The M5Stack Unit CardKB2 is a compact, card-sized keyboard module designed for portable input and embedded applications. It features 42 keys in a lightweight form factor, making it suitable for on-the-go use or integration into custom hardware projects. The unit is powered by an ESP32-C61HF4 microcontroller with built-in 2.4GHz Wi-Fi 6, enabling both wired and wireless communication options. Pre-installed firmware supports four communication modes - I2C, UART, BLE HID, and ESP-NOW - allowing it to be used in a wide range of setups, from direct microcontroller input to wireless control interfaces. The board includes an HY2.0-4P expansion connector for easy integration with compatible systems, along with a USB-C port for power and firmware updates. Additional features include an RGB LED for status indication, dedicated Reset and Boot buttons, and built-in input overvoltage protection to help safeguard the device during use. Features * Powered by ESP32-C61HF4 with Wi-Fi 6 / BLE wireless communication support * Full keyboard input with support for multiple key combinations (single press, Sym, Fn) * Onboard RGB LED (XL-1615RGBC-RF) for keyboard status indication * Power Supply: * USB Type-C * DC 5V Specifications SoC ESP32-C61HF4 @ RISC-V 32-bit single-core, 120 MHz Flash 4MB Wi-Fi 2.4 GHz Wi-Fi 6 Keys 42-key keyboard, 1x Reset button, 1x Boot button USB Type-C Power supply / firmware flashing, default firmware log output: 115200bps @ 8N1 RGB LED 1x RGB LED Expansion Interface 1x HY2.0-4P Standby Power 5V@19.31mA (under Grove interface power supply conditions) Product Size 84.7 x 54.3 x 1.0mm Product Weight 22.4g Resources * Product Documentation Package Contents * 1x M5Stack CardKB2 Keyboard Unit (ESP32-C61) * 1x HY2.0-4P Grove Cable (20cm)