Home | ER-101 | ER-102 | ER-301 | Wiki | Contact

I2C communication with Monome Teletype


sure i uploaded many time the firmware already, without any problem… i download the teletype firmware from this tread, this one : https://forum.orthogonaldevices.com/uploads/default/original/2X/b/bd88d047040a367185b4fec8adc5095b4eb658fc.zip

but you call that a source code, maybe it’s my problem ?


That is exactly the problem. :wink:


ok, so i guess i have to learn how to create a firmware from a source code now :slight_smile:
thank you !


No no. This is the one that you want:

er-301-v0.3.06-unstable-48kHz.zip (1.4 MB)

Apologies for hiding it in this thread. I’m going to add it to the v0.3.xx thread now like I should have before.


oh great ! thank you ! but i’m still interrest to learn how people doing it :slight_smile:


ok, i did the mod, but i unsolde (not my choice !) the diode… my skills are not relly great but it the same as to short out ?


I admire your fearless nature, I was too nervous to do this myself though I really wanted to give it a try. Instead I sent it off to more capable hands. The one thing all of this has motivated me to do is to signup for a soldering class.


Oops. No it is not. You have two options:

Option 1:

  • Solder the diode back on (in the same orientation).
  • Start over again.

Option 2:

  • Leave the diode off.
  • Solder a small piece of wire/metal across the empty pads where the diode used to be.


Option 2 is what i did ! And all work great now :wink:


@odevices any comment on SC.CV being delayed compared to SC.TR? is this something that could be changed in a future version? completely understandable if it’s not possible or has lower priority, and much appreciated that you were able to dedicate the time to make this integration possible at all.


I tried to set this up today, but can’t get a signal over from the teletype to the er-301.

I did the diode-bypass mod (not quite sure how that could go wrong, the wire is in place and has good solder joints). I added the cables according to the pictures (with the GND wire from ER-301 crossing over the other two on TT). I’m using a bus board i made from the monome-kit and i’m also using that busboard with multiple tt-expanders and just friends without issues (so I don’t think the problem is the busboard). I’ve updated both firmwares (teletype: 2.1.0: 205521A-ER301, ER-301: 3.0.7) and I set the ER-301 up so that the teletype-connection is enabled. I can add the teletype-units to a channel on the ER-301 and I can type the sc-commands into teletype, but nothing happens on the output of the sc.cv unit on the ER-301.

Is there anything I missed or anything I could try to test in order to figure out where the problem is?


Did you think to enable teletype in the Er301 setting ? I forgot it and lose a bit of time because of it today…


Does anyone know where I could reliably get the soldering mod done in the UK? Poor eyesight and coordination caused by neurological issues pushes this beyond my capability. Anyone got any ideas? Not sure I want to send my beloved ER-301 to “some dude on the internet” so I would prefer a legit service provider of some sort if poss.


I might try @kel or @Joe - I know one of those guys have offered their services for this type of work.


Idea 1
While trying to reproduce your problem, I noticed the following (confusing) behavior:

  • Teletype integration needs to be disabled and re-enabled in order for a newly selected slave address to take effect.

So if you recently changed the slave address (which should be 0xB0), it might still be using the old address until you reboot or disable+re-enable. I’ll fix this in the next release so that changing the slave address takes immediate effect.

Idea 2
Another possibility is that the port number on the unit and the port number you have specified in the SC.CV command are not matching?

Idea 3
I would double-check that the SCL and SDA wires are not swapped. I’ve done it a number of times myself.

Idea 4
Perhaps the change in voltage is too small to see in the ER-301 scope? Test with larger values. SC.CV 1 V 5


I have confirmed that it is because I (myopically) enforce a minimum CV slew time of about 2ms. I will remove this minimum in the next release.


I took some time today to get the Teletype and ER-301 connected.
Did the mod: not the most beautiful job, but seems to have done the trick:

Updated the Teletype firmware, updated the ER firmware, and they are now happily conversing! Everything works as advertised, and have not noticed any issues whatsoever (so far).

Just wanted to say thanks to all parties involved in making this happen!
Your time, skills, and generosity is deeply appreciated.
Very sincerely,


The TELEX defaults to 1ms (which is what I believe the TT defaults to as well). Both allow SLEW to be set to 0.

Hope this is helpful. :slight_smile:

Thanks for all the wonderful work on the ER side of the integration! It was super-easy to integrate with!


@laborcamp I like the cable. Did you make it yourself?

@bpcmusic It all has to do with some code gymnastics that I needed to do to remove the timing jitter between i2c and the ~2ms frame sync of the audio processing. That is all fixed now and purring away on the test bench. If I see no hiccups for the next day or so, I will release the new version which enables zero slew.


No! @bpcmusic included this beauty with the powered “backpack” for Teletype I got from him!!!