Arduino Portenta Eurorack Shield

[amyodov]

For quite some time, I have been thinking... is there such a thing already? Could someone build and start selling that? I was even thinking of designing that myself, but my own radio/PCB design skills are sub-sub-part. I would write something for it though...

Such an “Eurotenta” should be a shield, not “having a ready Arduino soldered in” (like ARDURACK does?), so it becomes upgradeable (we already have H7 and X8). Also, to decrease the cost of the board/shield itself, so no need to include a specific one. And they would use those Portenta’s 80-pin high-density connectors.

“Eurorack”, so this shield would already have some knobs and jacks mapped to the DACs/ADCs. Also, a USB-C port on the front panel, and even an Ethernet jack too (Portentas support it).

For the ultimate modularity, some potential future expansions can be planned, to add more niched Arduino-compatible addons to this base. I think that the “high-density connector” supports 3 16-bit DACs but also 8 ADCs, 4 PWM modulators, 7 GPIO... even 2 USB connectors. So this base board could even have a separate flying-bus expansion for extra modules, if you need more knobs and inputs/outputs. Or more USBs. Or even a tiny display, I think, via SPI...

So you get such a “Eurotenta” board. You buy a matching Portenta (H7, which is already rather powerful; X8 if you are into some extreme performance). You just plug it in. And voila, you have a Eurorack module, which you can plug in some regular Eurorack in/out jacks,... but write any logic as for a regular Arduino.
And suddenly, you have a very, very large power in your rack. ARM 480 MHZ + 240 MHz for H7; 9 cores for X8. Enough RAM and Flash memory. Wifi and Bluetooth support. All of that controlled from your code, which is as simple to create/share as any Arduino software. You even have the Ethernet expansion... so such a module can be a cool audio DSP; an bridge to plug your Bluetooth controller into Eurorack; an AES67 or AVB bridge into Eurorack (or even Dante?); an USB-to-CV converter; recorder/player of CV sequences to MicroSD card... maybe, even all of these functionalities at the same time.

Anyone has any ideas, is it feasible to design such a shield PCB?

[whyterabbyt]

So its not actually a thing that exists, just an all-singing all-dancing thing you want someone else to build?

[amyodov]

It's a request-for-comments, mostly, a shared brainstorming session.
And, instead of “all-singing all-dancing” – such a thing is very specific, very concrete in its core. And very doable by anyone with some understanding of electronics and Eurorack DIY.
2 80-pin connectors. Power conversion from the Eurorack bus. Several 3.5mm sockets, with overvoltage protection (optionally: dip-switch-configurable to be either –5-to-+5 V or 0-to-+10V) and output-to-output protection, connected to Arduino’s ADC/DACs with voltage range conversion (Arduino is 0 to 3.3V I think). Optionally, several knobs which can control the inputs/ADC values if there is no signal in the according socket. USB socket(s), (and, optionally) RJ-45 socket. Some mechanical way to place the antenna, connected to Arduino itself (for BT/WiFi capabilities). (Very optionally) Some way for future expansion, because the 80-pin connectors clearly support much more knobs and features than makes sense to put in the base shield.
Everything looks very doable and straightforward, isn't it? So straightforward I am tempted to try investigating how to design/build such thing myself, to be able to program some very powerful DSP, even though the last time I have been holding a soldering gun, was around 20 years ago.
Anyone knows some good resources/hints/guides on designing the ideas mentioned above? (Such as, voltage range conversion or all those voltage/power protections).

[PieBerger]

Following, as this might be a fun project to tackle, if/when I further my electronics knowledge. I'v been building DIY Eurorack modules for a while now, so I'm pretty competent on the assembly side, but I still don't fully understand the fundamentals of electronics, to a degree that I could confidently design anything myself from scratch or create a kind of frankenstein circuit from components of similar open source circuits, e.g. Ornament & Crime.

I do have a little bit of knowledge that I can impart, to help you on your way, should you decide to give it a go Regarding power conversion from the +/-12v Eurorack standard, you could do this with a DC/DC converter (more expensive, but more stable) or using a shunt voltage regulator (e.g. LM4040) which is cheaper and a bit less stable, but good enough for Eurorack; it's the method used for providing 3.3v to the Teensy on the Ornament & Crime module and it's also used in a few modules I've built for their 5v sources.

For over voltage protection, you can use Zener Diodes. I'm not sure what the max ratings are on the Portenta but if it's 5v, you would like want to use 5.1v Zeners. You can use the search engine of choice to lookup "over voltage Zener diodes", for further information on how to implement in a circuit.

[imrae]

Daisy Patch submodule is really good and the pricing seems fair.

[sin night]

A Portenta H7 is not exactly "cheap"... it's affordable, but not in no-brainer territory like an Arduino Uno/Nano; I also guess a shield with the features listed by the thread starter (for example 16 bit DAC... but the H7 has only 2 12bit DAC, if I didn't misread the specs on the official website; so it would require some additional chips) won't be exactly cheap and/or straightforward.

It doesn't look as something to just fool around and learn something; the price and computing power would be probably geared towards people who have very specific needs and already know what they are doing (also coding-wise... and have enough time to code!). How big could be the market for such a shield? And how much could it cost to the final user?

Also, another consideration: I'd also desire a dedicated software library if there's some additional chips on the shield, in order to reduce the amount of work required to use the I/O (for example, I'd like something to just send a value / stream to the 16 bit DACs, if they were among the board features), so I could focus on logic/dsp instead of dealing with low-level details. That would be part of the shield price, of course (but it could also make the potential audience slightly larger).


Finally, unless I'm missing something, all that computing power and connectivity seems required only for complex projects, likely involving DSP... something simple like a LFO could be built with just an Arduino Nano, like this one [url=https://note.com/solder_state/n/n4c600f2431c3]link[url], for a fraction of price (I actually plan to build one soon, to integrate it in a filter box).


Why should someone develop a really niche shield, unless it's a labour of love (or multiple shields are needed for several projects, so the development makes sense)? It doesn't even seem a quick and straightforward project to me (by the way I'm not an electronic engineer, I come from an IT background - which is also my dayjob - and I play around with electronics in my free time, but just enough to buld some music tools that I want)...


Maybe I'm over critical, but I have a gut feeling that I probably wouldn't want to work on something like that...