A user's guide to i2c

scanner_darkly · 2019-07-07T18:30:31.149Z

pull-up resistors must be provided by at least one device. i’m not sure teletype alone provides that. the backpack will, however.

with everything connected, are you able to send i2c from teletype to er-301? if it works, the next thing to try is update 16n with leader firmware and see if it can send to er-301 directly (you will still need to have backpack connected for pull-ups, just don’t send anything from teletype at the same time as multiple leaders are not supported).

no, the leader/follower are two different firmwares. pull-up resistors don’t control the mode, they just provide the hardware needed by i2c.

claasp · 2019-07-07T18:53:49.074Z

iwith everything connected i can send i2c from the tt to the er301 yes.

oh i see i was under the impression that the fb could be loaded with the follower firmware and communicate through the tt to the 301.

scanner_darkly:

no, the leader/follower are two different firmwares. pull-up resistors don’t control the mode, they just provide the hardware needed by i2c

makes sense thanks for clearing that up.

scanner_darkly · 2019-07-07T19:17:50.381Z

yes, 16n can be loaded with either the leader or the follower firmware. teletype can only poll values from 16n when 16n is running the follower firmware, and you can only send directly from 16n to er-301 when it’s running the leader firmware. in the setup when you have both teletype and 16n connected to er-301 you want 16n to run the follower firmware (as multi leader setup is not supported), and then you use teletype to poll 16n values and pass them to er-301.

instructions on how to load 16n firmware should be in the 16n thread.

okyeron · 2019-07-19T18:47:36.148Z

I’m not familiar with the Jetson Nano so not sure I can offer much specific advice on it’s setup. That being said, problems usually come down to either leader/follower settings, addresses being set correctly or device startup order.

What other devices are you working with here? Which device is set to be leader?

atomboyd · 2019-07-20T04:54:53.963Z

Stumbled upon a nice video with little snippets that firmed up a a little of the blurry edges for me on a few things i2c related and thought I’d share:

Fun fact: hadn’t realized that It’s “I squared C” (eye squared see?), not “i two c”.

toomanatees · 2019-08-16T14:24:59.128Z

This post in lunchbox case thread:

42/54 hp Lunchbox Inspiration Equipment

I should mention that the TRS MIDI jack on the Palette case is just a pass through connector to a header on the PSU (meant for uMIDI 1U)… you could wire this to the i2c on the back of the ER-301, and then to your fader bank. Is untested, but should work.

sparked my curiosity about using the palette cases to hook up faderbank i2c to teletype. It looks like internally the midi jack is passed through to a 10 pin connector on the psu. So theoretically I need a 10 pin to i2c cable? How would that work? I’m definitely green when it comes to this stuff, and not even really sure where to start looking. This seems like a decent use case for the trs-midi in the palette cases so it would be nice to see it documented somewhere.

slowwild · 2019-08-16T15:39:40.872Z

Here’s the mapping for the internal connector to the TRS jack on the Intellijel Palette case

trs-map-intellijel-palette-case

You could just use a 3 strand jumper cable with separate ends (like below, but just 3), or 3 separate jumper wires.

12796-00__35381.jpg600×600 105 KB

toomanatees · 2019-08-16T15:47:45.120Z

Thank you! Such a simple solution. Excited to try this out.

tehn · 2019-09-08T16:12:46.925Z

re: TXb

okyeron:

Be extra careful to not accidentally plug a regular CV into an i2c input - doing so can damage your modules!

i’m absolutely not suggesting someone do this, but has anyone blown up their modules putting 10V into the i2c lines?

it seems like a very dangerous accidental plug-point. in past research i found some i2c hotswap ic’s, but i’m not sure they protected against big voltage. it might be worth collectively putting some time into creating a schematic solution for 3.5mm stereo i2c protection— which should be on all devices (ie, TXn and 16n and case-jumpers, etc)

okyeron · 2019-09-08T17:14:46.132Z

16n has a bunch of diodes around the i2c pull-ups - and I’ve not actually paid attention to if those are there to prevent this problem. @infovore can you confirm?

infovore · 2019-09-08T18:02:13.033Z

Yep, on 16n, D1-D4 are clamps between GND and 3V3 to avoid anything higher than 3V3 (or lower than 0V) on the I2C lines. I think I copied these from @bpcmusic’s schematics for TxX, etc, or maybe I remembered to do it. But yeah, the diodes are kinda mandatory, and for exactly this purpose.

Julian_Edwardes · 2019-10-03T09:57:32.286Z

Hello, I’m having some i2c issues and hope someone can help out I have Ansible, Txo, Txi, W/, Just Friends, and ER 301 wired to TT through a busboard.
I also made this stereo minijack chassis in 2hp to connect 16n faderbank to the busboard. Sometimes TT freezes forcing reboot. Or if I try to call a Ti.param or FB 1 TT freezes. It doesn’t happen all the time but occasionally.
Also experienced that TT won’t boot, I turned down power and removed the 16n jack, then TT will boot.
This one time TT freezed I slightly touched the mini usb of the faderbank and TT came back alive… Is this some ground issue perhaps? ( Faderbank has no issues sending voltage from the jacks )
What am I doing wrong? Is daisy chaining advisable in this setup for instance? Cable lengths are short but it’s crowded back there. This setup worked pretty well for quite some time… Any help is appreciated thanks in advance

EqualTemperament · 2019-10-03T13:33:31.757Z

What has changed since it worked well?

Julian_Edwardes · 2019-10-03T15:54:14.031Z

That’s just it, nothing really… I have had some issues with the faderbank before though…replaced the i2c cable and it worked fine after that… But today this TT freeze came up while polling a TI.PARAM, never had that before and 16n was not connected so the glitch came from elsewhere

EqualTemperament · 2019-10-03T16:29:36.908Z

So it sounds like without 16n, everything works fine? Is 16n on the leader or follower firmware? How about ansible? Did you load the latest firmware? Is it by chance in leader mode?

Personally I have everything on one bus, some connected to Teletype backpack, others daisy chained. Same devices as you minus the mannequins devices.

Julian_Edwardes · 2019-10-03T16:36:25.476Z

16n is a follower, no pull ups were soldered. Ansible is up to date and is also a follower, I can call Arc (Levels / Cycles etc…) on the TT… I also thought that 16n must be the issue but then I had some trouble with TXi… I’m afraid I have to start with one connection and work my way up to find the issue…will also try daisy chaining. The stereo jack chassis might be glitchy for 16n, then again, it’s just three wires right? Have you ever experienced a TT freeze due to i2c issues Joe?

EqualTemperament · 2019-10-03T16:49:16.584Z

Not as of yet. Even with multiple leaders Teletype has never frozen on me.

Julian_Edwardes · 2019-10-03T17:28:29.928Z

I think I’ve found the problem, I changed power adapters and usb cable for the 16n and things seem stable… What’s puzzling me is that I checked midi through usb on my laptop and midi monitor read the faderbank correctly… This cable/ adapter however seems to disturb the i2c lines in the modular system?

okyeron · 2019-10-03T17:38:45.218Z

Perhaps the usb connector on that cable was not getting a solid enough connection? Or was intermittent in some way that caused the i2c bus some issues.

#1 Teensy (and thus 16n) troubleshooting tip: Try a different USB cable.

Julian_Edwardes · 2019-10-03T17:48:40.428Z

Something like that it seems, confusing as a laptop or the test browser read 16n fine… my 16n now has a Dr Dre Beats cable and adapter