Introduction

This project is meant to keep my plants healthy while I go on vacations.

Part 1 - Prototype

Parts required

  • Raspberry Pi Zero (will work with any Raspberry Pi)
  • micro usb power supply
  • 3v-5v pump
  • small hose for the pump
  • 5v relay
  • wires

Wiring diagram

Pump scheme

Relay inputs:

  • NO = normally opened
  • NC = normally closed
  • CO = common
  • DC- = ground
  • DC+ = 5V signal
  • IN = signal

Code

Simple python code to send a signal to pin 8 for 0.8 seconds which, in our case, will open the pump and water the plant.

from time import sleep
import RPI.GPIO as GPIO

GPIO.setmode(GPIO.BOARD)
GPIO.setup(8, GPIO.OUT)

GPIO.output(8, GPIO.HIGH)
sleep(0.8)
GPIO.output(8, GPIO.LOW)

GPIO.cleanup()

Using linux cron jobs we can run the above program on a schedule:

  • run crontab -e command in the terminal
  • at the bottom of the file write the following line which will run water.py at 10:00 AM on Monday, Wednesday, Friday, and Saturday:
0 10 * * 1,3,5,6 python ~/projects/water.py

Final result

Final result

Syphon

One of the challenges I faced was the continued flow of water through the hose even after switching off the pump. The solution I came out with was to elevate the flower pot on a bowl so the end of the hose is higher and the syphon can’t form.

Part 2 - Raspberry Pi Pico

A linux computer like the Raspberry Pi Zero used in the prototype is overkill for this application and a more suitable candidate is a microcontroller like the Raspberry Pi Pico.

Wiring diagram

Pump scheme

Code

I used Arduino IDE to write a simple program that will open the pump for 10 seconds every 2 days.

const unsigned long SECOND = 1000;
const unsigned long MINUTE = SECOND * 60;
const unsigned long HOUR = MINUTE * 60;
const unsigned long DAY = HOUR * 24;

int pin = 16;

void setup() {
  pinMode(pin, OUTPUT);

}

void loop() {
  openPump();
  delay(2 * DAY);                    
}

void openPump() {
  digitalWrite(pin, HIGH);
  delay(10 * SECOND);
  digitalWrite(pin, LOW);
}

Result

Respberry pi pico wired

Part 3 - Multiple plants

In order to water multiple plants I designed and 3d printed a simple T-shape connector: t-connector

I could have just made a hole in the hose for each pot but this is a bit more elegant solution. Flowers

Part 4 - Improving the code

While Arduino studio is awesome, it didn’t seem to have the best support for the Raspberry Pi Pico. The recommended languages for the Pico are C++ and Python and I decided to go with Python.

I rewrite the code in Python and did the following improvements:

  • connect the board to wi-fi
  • get the time from a NTP(Network Time Protocol) server
  • open the pump every two days at 12:00

Check the github repo for the code.