Controller chip
The microcontroller — the keyboard's brain.
The controller (microcontroller, or MCU) is the chip that reads keypresses and sends them to your computer. The big constraint is wireless: only the Nordic nRF52840 has the radio for low-power Bluetooth and pairs with ZMK. For wired boards the modern default is the cheap, powerful RP2040; the older ATmega32U4 still runs much of the QMK world; STM32 powers many higher-end boards.
The Raspberry Pi chip: cheap, fast, plentiful and well supported by QMK/Vial and KMK. The sensible modern default for a wired board. Found on boards like the RP2040-based Elite-Pi and many newer kits.
The long-time QMK workhorse (Pro Micro, Elite-C). Mature and universally documented, though older and more memory-limited than the RP2040.
The wireless chip. Built-in Bluetooth Low Energy and excellent power efficiency, paired with ZMK firmware. Choose this if you picked any wireless option (nice!nano is the popular board).
A powerful 32-bit family used on many premium and group-buy boards, well supported by QMK. More headroom for RGB and features.
Every choice you'll see for this decision in the builder.
The Raspberry Pi microcontroller. Plenty of power and memory, cheap, and supported by QMK/Vial and KMK. Great default for wired boards.
- Cheap and powerful
- Excellent firmware support
- Easy to flash (drag-and-drop)
- No built-in wireless
Powers the classic Pro Micro and Elite-C. Endlessly documented and compatible, if a little dated and memory-limited.
- Universally supported
- Tons of guides
- Proven & reliable
- Limited memory
- Older, slower
- No wireless
The wireless brain (e.g. nice!nano), with Bluetooth LE and superb power efficiency. Pairs with ZMK. Pick this for any wireless build.
- Built-in Bluetooth LE
- Excellent battery life
- Pairs with ZMK
- Pricier
- ZMK has a learning curve
A powerful 32-bit family with headroom for heavy RGB and features. Found on many higher-end and group-buy boards.
- Lots of performance & memory
- Great QMK support
- Common on premium boards
- Pricier than RP2040
- No wireless
- Flashing slightly fiddlier