Description Chain DualKey is a programmable dual-key input development board built around the ESP32-S3FN8 controller. It combines two hot-swappable blue-switch mechanical keys, two programmable RGB LEDs and a compact enclosure for macro keyboard, HID input and smart control applications. Chain DualKey includes a built-in 350mAh lithium battery and low-power operating modes, so it can work as a small wireless or USB-connected input controller. The pre-installed Chain macro keyboard firmware supports USB and BLE connections and can emulate HID input devices. After Chain DualKey is powered on, users can connect to the device AP hotspot and configure HID function mapping through the built-in web page. The same mapping workflow can also control expansion nodes, making Chain DualKey useful for smart home shortcuts, keyboard peripherals and custom macro controls. Features ESP32-S3FN8 controller: Chain DualKey uses an ESP32-S3FN8 with an Xtensa LX7 dual-core processor and 8MB Flash. Dual mechanical input: two hot-swappable blue-switch keys provide tactile input for macro keyboard and control tasks. RGB feedback: two programmable WS2812B RGB LEDs help Chain DualKey show status, key feedback or custom lighting. USB and BLE HID: pre-installed firmware lets Chain DualKey emulate HID input devices over USB or BLE. Web configuration: HID mappings can be configured through the device web page after connecting to the AP hotspot. Battery powered: a built-in 350mAh lithium battery and low-power design support portable control workflows. Chain expansion: two HY2.0-4P expansion ports allow Chain DualKey to connect with other M5Stack Chain devices and sensors. Physical integration: rear LEGO-compatible holes and the lanyard design make Chain DualKey easy to mount or carry. Specifications SoC ESP32-S3FN8, Xtensa 32-bit LX7 dual-core processor, 240MHz clock frequency Flash 8MB Wi-Fi 2.4 GHz Wi-Fi Power Input USB: DC 5V Battery 350mAh lithium battery RGB LED 2 x WS2812B Operating Temperature 0-40 C Standby Current Power-off mode (VBAT): DC 4.2V @ 8.97uA; deep sleep mode (VBAT): DC 4.2V @ 107.64uA; USB 5V power without battery: DC 5V @ 41.7mA Product Size 47.9 x 34.3 x 23.9mm Product Weight 23.7g Package Size 63.0 x 72.0 x 28.0mm Gross Weight 39.3g Applications Smart home scene control using Chain DualKey as a compact shortcut controller. Macro keyboard workflows for common commands, media actions or productivity shortcuts. USB or BLE HID input projects based on ESP32-S3. Keyboard peripheral prototypes with hot-swappable mechanical keys and RGB feedback. Home Assistant input device integration for local automation control. Product List 1 x Chain DualKey 1 x Keycap Sticker Other Content Configuration Workflow Chain DualKey ships with Chain macro keyboard firmware. After startup, connect to the device AP hotspot and use the built-in web page to set HID mappings for the local device or connected expansion nodes. Charging, Restart And Download Mode Charging: power Chain DualKey through USB DC 5V to charge the built-in lithium battery. Restart: use the documented restart workflow when firmware or input mapping changes require a reboot. Download mode: follow the product document to enter firmware download mode for development and firmware updates. PinMap Highlights KEY KEY_1 uses G0 input; KEY_2 uses G17 input. RGB LED WS2812 data uses G21 input; WS2812 power enable uses G40. ADC SWITCH_1 uses G8, SWITCH_2 uses G7, ADC_BAT uses G10, ADC_VBUS uses G2, and ADC_CHARGE uses G9. USB USB_DN uses G19 and USB_DP uses G20. HY2.0-4P 1 GND, 5V, UART1_RX on G48 and UART1_TX on G47. HY2.0-4P 2 GND, 5V, UART2_RX on G5 and UART2_TX on G6. When configuring the ADC switch pins, do not set SWITCH_1 or SWITCH_2 as high-level outputs, or Chain DualKey may not power off normally. Resources Chain DualKey product document Chain DualKey UiFlow2 quick start guide Chain DualKey Arduino quick start guide Chain DualKey factory firmware usage tutorial Chain DualKey schematic PDF Chain DualKey model size PDF ESP32-S3 datasheet for Chain DualKey controller M5Stack Chain series driver library Chain DualKey Home Assistant integration guide Chain DualKey factory firmware source code Chain DualKey documentation PDF FAQ What is Chain DualKey used for? Chain DualKey is used for macro keyboard input, smart home control, HID shortcut control and ESP32-S3 input development. Does Chain DualKey support wireless use? Yes. Chain DualKey has a built-in 350mAh lithium battery and supports BLE HID workflows through the pre-installed firmware. Can the keys be replaced? Yes. Chain DualKey uses two hot-swappable blue-switch mechanical keyboard keys. How are HID functions configured? After Chain DualKey starts, connect to its AP hotspot and configure HID mapping through the built-in web page. Which expansion ports are available? Chain DualKey provides two HY2.0-4P expansion ports for M5Stack Chain series lateral expansion.
