Adafruit KB2040

Overview

The Adafruit KB2040 — Kee Boar Driver — is a Pro Micro-footprint development board built around the RP2040 and designed specifically for custom mechanical keyboard builds. It combines the best features of three popular keyboard boards: the Qwiic / STEMMA QT connector from SparkFun's Pro Micro RP2040, the castellated USB D+/D- pads from the Elite-C, and Adafruit's own NeoPixel, 8 MB flash, and BOOT button additions.

The board provides 20 GPIO pins (18 on castellated pads plus 2 on the STEMMA QT connector) with four 12-bit ADC channels, two I2C controllers, two SPI controllers, and two hardware UARTs. A 3.3 V regulator rated at 500 mA peak powers the logic, while a jumper-selectable RAW 5 V output with either a 500 mA polyfuse or a 2 A direct connection allows keyboard matrix power.

For firmware, QMK is the most popular choice for traditional keyboard layouts, while KMK (CircuitPython-based) and CircuitPython's built-in keyboard HID library offer more accessible customisation. The RP2040's native USB means the board is a true HID device without any USB bridge chip. An RGB NeoPixel and a BOOT button serve double duty as a user LED and reset-to-bootloader mechanism.

The Pro Micro footprint ensures the KB2040 is a drop-in replacement in the many open-source keyboard PCB designs that target that pinout, greatly expanding its compatibility with community keyboard projects.