A user's guide to i2c

Sascha · 2022-02-23T15:27:54.019Z

no, you can connect it to teletype or txb. the txb is needed when you use more modules in a chain. he produces pullups

Brennanib · 2022-02-23T17:18:25.231Z

OK to be clear should I plug the expanders into txb or rather straight into TT?

These are all the devices I’m trying to connect together within my case

Teletype
Ansible
White Whale
Meadowphysics
Earthsea
Crow
W/ x2
Just friends x2
Txo
Txi
I2c2midi

Essentially I am asking can I just plug every i2c device into TXb?

Sascha · 2022-02-23T17:27:44.267Z

Yes you can . Thats my Chain

Er301 -ansible -tt -crow -txb

From txb to jf1-jf2 -disting ex -w/1-w2 -txo

All Work stable

IMG_20220218_1758431920×1406 396 KB

Edit : you can only use one Leader in your Chain . And you have to Adress jf to 1and 2
And you can Run different engine with your w/ when you have the 2.0 Beta Firmware on it .when you do it Not all Double modules works together and Not Independently

Brennanib · 2022-02-24T00:50:50.066Z

Ok just didn’t want to power up before asking it was pretty hard to get them all in there right.
(I really need to get longer i2c cables)

Cheers for the help here and lovely system!

Sascha · 2022-02-24T04:48:08.748Z

I have use the "Standard " 20cm jumper cables its enough to get all together .

Do one by one and Check the function .

SimonKirby · 2022-03-23T11:52:56.273Z

Just had to wire the Intellijel XY module up again, so thought I’d give clear instructions here for posterity.

Assuming you’re using the X input on the XY module for i2c, you should wire up the top three pins on the back of the module in the following order:

Top: SCL
Middle: Ground
Bottom: SDA

Also, a cautionary tale to explain why I had to wire it again… I switched on my case and instantly loads of smoke started pouring out of it. I think what had happened was that I was powering my 16n from the USB 1u module, but the magsafe-style usb connecter I was using at the 16n end had come off the socket and had magnetically attached to the metal case of the 16n. I think this had shorted 5v and ground and when I opened up my case I found that one of the i2c jumper cables attached to the teletype (and onwards to my just friends, Ansible, Disting ex) had melted and then caught fire. As you can probably imagine, I assumed the worst and thought no way can any of my modules have survived that amount of current being dumped through them! Miraculously, there was absolutely no damage apart from the melted jumper cable. I’ve no idea how that was possible, but thanking the universe for not destroying all my favourite modules.

Moral of the story… be oh so very careful that everything is connected correctly before turning your case on.

jroo · 2022-04-02T12:14:57.086Z

I currently have Crow, Ansible, Just Friends and W/ working well together but when I try to add any more length or another device it stops working. I assume I’ve hit the limitations of what Crow can power. I could add a Txb or a Teletype into the chain but I’m considering another Crow. If I added another Crow would I be able to add more devices? I guess I’m asking if two Crows means double the power support or if there would be no power advantage to getting another? Thanks.

Sascha · 2022-04-02T14:50:56.416Z

What does ansible in the Chain? Is ansible in leader Mode? Disconect all in ansible and try again . U can only have one Leader in your Chain have you pullups on , in Crow? Jf and w/ Produce his own pullups. do you have all in the newest Firmware?

jroo · 2022-04-02T15:44:03.706Z

After a lot of trial and error I was able to add a Disting EX to the chain but it only works when the pull-up resistor switch on the Disting EX is enabled which is weird because I thought the Crow pull-up had that covered. It’s working consistently now so I think I can rule out a power limitation. I am definitely still curious about whether or not another Crow would allow double the power support on the chain if I decide to add things in the future.

To answer your questions @Sascha, Ansible was leading with a Grid and everything was up to date, yeah. Thanks for thinking about it with me. I enabled pull-ups in Crow via Druid and I assumed they remained enabled across rack reboots but the Disting pull-up behaviour has me confused about that now.

Things seem to work consistently now so I’m not going to rock the boat any more but if someone has an answer to the Crow power question I’d still love to know! Thanks.

nonverbalpoetry · 2022-04-02T16:03:42.821Z

Put very very simply, the more wires you add, the more pull-ups resistors you need. Enabling pull ups on disting would have done the same thing as adding a crow, or adding a txb, it would add more pull ups

doomglue · 2022-04-23T09:46:51.094Z

Two questions, hope this is the correct thread.
And yes, probably one bigger case would solve these questions but I’d like to avoid this as the smaller cases set up cured a lot of my Eurorack pains.
Maybe using patch cables is also a valid answer. Maybe I am a bit too i2c obsessed right now.

First question: connecting i2c modules between different cases:
Any recommendation on how to connect a ER 301 to teletype in another case? I currently am running a 4ms pod with TT, Txo+, Just Friends, i2c2midi and have all the i2c modules on a Txb.
I am thinking that I could just drill a hole in the 4ms pod and connect both cases with a trs 3,5mm cable assuming (solder wires to the jack on the new jack and connect them to the ER301).
Or does this not work? My er301 is a rev7 and I have a Sweet 16 connected right now, which I would then disconnect as it is also a leader.
Maybe I should just stick to using good old cables since I have the TXo+ as well?

Second question:
Would adding a crow be OK to the first case? Can you run norns crow scripts with Just Friends?
How well does Crow work with TT by now?

Gerald_Stevens · 2022-04-30T20:32:04.632Z

I think the i2c world would greatly benefit from a 4HP 2-bus switchable version of TXB. Was going to build one of these into a i2c2midi, which had all that panel space, but then the 2HP mkii version dropped. I’m thinking that it has 4-6 slightly recessed 2P2T (SCL/SDA) slider switches that allow you to switch between two separate busses. Of course, you should not hot-switch i2c, so the ‘recessed’ switches should be used only while the power is off - maybe find red switches or keep them back far enough from the panel that you need a pen to slide them. This would solve my (and many other’s) problems with too many leaders (Ansible, teletype, and distingEX just cannot seem to co-exist in the same space-time-continuum). Maybe I’d just use the switches for leaders - and keep all the followers on a separate bus. I’m bringing this up so that others can chime in about desired functionality. Or even better - someone more current in their Eagle skills could whip this up - TXB mkii @bpcmusic ? @Pusherman ?

sixolet · 2022-04-30T20:36:56.666Z

You would have to not switch while power is on, right?

Gerald_Stevens · 2022-04-30T21:06:51.107Z

That’s why the switches would be recessed and red. I looked it up, and it doesn’t look dangerous to hot-switch, just likely to cause things to latch-up. I know this sounds scary - but TXB has a stereo jack on it - hot-swapping with that can short out all the contacts, and yeah, that’s not good. But people haven’t been writing in that their 16n burned out their bus, so maybe it is OK?

sixolet · 2022-04-30T21:11:36.907Z

Ok yeah that makes sense. Certainly hitting a recessed button between power cycles is easier than re-wiring

bpcmusic · 2022-05-01T15:54:42.888Z

I’d be careful with those i2c lines; I’ve fried a microcontroller in an expensive module fussing around with them. Only connect things when stuff is off and triple-check before turning things back on. While you may be able to fly fast and loose sometimes, the one time it gets you will really suck. Trust me. (I2C is not USB.)

For this reason, I keep neoprene plugs (way better than the 3D printed ones I tried back in the day) in the jacks on the TXb to avoid any module-killing disasters … which are easy to create when doing late-night patching.

Scenarios like this are why there are 2 jacks on the thing, btw. I’ve successfully used it to re-patch configurations (when the gear is off). A couple of TXb units and some short stereo cables can give you some nice flexibility.

That all said, I still kinda regret using the same jack size as Eurorack interconnects. I looked for other connectors that would have avoided the chance of an “errant patch of death” - but there just weren’t any good solutions. That, and the use of the jack on the 16n, made it a begrudging compromise.

Finally, I won’t have the time (or the stomach) to do anything with switches. I’d looked into it back in the day as a solution, wanting something similar, and just didn’t feel good committing more sins against the i2c gods. Good luck!

Gerald_Stevens · 2022-05-04T22:49:00.804Z

Thanks for the Sage advice. Those late-night rack-stuffing sins are what the switches might avoid. I also am sensitive to building something that will one day lead to someone frying a nearly irreplaceable Just Friends. I ended up buying a bunch of ribbon cable and 2x3 crimp connectors to keep all my I2C on the back of the TXb locked down nicely. But I’m still stuck with the fact that two leaders (even though Ansible should be following on boot-up) seems to hose my disting-EX follower. Maybe two TXb’s and a jumper is a good way to go - especially since I have a pair. And I have these really cute Teenage Engineering 4" stereo jumpers.

sixolet · 2022-05-07T06:21:16.056Z

The order of things on the bus doesn’t really matter in a technical way — put them in an order you find aesthetically pleasing, easy to use, and and easy to wire.

brick · 2022-05-07T18:57:35.719Z

So I’ve recently got a Crow and I’ve found myself wanting for a couple more inputs for CV to modulate scripts. In my searching, I found this guy from Expert Sleepers; seems to just be 8 jacks that can be set up as inputs or outputs, to be accessed over i2c.

Anybody have any experience with this? Especially since I can’t find any Telex modules available these days, and just want some extra inputs.

3-foot-1 · 2022-06-04T20:01:18.148Z

I was wondering if one of the electronics-savvy members could comment on exactly how and why hot plugging a TRS/i2c plug is dangerous. Recently there was some conversation in the Teletype discord about alternate plug designs and it got me wondering what is possible in the context of the current TRS semi-standard for connecting i2c busses in different cases.

For example, given two TXb modules in two cases:

If you had an empty MIDI TRS-DIN adapter plugged into each TXb before you turned the cases on, could you safely connect them afterwards with a MIDI DIN cable?
Is it dangerous to plug an unconnected TRS cable into the TXb when it is on? (If so, which are the pins that get shorted?)
Would hot plugging be safe if the connector order were different? (For instance, what if GND were ring instead of sleeve?)