{ Tech Blog } - Raspberry Pi Tree Watering System

For a long time, I have been planning to create a Christmas tree watering system because I consistently forget to water the Christmas tree on schedule.

This year, I finally accomplished this task. The most challenging aspect was finding a reliable moisture sensor, as the one I initially purchased succumbed to rust within a few days. The rust caused the deep sticks of the sensor to break the connection, leading the sensor to incorrectly indicate dryness, and I ended up spending around a pound for nothing around the tree base.

In the next attempt, I used a regular copper wire as the deep stick for the moisture sensor. Although some rust covered the copper wires too, at least it continued to function.

Devices

Raspberry Pi (any model)
Relay JQC-3FF-S-Z
Moisture Sensor (Note: Avoid the linked sensor as it tends to rust and fail within a week. I recommend using regular copper wires instead.)
Water Pump

Siphoning Issue

Siphoning refers to the process of transferring a liquid from one container to another by using a tube or hose that runs from a higher level to a lower level.

When the water level in the source container is higher than the end of the tube, water will flow without the need for the pump to be switched on. Make sure that the end of the tube is positioned higher than the water level.

Storage: JsonBin

The system utilizes JsonBin to store logs. Visit the provided link, and obtain the box ID from the home page.

System Setup

Relay

Connect the relay to the Raspberry Pi:

VCC → Pin 2 (5V)
GND → Pin 20 (Ground)
IN → Pin 22 (GPIO 25)

Moisture Sensor

Connect the moisture sensor to Raspberry Pi:

VCC → Pin 4 (5V)
GND → Pin 6 (Ground)
DO → Pin 3 (GPIO 2) (Note: Replace the recommended sensor with two regular copper wires for better durability.)

Water Pump

Connect the water pump to the relay:

Plus → COM
Minus → DC Power Supply minus
Relay ON → DC Power Supply plus

Application Installation on Raspberry PI

$ git clone https://github.com/ypanshin/pi-tree-watering.git - clone the repository
$ cd pi-tree-watering - navigate to the project folder

$ nano package.json - update config section of package.json

"config": {
  "sensorPin": 3, // the pin that moisture sensor connected to.
  "relayGpio": 25, // the GPIO that the relay connected to
  "onInterval": 1000, // the interval in ms to check the moisture sensor when the relay is on (the pump is working).
  "offInterval": 60000, // the interval in ms to check the moisture sensor when the relay is off (the pump is not working).
  "pumpFlow": 1.5, // the pump flow in litters per minute
  "maxLogItems": 1000, // the maximum items in the log
  "binId": "box_6f937824ca2f42a8a471" // the box id
},

$ npm i && npm run build && npm start - install, build and run the application

Copy files to Raspberry Pi from another machine

scp -r ./dist pi@192.168.0.103:~/apps/pi-tree-watering/dist

Reset the logs and statistics

Get all nodejs processes

$ ps aux | grep dist/index

Reset the statistics by process signals

$ sudo kill -s SIGUSR1 <pid of node dist/index>

Run the application On Raspberry Pi At Startup

Running the application on boot:

sudo nano /etc/rc.local

On the line before exit 0 write the following script, replacing {path to application} with the directory of your application

su pi -c 'sudo npm start --prefix /home/pi/{path to application} < /dev/null &'

Write out the lines to save them (CTRL-X) and then $ sudo reboot to restart your RPi

Dashboard

The dashboard is an Ionic / React application that displays statistics and logs from the JsonBin.io log file. Please use the JsonBin ID configured in your Raspberry Pi Application.

Raspberry Pi Tree Watering System