Polyphonic Earthsea

@scanner_darkly over on Monome’s LINES forum just released a Polyphonic Earthsea firmware update that works on Ansible, White Whale, Meadowphysics, or Earthsea.

If you are working with the ER-301 Teletype mod and have a GRID and one of the devices listed above you can update the firmware (at the risk of losing your presets). This does NOT run on the Teletype, but it does work on the i2c bus allowing you to use the GRID to play your ER-301 with up to 8 CV’s/Gates, Just Friends, TXo’s, and the device the Polyearthsea is installed on.

This is his first release of the firmware and he’s looking for feedback and testing as it evolves:


Man, i was really looking forward to this while following the progress on instagram as i’m using my grid via ansible exclusively with the 301 and just friends. I did not know that there needs to be something inbetween the e.g ansible > er301 for powering the i2c master connection without using teletype, apparently a extra module, or some power board? Someone knows more?

Think of it like buffered vs. unbuffered CV.

The trilogy modules were never meant to be I2C leaders, so their their data pins are simply connected to the microcontroller. These tiny microcontroller I/O pins can’t sink or source very much current. To drive a clean I2C signal it is therefore necessary to “power” the bus using pull-up resistors.

There’s no need for a separate module but this enhancement would require some behind-the-panel upgrades. Brandon Cassidy’s (aka BPC Music) open source iiBackpack is made for enhancing Teletype’s I2C lines but would work fine for this purpose too. It is basically just a linear regulator and two resistors.

It would be “not difficult” to modify your module using dead bug soldering techniques.


So… presumably a 3.3 v linear regulator, a couple resistors, a power header, and a couple of headers for the i2c lines on a breadboard would get me where I need to go to hookup my white whale to my 301? Anyone care to draw this out so I don’t get into trouble?

Also, once I get it hooked up, what would I have to do in the 301 for it to recieve data from i2c (will it show up in globals) ?


Which hardware revision of ER-301? The earlier hardware requires a modification.

Check my link above for the iiBackpack and click through to the OSHPark page. There are images of the board layers which can show the way you’d hook it all up. For resistor sizing you may want to search on the Lines forum. 10k, I think, but don’t quote me on that.

This is probably different in v0.4xx but in v0.3xx there were settings for I2C address and activation. Then you use SC.CV and SC.TR units to access the incoming data. I presume that polyphonic earthsea sends gate and CV info via the first 8 channels of both units.


That is correct. From @scanner_darkly last night:

  • SC.CV ports 1-8 - pitch CVs
  • SC.CV ports 17-24 - volume CVs
  • SC.TR ports 1-8 - gates
  • SC.TR ports 17-32 - pattern starts (whichever ones are assigned) edit: looks like i forgot to do this so for now it will send to SC.TR 1-8 as well. i’ll change this in the future.
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FWIW, the ER-301 mod is very easy to do, just involves soldering a shunt around a resistor - easy peasy!

i’ve added a couple of pages to the wiki:

i2c set up
er-301 set up

here is an example of polyearthsea used with 8 voices on er-301:

there was some strangeness during testing (as if SC.TR polarity would flip at some point), so keep an eye on it. i’ll do more extensive testing with er-301 when i get a chance.


this is so GREAT!!!
i’ll build my i2c powered board as soon as the infos will be posted, and will make the 301 i2c modification.

i hope you’ll be able to put it in the ansible retaining the original apps (especially kria) so i don’t have to destroy my budget and buy another monome module :smiley: :smiley: :smiley:

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yeah hoping i can make it work but remains to be seen. older trilogy modules come up fairly cheap so that might still be a viable option to consider (and with the trilogy modules you’ll be able to take advantage of the things ansible doesn’t have - knobs on earthsea will work as modulation sources, for instance).


I’m def going to flash my Earthsea module with this code once the “release candidate” is ready.

yes! absolutely no pressure :slight_smile: and, of course, thanks for your AWESOME work once more.

i often repeat to my students that we live in a sort of music technology renaissance, an incredible amount of extremely skilled and inspiring people doing their thing. <3

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i’ve posted new betas: Polyearthsea - Monome - lines

bugfixes, midi recording and learn, shnth support and other features.