Building a Wireless Corne Keyboard

In my earlier post on building a Corne keyboard, my first Corne keyboard stopped working after using it for a month. I tried different ways to fix the keyboard. None of them helped.

Since the keyboard is already kind of broken, I thought why not experiment with it a bit further? Just to see how far I can go. What if I could even upgrade the keyboard, from a wired version to a wireless one?

With wireless split keyboards, there are a few extra benefits:

• No TRRS cable is needed to connect between each side of the keyboard.
• No USB cable is needed to plug into the computer (except for charging). The keyboard works via Bluetooth.
• Which means each side of the keyboard is completely free from each other, and even from each other. I could put each side of the keyboard anyway or anyhow I want - as long as both sides are in the Bluetooth range.

I did some research. I found that it is possible to make a wireless version of the Corne keyboard using the existing parts I have. I would take the chance to fix my previous mistakes too.

Getting Parts

• 2x Nice!nano v2 controllers from BeeKeep (~2,200THB / $63. Yes, this thing is not cheap.)
• 5x female, 5x male round straight Pin Headers from Shopee (175THB / $4.9)
• 2x Lithium-Polymer 3.7v 160mAh (361230) from Lazada (100THB / $2.80)

Socketing and installing Nice!nano controllers

I remove the controller, the OLED screen, and the TRRS jack from the PCB. I left the reset switch on the board.

I socket the board using the male and female 2.54mm pin socket headers. The female goes to the board.

The male pin headers go to the Nicenanos controllers. I put the masking tape between the pin headers and the socket. It's the technique I learned from many YouTube videos.

Then I solder the nicenano controller to the pins. From now on I can remove the controller from the board without having to desolder it. I can take the controller to use with another board too.

Installing batteries

The Corne PCB I'm using doesn't have a battery socket. I install the battery on the Nicenano controller instead.

The battery I'm using is the Li-po 3.7v 160mAh (361230). It sits perfectly underneath the Nice!nano controller.

Nice!nano & ZMK Firmware

Going from a wired to a wireless build requires me to change the controllers from the Sea Micro to the Nice!nano. And with this, I have to switch the firmware from QMK to ZMK too, which is new to me.

Luckily, ZMK has very good documentation. I follow the Installing ZMK guide and can flash the first firmware within minutes.

Customizing the firmware confused me at first because I had to work with the plain text .keymap file which took me a good amount of time to understand how it works. Once I get it and can see the pattern, then it's not too confusing anymore.

Later on, I discovered the Keymap Editor app for ZMK that provides a very nice UI to customize the keymap. It supports a lot of ZMK features. It can connect to my ZMK config repo on GitHub, and can commit my changes back to GitHub, the new firmware gets built via GitHub Actions. I can then download and flash the firmware to the Nice!nano.

My keymap and config are at the repo @armno/zmk-corne on GitHub.

Flashing the firmware

Flashing the firmware has more steps compared to using VIA for QMK.

Once a version of the firmware is built on GitHub Actions, I can download the firmware files, which include 2 firmware files in each build - one for the left side and another one for the right side of the keyboard. Flashing the firmware is done one side at a time. I usually flash the left side first.

1. Put the left side into the Bootloader mode by pressing the reset switch twice, or short-circuiting the GND and RST pins twice. I usually use a tweezer to double-tap both pins. When the Nice!nano is in the Bootloader mode, there is a blue light blinking.
2. Plug it into a computer with a USB cable. It will recognize the controller as a storage drive named NICENANO.
3. Copy the firmware of the left side corne_left-nice_nano_v2-zmk.uf2 to the NICENANO storage. When it is done, the storage will be unmounted automatically.
4. Repeat for another side of the keyboard.

Result

Here is my wireless Corne keyboard:

With all the cables removed, it looks much cleaner. It is also more portable because I don't have to take 2 cables every time with the keyboard anymore.

The battery life is questionable. From what I learned from YouTube videos, typically the battery should last about a week on the left side, and 2-3 weeks on the right side.

But my keyboard's battery life is much shorter. It only lasts a few days hours 🤯 before empty. I don't find a reason why it is like that yet. To me, charging every day is not a problem because charging time is very fast. It takes less than an hour to charge for a full day of use.

Overall, I'm very happy with the result and I wish I could have done this earlier. Building was fun. I learned a few new things.

Happy building. ✌️