Just one i2c question to tip me over the egde


My name is Martin Langlie and I’m super close to ordering the ssp:()
Im an enthusiastic er-301 user even though the cpu on the er-301 stops me in my tracks every single time.
My favourite thing to make is instruments that can be played with one or max two faders. I use and love the f8r-module from Michigan synthworks, connecting it via a i2c cable. I know that module have 8 faders, but I’m kind of hung up on super simple controls:)
Patching on eco-mode can be quite inspiring but I dream of being able to make monster-patches that can be controlled with one fader.
I am sorry if this case is closed long ago but my question is this:
Can I connect my f8r-module to the ssp via i2c and start patching?
Greetings from oslo, norway:)


hello again :disguised_face:
im giving this another try to see if anyone knows the answer to this:
Can I connect my michigan synthworks f8r-module to the ssp via i2c?

As far as I am aware, the SSP does not have an i2c connector (not sure what gave you the idea that it would…)
Given that the f8r has 8 cv-outs and the SSP 16(!) cv/audio inputs, 8 short patch cables would do the trick to hook up the two

actually @titaanzink this is factually incorrect - there is I2C!
previous updates, had not enabled it BUT last update enabled it.

I was going to type info here… but decided its better off in the wiki
as it can be updated, and used for future reference.
(a bit longer to do, but hey, building community resources is an important activity !)

Important Note :
I take NO RESPONSIBILITY for this correct of this info etc. Im no hardware professional.
using is entirely at your OWN RISK.

I spoke to Bert about this topic - he was very clear…
Percussa would take no responsibility for any damage caused to the SSP attempting to use I2C on the SSP . so, it’s beyond warranty etc.

which, frankly, is fair enough…
it would be easy to damage the SSP attempting to use I2C… as there are no ‘safeguards’, and it wasn’t designed for ‘end user’ use.

these reasons… and also the fact Ive not ‘tested’ it out yet are why I’ve (and probably Percussa) have not shared this info previously… and mentioned the last update ‘enabled’ it.

(I thought Id share once Ive got around to testing … but its not as simple as just pluging things in… see wiki :wink: )

anyway… In the above WIKI , I not only gives details (as I understand them) , but also detail complications and also ideas Ive had about creating a module to provide i2c (and other abilities)

BUT as I mention, its hard to imagine as an ‘end user’ product, simply due to the investment cost of creating, and also the ‘risk’ that a ‘user error’ could blow up the $2000 SSP module…
its just a gamble thats not worth it.

so whilst I might create for myself, unlikely… it’d go beyond my own use.

Oops :face_with_open_eyes_and_hand_over_mouth: I completely missed that! Apologies @martinlanglie .

From a practical point of view though, if the voltage levels are unprotected and there is no way (yet) to pick up the i2c signals in the core SSP software or through third party plug-ins, I would stick to the CV route (or use MIDI module with CC assignments) to bring external fader signals in.

thank you so much for your time!:slight_smile:
i can see that the risk is unnecessarily big for the average user (me) with no engineering skills and a passion for this to wooork hehe. michigan synthworks also makes this one::
EXP F8R/XVI Eurorack expander: USB C, MIDI, I2C – Michigan Synth Works. they say its “i2c ports are fully buffered for safe i2c connections” dont know if this one is relevant to this case but here it is. thank you @thetechnobear for giving a fantastic creation a heartbeat!

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you’re welcome.

that module, yeah, doesn’t say if its 5v or 3.3v based… Id suspect 5v (*)

also, this module would not solve the master-master issue…
so its kind of the right approach for (eg) connecting SSP → ER301, but wouldn’t work for SSP → Teletype.
(I was mostly interested in connecting a teletype to the SSP … hence my detailed research :slight_smile: )

i2c was never designed for this ‘inter device’ end-user use-case that eurorack has adopted… and frankly its not the right tech ( ** ) … i2c is cool, its pretty fast…
but its a low level, so risky, not designed on-the-go connections , its not a peer-peer connection…has many limitations e.g. short distance connection.

sure, some times its fun to hack things together in unintended ways… but its kind of risky, when you start pushing this as some kind of ‘norm’ for end-users!

don’t get me wrong, I do think there is a need for this tighter connection between modules…
a digital connection, not constrained CV and midi… but i2c is a hack.

really, we should be using i2c for ‘expansion’ modules… perhaps exposing addition IO, if we want a ‘raw’ digital connection, then add a usb3 or RJ45 ethernet connection… which were designed for this purpose :wink:

anyway, it is what it is … and all we have…

as I said, its cool for a DIY project…
and perhaps someone with engineering skills could create a well designed safe expansion module for the SSP…

I think perhaps the most interesting part of this is… with this extra I2C connector, someone like @bert could create expansion modules for the SSP.
although, frankly, I think and i2c bridge module would have limited appeal…

I suspect an output expansion would be really popular with SSP users e.g. a module that added 8 additional cv outputs … even it it was limited to cv (rather than audio) to keep costs down.

of course… as, I mentioned on my wiki post… we do have to consider such a module would have to not only cover the costs of additional hardware, but also the extra cost of module dev on the SSP, and firmware on the module.

if anyone out there is (or knows) a hardware engineer… that would like to collaborate on such a module.
collaboration along the lines of they’d design the hardware ( *** ) , and id write the firmware and ssp module.

( * ) unfortunately the eurorack world seems to consider 5v the standard (as it has a 5v rail) - but reality is outside of eurorack 3.3v is just as common… since many SoC are 3.3v logic.

( ** ) really it only came about because SoC were being used which all have i2c connectors … and some ‘techie’ thought oh, I could connect them with a cheap cable…

( *** ) basically, whilst I know the hardware side to get this tech workmen…
what I really need is someone that can ensure its ‘bullet proof’… so if users connect incorrectly, or plug something in they shouldn’t … then it doesn’t start blowing things up … thats the bit, I really have only vague ideas about.
(oh the other thing to be very careful of, is ensuring it doesn’t introduce noise into the system!)

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I can’t believe how deep a hole of “how does i2c actually work” I just fell into. I can’t help but feel you’re right about this not being ideal for modular, @thetechnobear… but then again, the power isn’t ideal either! :stuck_out_tongue:

yeah, its a slightly complex area… and one that many don’t have a firm grasp on.
we would be much better off with a behind the panel digital protocol based on something more suitable, like usb.

indeed power is also crap, but thats not a good reason to add to our woes !
look at the number of posts about issues with modules, that come down to power related issues (noise, current on-rush) … that many users dont understand…
users believe/expect - “if I have the right voltage and max amp” , it should just work (*)
… and reality is, with a well designed format … it would :wink:

dont get me wrong, in a diy / hacking environment, all is cool… it’s up to the user to work these things out - but they know this is the case.
but eurorack now is completely commercialised, so expectations for the majority are very different.
(and frankly out of line with what the format is capable of delivering !)

(*) but with what they have, they incorrectly blame module manufactures… feeling modules don’t work, to an imaginary spec !

I had one the other day that was as simple as reading a manual and realising this module could be powered from 12v or 5v and I don’t have 5v on my supply. Eurorack is indeed a spaghetti factory with lots of room for innovation (and mistakes) from users as a result. I’d not change a thing haha.