Bluetooth ZMK on Mac

Recently I’ve been fine-tuning my ZMK configuration. My split keyboard uses two nice!nano controllers, which are meant to connect flawlessly to my machine. However, I, and as ZMK’s GitHub issues would indicate, many other Mac users, have encountered that a full reboot is required to connect a macOS machine to the keyboard after flashing new firmware.

I have found that the following steps work reliably to reconnect the keyboard over Bluetooth after flashing new firmware, without requiring a reboot:

1. In the macOS “System Settings” under “Bluetooth”, select the ⓘ character next to your keyboard under “My Devices”, and click “Forget This Device…”
2. Flash both the keyboard halves with the setting_reset UF2
3. Finally, flash the both the keyboard halves (central first, then peripheral) with your new firmware.
4. From the “Bluetooth” settings menu, select the keyboard and press “Connect”.

For this reason, I generate a fresh reset UF2 along with every firmware change - I don’d believe it’s always necessary to rebuild this UF2, but it takes a matter of seconds.

This should cause the computer and keyboard halves to freshly pair. This has worked consistently for me, and I hope the same is true for you.