#1319

Not much to be sorry about. I made a mess while I was going so quickly on the build. Neglected other basic household duties. Basically, I was a slob and now I’m paying the price because my workspace is a disaster area. :wink:

#1320

I know the feeling!

“Disaster area” range from (Super OCD) “my pen is at a wrong angle” to (Super chilled) “house burned down, typing this from what’s left of my lawn” :slight_smile:

Anyways, super stoked at the prospect of (eventually) grabbing some expanders!

1 Like
#1322

Ok, got a second txo that I need to connect (total of tt + er301 + 2x txo)

  1. How do I place the jumper on my second txo to address it seperately from the first one? A link to where the addressing scheme on the txo is explained would be highly appreciated!
  2. What happens if I have two txo’s on the same address? Is it safe or will I burn something?
  3. Is it still recommended to daisy chain i2c? I’m asking because my (black PCB) teletype seems to have 4x i2c connectors, and currently I’m doing a star configuration tt->301 and tt->txo, but with recent issues that might be related to i2c, I wanna set this up as correctly as possible.
  4. If daisy chaining is recommented,I guess it’s to distribute the powering of the bus to multiple mudules or? But isn’t the 2x i2c on the txo and the 4x i2c on the tt not simply electrically shorted? Please enlighten me!
#1323

You can find the TXo documentation up on GitHub:

image
Actually - more likely your TT will just freeze at some point. Though, that doesn’t rule out accidental destruction of the local solar system. :wink:

I always do. Keep those runs short. :slight_smile:

Yes. The i2c lines are just shorted. But, the wiring reduces the quality of the bus (with a certain pull-up amount). Sorter wires = more stable bus.

1 Like
#1324

Thanks! Really appreciate it! Will dig right away!

There’s just thing I don’t get:

Wouldn’t that imply a star configuration is better? Like how they normally recommend wiring power in larger eurorack systems…

I’m not questioning you, just trying the wrap my head a bit around it…

#1325

Disclosure: I’m no Expert in this Stuff :slight_smile:

As things are all “shorted together” on the i2c bus, it really is about the overall length of wire on the bus. I have found, where there is a lot of long cables, the bus can become less stable. Keeping the electrical impact of the cabling to a minimum is the priority over any topology. In my rack, as modules are side by side, there is less wire on the bus when I jumper between them as opposed to running longer and longer wires from my busboard to each adjacent module.

Make sense?

2 Likes
#1326

Is this common among your experience with two modules sharing the same address? I would have thought they’d just output the same thing.

#1327

Makes total sense. Would you say it would be worth the effort to get cables shorter than the “standard” ~15cm, like say 5-7cm?

#1328

probably doesn’t matter for your config. matters more when there is lotsa i2c devices.

#1329

Generally the bus leader will require the follower it addressed to send an ACK bit before the leader will continue sending data; this is enforced in hardware. So if you have two devices with the same address, both will try to ACK “simultaneously”. So I would guess it might work, or might crash, or drop packets, or any number of other things falling under the umbrella of “undefined behavior” – I don’t think the I2C spec defines how to arbitrate this, since you’re not generally supposed to wire it this way, but I could be wrong. It might work fine for certain hardware combinations but I would probably not want to rely on it.

4 Likes
#1330

@bpcmusic per the ludicrously small hint, I desoldered the female pin connectors on my TXi and resoldered the two board directly for more mechanical stability; it indeed survived :+1:

IMG_20190714_194633272
IMG_20190714_194633272.jpg3024×4032 2.97 MB

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#1331

that made me ludicrously happy. now, about that teensy… :wink:

1 Like
#1332

IMG_20190717_144449324
IMG_20190717_144449324.jpg3120×4160 3.32 MB

Just received two 2nd hand txo in the mail. One of them seems to have a broken off leg. Suppose that should be fixed, right. Plan is to reuse a resistor/diode leg, sounds sane?

I’ve been looking at these tiny legs on my other units wondering if they provide enough contact in the female header, although they seem to be fine…

#1333

Yes, but fair warning that you are likely to break the other contact when you cut away the plastic around the pins. I soldered one pin at each corner of all my Telexes to prevent them from coming apart while not making future disassembly impossible.

#1334

Ah, my plan was just to solder a resistor leg on instead of the broken off pin, and keep everything else…

#1335

the pairs of “two pins” are just for additional stability and additional ground plane tie-ins. each pin provides the same connectivity - which is also redundantly connected on the big headers.

it should work just fine with the broken pin (without the slight stability benefits). i’d just zip tie those boards together and call it a day. :slight_smile:

like this:

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#1336

Thanks @bpcmusic! The resistor leg was fine, but modules still have a tendency to come loose, mostly between the main board and the panel board.

I just tried zip ties, but it adds a bit to the width of the module, resulting in small gaps between modules, good for ventilation, bad for everything else…

Are both sets of double-pins in either end of the board for stabilization only? If so, I might go with @jnoble suggestion, but using one of the double-pins on either end…

#1337

Yes, a resistor leg would work fine also. I didn’t have good results with zip ties, even using the thinnest 3" ones I have around.

I haven’t had any issues with Teensies (Teensys?) coming loose so they sit happily in the sockets.

Aside, and unrelated … has anyone thought of implementing log/expo envelope curves on the TXo? That’s probably the only thing on my wish list, these modules are nearly perfect for me as is. :slight_smile:

#1338

I seem to have a problem with one of my new 2nd hand txos, it’s very unstable.

  1. LED go off at random
  2. It doesn’t react to a jumper in the first row (so jumper in first row => address 1-4, not 5-8, jumper tin first two rows => address 9-12 not 13-16)
  3. With it in the mix, the teletype sometimes freezes.

Without the problematic txo, teletype + 3 txo seems to be running just fine (running a txo workout test since 30 mins or so), haven’t tried with the er-301 yet. Feels very much like a loose connection, any idea how to debug the build? I’m not sure, but I think it’s build by @bpcmusic…

#1339

try this on the output with the envelope.

TO.CV.LOG x y
translates the output for CV output x to logarithmic mode y; 
y defaults to 0 (off); mode 1 is for 0-16384 (0V-10V), 
mode 2 is for 0-8192 (0V-5V), mode 3 is for 0-4096 (0V-2.5V)

Here is a pic of the envelopes in action:

Schematics and stuff are up on the GitHub. Not even sure where to advise that you start - random LEDs don’t make any sense given how the thing works. I would certainly make sure that both of the halves are firmly connected and not loose in any way.

It sounds really sick. Regardless of whether I built it or not, I’d be happy to take a look at it. PM if you wanna set that up.

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