The Complete Guide to STM32 Microcontroller Sensor Applications: Detailed Explanations of Sensor Types, Configurations, and Applications, Sensing the World

# 1. Introduction to STM32 Microcontroller Sensors

Sensors are devices that convert physical or chemical quantities into electrical signals and play a crucial role in modern electronic systems. The STM32 microcontroller integrates a variety of sensor interfaces, providing robust hardware support for sensor applications.

This chapter will provide a comprehensive introduction to STM32 microcontroller sensors, including the classification, principles, interfaces, and communication protocols of sensors. By deeply understanding the working principles and characteristics of sensors, developers can fully utilize the sensor functions of the STM32 microcontroller to realize various innovative applications.

# 2. Types and Configurations of Sensors

### 2.1 Classification and Principles of Sensors

Sensors can be classified according to their detection principles and the physical quantities they respond to. They are mainly divided into the following three categories:

#### 2.1.1 Physical Sensors

Physical sensors detect physical quantities such as temperature, pressure, flow rate, acceleration, and position. Their working principles are based on physical laws and material properties. Examples include:

- **Temperature Sensors:** Utilize the change in resistance or voltage of thermistors or thermocouples with temperature to measure temperature.
- **Pressure Sensors:** Utilize the change in resistance or charge of strain gauges or piezoelectric materials with pressure to measure pressure.
- **Flow Sensors:** Utilize principles such as thermal, turbine, or ultrasonic to measure the flow rate of fluids.

#### 2.1.2 Chemical Sensors

Chemical sensors detect the presence or concentration of chemical substances. Their working principles are based on chemical reactions or adsorption/desorption processes. Examples include:

- **Gas Sensors:** Utilize the change in conductivity produced by semiconductor or metal oxides reacting with specific gases to detect gases.
- **Biosensors:** Utilize the electrical or optical signals produced by the combination of enzymes or antibodies with specific biomolecules to detect biomolecules.

#### 2.1.3 Biosensors

Biosensors detect biological signals such as electrocardiograms, electroencephalograms, and electromyograms. Their working principles are based on the generation and transmission of bioelectrical signals. Examples include:

- **Electrocardiogram Sensors:** Measure the electrical signals produced by the heart using electrode patches to obtain an electrocardiogram.
- **Electroencephalogram Sensors:** Measure the electrical signals produced by the brain using electrode caps or grids to obtain an electroencephalogram.

### 2.2 Interfaces and Communication Protocols of Sensors

The connection methods and communication protocols between sensors and microcontrollers or other devices determine the efficiency and reliability of data transmission. There are mainly three types of interfaces:

#### 2.2.1 Analog Sensors

Analog sensors output continuous analog signals, the amplitude or frequency of which is proportional to the measured physical quantity. Examples include:

- **Thermistors:** Resistance varies with temperature.
- **Piezoelectric Sensors:** Charge varies with pressure.

#### 2.2.2 Digital Sensors

Digital sensors output digital signals, the value of which is proportional to the measured physical quantity. Examples include:

- **Digital Temperature Sensors:** Output digital temperature values via I2C or SPI interfaces.
- **Digital Pressure Sensors:** Output digital pressure values via UART or USB interfaces.

#### 2.2.3 Wireless Sensors

Wireless sensors transmit data to receiving devices through wireless communication technologies such as Bluetooth, Wi-Fi, or Zigbee. Examples include:

- **Bluetooth Temperature Sensors:** Transmit temperature data via the Bluetooth protocol.
- **Wi-Fi Gas Sensors:** Transmit gas concentration data through the Wi-Fi network.