1. Introduction

Older style thermostats and some tilt-triggered alarm systems both historically used exactly this kind of switch, a sealed capsule containing a small blob of liquid mercury that rolls to complete or break a circuit depending on orientation. In this experiment, a mercury tilt switch module is wired to the STM32F070RB as a simple digital input, and the microcontroller reports the detected tilt state over UART.

2. Scope

This experiment covers understanding how a sealed mercury capsule acts as a tilt-actuated electrical switch, and reading its digital output with an internal pull-up. This reinforces the simple digital GPIO read pattern used across this series, applied here to a tilt-actuated sensor.

3. Prerequisite

3.1 Hardware

• STM32 Nucleo-F070RB development board

• Mercury tilt switch module

• Breadboard and jumper wires

• Micro-USB cable

• PC with PuTTY

3.2 Software

• STM32CubeMX (standalone)

• STM32CubeIDE

• ST-LINK USB driver

• PuTTY, or an equivalent serial terminal application