The BDN9 is a fun little 3×3 macropad using the STM32F072 that lets you try out a few rotary encoders as well. What can you do with rotary encoders? That’s for you to figure out! Use it as up/down, page up/down, volume control, or whatever, get creative.
”With the ZMK Firmware that runs on Zephyr RTOS, people using our Pro Micro-based PCBs can install a supported Bluetooth controller into their keyboard to make it wireless.Danny NguyenOwner, Keebio