Zynthian uses I2C for its inter-module communication. We do not currently use the SPI interfaces but we also do not use the pins of GPI 9..11 which provide SPI-0. In theory you could write some code to interface with this interface and build a card that connects to these pins. I would avoid using the SPI-1 because it shares pins with the I2S channels which can be used for audio inputs and outputs.
Hi @riban, thanks for the clarification, good to know that SPI-0 is free. Might be simpler to use a microcontroller like RP2040 to setup/manage the MAX11300 and communicate with Zynthian via I2C?
I would like to do this for all out-board interfaces. Zynthian could offload its i/o to a microcontroller, including switch, encoder, MIDI, CV, etc. I would love to see this in a future build. I did this for the first zynthian I built, using a STM32 Bluepill dev board and wrote a I2C interface. It worked really well and I see merit in revisiting this. There have been reasons why we have not done this but those can mostly now be mitigated.
OK, that sounds like a good plan. I have a couple of MAX11300 evaluation boards and will try hooking them up to an RP2350 board. I am more of a HW guy, but will have a look at controlling the MAX11300 via the SPI port on the pico. You might have to help me out with the I2C interface to Zynthian At least this will allow the board to be connected to the existing EXT-1 expansion connector on the V5 Control board.
At least this will allow the board to be connected to the existing EXT-1 expansion connector on the V5 Control board.