OMX-27 - a DIY Mechanical-Key Keyboard/Sequencer

Re: flashing the firmware.
How do you go about doing this? The build guide suggests that it’s a simple matter, but using the Arduino app on my Mac, I’m having no luck. I can’t seem to open any of the hex files in the app for flashing.
Any help would be appreciated!

Is the arduino ap recognizing that you are connected? Could be the usb cable?

Yes, the teensy is recognized, but I just don’t know how to open up the hex file and program it in the app. With the older Teensy app it was simple, but sadly that program says that all of the OMX hex files are “unreadable”. And with the Arduino app, I’m not sure how to open the hex files at all~~

How are you downloading the hex files? If I click on the hex file on the releases page here it downloads for me and Teensy Loader is fine with it:
Screen Shot 2021-04-30 at 9.18.10 AM

However if I ever get presented with a ‘text file’ view in the browser, I have trouble getting the hex files to be read correctly, even after saving it and/or renaming the file extension. Sometimes “right click and save as” on the file works, but if that fails I just download the whole git project as a zip and then the .hex file is always intact.

(Edit to add: I just dragged the .hex file onto the Teensy loader window, no Arduino app needed which handles .ino etc files, not the compiled .hex files. In case that helps clarify for anyone?)

Hope that helps.

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Oh, this is now in my kit queue, absolutely.

@okyeron, have you done any research into optical or hall effect switches? Its a ways out before either option can start going into kits, but I’m seeing some promising work done by Wooting and Gateron Lekker switches that might be feasible to bring into PCB kits built specifically for them in the future and would allow for velocity sensitivity at the very least if not something approaching MPE.

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You need the Teensyduino version of Arduino. (or more specifically the Teensy Loader portion)

This guide I wrote is somewhat out of date, but covers the general approach:

Let me know if that helps.

Best I can tell the Lekker switches are not yet available for individual purchase, but only as part of built keebs.

It’s orbiting on my radar, but will depend on when the switches are generally available for sale.

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Thanks for getting back to me!

I DLed the Teensyduino program again but still no luck with flashing the hexes.
The cable and teensy are working fine (I can flash 16n firmware with no issue) but none of the OMX firmware can be opened in the Teensy Loader program. Each one reads as “unreadable” and the “program” button is greyed out.
Do I need to open the hex in the Teensyduino program or simply have it open? I can’t open any of the hexes in Teensyduino (I guess it doesn’t deal directly with hexes??) How do I get the firmware files uploaded into Teensyduino?
Screen Shot 2021-05-01 at 9.31.09

Should work if you just drag and drop the hex on to the Teensy Loader.

Try also hitting the reset button on the teensy

Check to see that the correct board is selected on Teensysuino?

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Also, @endurance - make sure that you download the whole Git repo, not just the firmware file - there’s still sometimes a problem with corruption in individual file downloads.

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Thanks for all of the help and advice! With some above-and-beyond assistance from @okyeron everything is working a-ok. I’m not sure exactly what the issue was, but after downloading the entire Github repo and using freshly DLed version of Teensy Loader, the firmware flashed just fine.
Thanks again everyone!


Hi is this the forum to ask about any questions or bugs found on OMX-27?

Yes you can ask questions here, but the discord is easier for support issues. I will DM you a link.

The OM Mode channel setting you mentioned is currently broken so yes - this is a bug.

Cool thx a link will be good. This sequencer is awesome! :slight_smile:

Got my kit on friday, and built everything during a couple of hours on saturday. Really a nice, well planned kit, and a very nice product in the end :slight_smile:


So I’m like 99.99% sure this will work, but before I do something that requires any desoldering, @okyeron, are you able to confirm if this is a drop in replacement for the OLED? I’m all about those yellow displays!!

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If the picture is accurate (for the pin order), then yes. :slight_smile:

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What are the physical dimensions of this?

12.32 in x 2.55 in (or 312.92 mm x 64.81 mm )

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Cool. Just picked one up from your shop.

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1.3.0 firmware update now available

Release OMX-27 1.3.0 · okyeron/OMX-27 · GitHub

There’s also a cheat-sheet in progress to help navigate modes, etc.

OMX-27/OMX27_CheatSheet.pdf at main · okyeron/OMX-27 · GitHub