In the below image, you can find the actual hardware setup to build an automatic plant watering system using a soil moisture sensor.

In the below image, you can find the actual hardware setup to build an automatic plant watering system using a soil moisture sensor. In this setup, you can find that I am powering the Arduino UNO R4 Wi-Fi through a Type C USB port. So I don’t need to provide an external power supply; I am able to provide a power supply to the water pump from the Arduino 5V pin itself.

While we power Arduino through a USB port, it bypasses the voltage regulator present on the Arduino Uno R4 Wi-Fi board, so we can consume current up to 2 mA from the 5V pin, which is enough for driving all these things. In the below image, you can see that I am using a 5V water pump motor and a single-channel 5V relay module, which has 3 pins on the input side and 3 pins on the output side. On the input side, it has three pins, namely VCC, GND, and Signal (IN) pin. We can control the relay output using a signal pin by providing either 0V or 5V.