Moisture Sensor User Manual Waveshare Moisture Sensor User Manual 1. Features Operating voltage 2.0V-5.0V Output type Analog output Detectable depth 38mm Dimensions 20.0mm*51.0mm Fixing hole size 2.0mm Operating principle: This module is an application of the current amplification by a transistor. When the water in the soil is sufficient enough to conduct the current between the base and the positive power supply, a certain amount of current is generated between the base and the emitter. And in a mean while, an electric current is produced in a certain amplification factor between the collector and the emitter, and applied to the resistant in the emitter to produce a voltage. Then, this voltage will be collected by an AD converter. 2. Applications This module can be applied to automatic watering system, soil moisture detection, Automatic irrigation system, etc. 3. Interfaces Pin No. Symbol Descriptions 1 AOUT Analog output 2 GND Power ground Positive power 3 VCC supply (2.0V-5.0V) 4. How to use We will illustrate the usage of the module with an example of soil moisture detection by connecting a development board. Download the relative codes to the development board. Connect the development board to a PC via a serial wire and the module to the development board. Then, power up the development board and start the serial debugging software. Here is the configuration of the connection between the module and the development board. Port STM32 MUC pin AOUT GPIOA.6 1 Moisture Sensor User Manual Waveshare GND GND VCC 3.3V Port Arduino pin AOUT A0 GND GND VCC 5V Here is the configuration of the serial port. Baud rate 115200 Data bits 8 Stop bit 1 Parity bit None Insert the sensor into the soil. Water the soil little by little, and you may find the serial output changes from Im thirsty to I had enough 2