Automatic sprinkler system with Micro:bit

Purpose of this project:

This project consists of creating an automatic watering system for plants, which triggers a water supply only in case of need. Suitable for a single plant or a small plantation, this system can be replicated at different scales. It will allow you to maintain your plants in your absence, or to manage the growth of species particularly sensitive to moisture by setting fine adjustments. This automatic watering device will provide an opportunity to study the use of an analog signal from a sensor to activate a fairly powerful actuator (here an electric pump) using a relay.

Operating principle

Located close to the plant or plants to be monitored, the installation monitors the state of drought of the earth using a dedicated sensor, characterizing the resistance of the earth between two electrodes. This information is then used to activate, if necessary, a 5V pump, driven by a Micro:bit board to supply plants with water.

Required components

• a Micro:bit board a GPIO board
• a soil moisture sensor
• a 5V water pump a relay
• A water tank
• connecting wires
• test plate

Mounting the automatic watering system

To make the mounting, you can connect

For the soil moisture sensor:

• pin (+) to pin 3.3V from Micro:bit
• pin (-) to pin GND from Micro:bit
• pin (S) to pin P1 from Micro:bit

 For Relay :

• pin (+) to pin 3.3V from Micro:bit
• pin (-) to pin GND from Micro:bit
• pin (S) to pin P2 from Micro:bit
• pin ON to pin (+) from 4 batteries

For the water pump:

• the first terminal at the COM pin of the relay
• the second terminal at the GND of the Micro:bit

Mounting 1

Mounting 2

Makecode program

Here is the Makecode program for the automatic watering system: