Unit CardKB2

SKU:U215

Description

Unit CardKB2 is a card-sized 42-key portable keyboard input unit. Compact and lightweight, it is designed for everyday carry and embedded integration. Powered by the ESP32-C61HF4, it supports 2.4 GHz Wi-Fi 6. The preloaded firmware supports four communication modes — I2C, UART, BLE HID, and ESP-NOW — for flexible connectivity with host devices. An onboard HY2.0-4P connector enables communication in I2C/UART mode, while a USB Type-C port provides power supply and firmware flashing. Additional features include an RGB LED status indicator, a Reset button, a Boot button, and built-in input overvoltage protection, making it well-suited for wireless input, interactive control, and a wide range of portable applications.

Features

Equipped with ESP32-C61HF4, supporting Wi-Fi 6 / BLE wireless communication
Full keyboard input with support for multiple key combinations (single press, Sym, Fn)
Onboard RGB LED (XL-1615RGBC-RF) for keyboard status indication
Reserved M2 mounting holes for easy application integration
Power Supply:
- USB Type-C
- DC 5V

Includes

1 x Unit CardKB2
1 x HY2.0-4P Grove Cable (20cm)

Applications

Text input for portable devices
Human-machine interaction in embedded systems
Wireless control terminal for IoT devices
Educational programming and maker projects

Specifications

Specification	Parameter
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 (powered via Grove interface)
Product Size	84.7 x 54.3 x 1.0mm
Product Weight	22.4g
Package Size	170.0 x 120.0 x 8.0mm
Gross Weight	28.9g

Learn

Key Description

Aa Key (Caps Toggle):
- Single tap: Enables one-shot caps lock — types one uppercase character, then reverts to lowercase automatically.
- Double tap: Enables caps lock — tap or double-tap again to disengage and return to lowercase.
- Hold: Maintains uppercase output while held; reverts to lowercase upon release.
- The green LED lights up when caps is active and turns off when disabled.
Sym Key (Symbol Key): Combines with other keys to output symbols. The blue LED lights up when Sym is pressed.
Fn Key (Function Key): Used for mode switching and combination functions. The red LED lights up when Fn is pressed.
- Fn + 1: Outputs Esc
- Fn + D: Cursor up (↑)
- Fn + X: Cursor down (↓)
- Fn + Z: Cursor left (←)
- Fn + C: Cursor right (→)
Mode Switching (Fn + Sym + Number Key): The selected mode is saved automatically and persists after power cycling.
- Fn + Sym + 1: Switch to I2C mode (factory default) — white LED blinks 1 time
- Fn + Sym + 2: Switch to UART mode — white LED blinks 2 times
- Fn + Sym + 3: Switch to ESP-NOW broadcast mode — white LED blinks 3 times
- Fn + Sym + 4: Switch to BLE HID mode — white LED blinks 4 times

BLE HID Mode

Unit CardKB2 can function as a wireless keyboard and connect to any BLE HID-compatible device. Follow the steps below:

Press Fn + Sym + 4 to switch to BLE HID mode.
On your phone / tablet / computer, scan for nearby Bluetooth devices. The device will appear as CardKB2-xxxx (where xxxx represents the last four digits of the MAC address).
Pair and connect — the unit is now ready to use as a wireless keyboard.

For usage instructions for other modes (UART / I2C / ESP-NOW), please refer to the Unit CardKB2 User Manual & Registers.