This page describes how to connect a moisture sensor with analog data output. If you need a digital output you can modify the setup easily.

A sketch how to connect moisture sensor with the raspberry:

See also e.g. RasberryPi 3 pin layout for information about the pin numbers.

Client configuration:

More about client configuration.

About hardware

The moisture sensor consists of two parts, YL-69 (probe) and YL-39 (logic).

YL-39 has two pins on one side that is connected to YL-69 and four pins on the other side:

• VCC: 3.3V (connected to Raspi 3.3 VDC Power)
• GND (connected to Raspi Ground)
• A0 : analog output (connected to CH0 on MCP3008)
• D0 : digital output that goes LOW or HIGH only (can be optionally connected to MCP3008).

The MCP3008 chip is connected to Raspi using the following scheme:

• VDD: 3.3V
• VREF: 3.3V
• AGND: Ground
• CLK: Pin #23 (SCLK)
• DOUT: Pin #21 (MISO)
• DIN: Pin #19 (MOSI)
• CS/SHDN: Pin #24 (CE0)
• DGND: Ground

Once wired, see pi4j module for the software implementation.