Chain Key Mechanical Button STM32G031

Chain Key is an input module with a single mechanical button from the M5Stack Chain series. This compact module features a Blue-Switch type mechanical switch (tactile), which can be easily replaced when needed thanks to its hot-swap capability. This provides a clearly noticeable click feedback with every keystroke. Additionally, two programmable RGB LEDs are integrated to indicate status, effects, or feedback. The module is ideally suited for human-machine interactions or smart home controls where a robust physical button is required. Inside, a powerful STM32G031G8U6 microcontroller manages input and LED control. Communication with a host or other modules occurs via a UART-based cascade protocol, allowing multiple chain modules to be daisy-chained. Thanks to the two HY2.0-4P interfaces on the Chain Key, additional modules from the chain series can be seamlessly connected to create more complex and interactive applications. With its compact dimensions and modular approach, the Chain Key can be easily integrated into existing M5Stack ecosystems, enabling quick prototyping and flexible extensions. The durable mechanical switch and versatile connectivity make the Chain Key a reliable solution for a variety of projects.

Recommended Accessories:

• M5Stack Chain Dual Key with ESP32-S3 or other M5Stack Cores
• M5Stack Grove Cable

Features:

• Belongs to the M5Stack Chain series and can be seamlessly coupled with other chain modules.
• Features a single mechanical button as an input element.
• Equipped with a hot-swap capable Blue-Switch (mechanical switch) for tactile feedback.
• Contains two integrated RGB LEDs for programmable lighting or status indication.
• Integrated STM32G031G8U6 microcontroller as a powerful control unit.
• Communication via UART cascade protocol enables the daisy-chaining of multiple modules.
• Two HY2.0-4P expansion ports to connect additional devices from the Chain series.

Application Examples:

• Smart Home: As a programmable wireless switch for controlling lighting or other devices.
• Human-Machine Interaction: As a start/stop button or control element on machines or interactive installations.
• DIY Electronics Projects: Used as a customizable button in self-built control panels or robotics projects.
• Education and Prototyping: Ideal for experiments in workshops or testing IoT applications with physical input.
• Individual Control: As a single button for special applications such as a macro button on a PC or a dedicated trigger in photo booths.

Documentation: 

• M5stack Wiki
• Official M5Stack Forum

Technical Data:

• Manufacturer: M5Stack
• Manufacturer SKU: U206
• MCU: STM32G031G8U6 (32-bit microcontroller)
• Input Voltage: 5 V DC
• Communication Interface: UART (serial, cascade)
• Connections: 2× HY2.0-4P (for expansion/cascade)
• RGB LEDs: 2× WS2812B (programmable RGB LEDs)
• Current Consumption in Operation: approx. 28.2 mA
• Operating Temperature: 0 to 40 °C
• Dimensions: 23.9 × 23.9 × 34.4 mm
• Weight: 14.4g

Package Contents:

• 1× M5Stack Chain Key Mechanical Button STM32G031
• 1× Chain Bridge Adapter