Automatic garden watering system

Table of contents

• General
• Running
  • Production
  • Testing without RPI
• .env
• Timeouts
• Debugging
• Installing from scratch

General

This project consists of a Raspberry Pi 4 that is connected to various floaters inside 2 water tanks and to various relays that control solenoid valves. Here's some specific info:

• Valves 1 - 4, 8 and 9 are for watering the garden
• Rain is a property set to define that it will or is currently raining for certain conditions to occur
• Tap water can be manually activated or deactivated, equals to Valve 5
• Pump is to manually activate or deactivate it, equals to Valve 6
• Letting water fall back down from tank 2 to 1 is done with Valve 7
• There are 5 floaters, three in the first tank and two in the second

GPIO pins are always written in BCM pin numbers.

GPIO pins also have a default state when booting the PI, which affects the temporary state of a relay switch until this project is running, which overwrites the default states to the desired ones. Here's a good read about it, as well as the technical file. In short:

HIGH for GPIOs up to 8, and LOW for GPIOs starting from 9.

On top of this, certain GPIO pins have special functions, and its best to not use those. So, after chatting with an AI, here are the supposed ideal GPIO pins:

Function	GPIO Pin	Notes	Physical Pin
Floater 1	GPIO 4	Input with pull-up	Pin 7
Floater 2	GPIO 17	Input with pull-up	Pin 11
Floater 3	GPIO 27	Input with pull-up	Pin 13
Floater 4	GPIO 22	Input with pull-up	Pin 15
Floater 5	GPIO 5	Input with pull-up	Pin 29
Valve 1	GPIO 26	Output, default LOW	Pin 37
Valve 2	GPIO 18	Output, default LOW	Pin 12
Valve 3	GPIO 23	Output, default LOW	Pin 16
Valve 4	GPIO 24	Output, default LOW	Pin 18
Tap water	GPIO 6	Output, default LOW	Pin 31
Pump water up	GPIO 13	Output, default LOW	Pin 33
Transfer water down	GPIO 19	Output, default LOW	Pin 35
Valve 8	GPIO 25	Output, default LOW	Pin 22
Valve 9	GPIO 20	Output, default LOW	Pin 38

Running

Production

Make sure the .env file is set to prod.

You need to run this with root. Else GPIO access won't be granted. I've configured pm2 to start the process on startup with sudo:

sudo -s
pm2 startup
pm2 start main.js --name "Watering System" --watch
pm2 save

Testing without RPI

Copy the .env file example below as is, execute npm i and then npm run start. Requires sudo apt-get install build-essential.

.env

Here's an example for the .env file:

WS_ENV=test
WS_PORT=3000
WS_MANUAL_TIMEOUT=28800000
WS_VALVE1_TIMEOUT=120000
WS_VALVE2_TIMEOUT=120000
WS_VALVE3_TIMEOUT=120000
WS_VALVE4_TIMEOUT=120000
WS_TAPWATER_TIMEOUT=172800000
WS_PUMP_TIMEOUT=1200000
WS_TRANSFER_TIMEOUT=1200000
WS_VALVE8_TIMEOUT=120000
WS_VALVE9_TIMEOUT=120000

Timeouts

Designation	Time	ms
Manual mode	8 hours	28800000
Valve 1	2 mins	120000
Valve 2	2 mins	120000
Valve 3	2 mins	120000
Valve 4	2 mins	120000
Tap water	48 hours	172800000
Pump	20 mins	1200000
Transfer	20 mins	1200000
Valve 8	2 mins	120000
Valve 9	2 mins	120000

Debugging

The PI sends a 3.3V current from the GPIO pins and is capable of measuring if a circuit is closed or not when the other end connects to Ground. The voltage is so minimal that you do not feel it on your hands, so it's safe to work with it. You should therefore be able to check the various connections of the floaters circuit for 3.3V (not the circuit after the relays, which is connected to 24V), and whenever a voltage doesn't make sense, you'd be closer to the source of the problem.

Installing from scratch

I had to create this guide, because I've lost too many hours trying to set things up from scratch more than once before. So here they are:

1. Use a RPI 4.
2. Use the Raspberry Pi Imager to create a bootable RPI micro SD card. Install the "Raspberry Pi OS Lite (64-bit)" image, based on "Debian Trixie".
3. Log into it, and first run sudo apt get update and sudo apt get upgrade --yes.
4. Install necessary tools: sudo apt install --yes git
5. Install nvm:
   1. Install Node version 16: nvm install lts/gallium
   2. Allow Node to be run in sudo (npm pigpio package requires sudo):

      n=$(which node)
      n=${n%/bin/node}
      chmod -R 755 $n/bin/* 
      sudo cp -r $n/{bin,lib,share} /usr/local 

6. Install pigpio (which requires some magic). GitHub user s-k-tttttttt made a great guide and script on how to set this up (big thanks!), so I will basically copy-paste their steps into here:
   1. sudo apt-get --yes --allow-change-held-packages install --no-install-recommends python3-setuptools python3-full
   2. wget https://github.com/joan2937/pigpio/archive/refs/tags/v79.tar.gz
   3. tar zxf v79.tar.gz
   4. cd pigpio-79
   5. make
   6. sudo make install
   7. sudo ldconfig
   8. TODO: I think from this point on, it should be enough. Test by running pigpiod -v. If a version comes out, you're good to go, and skip the rest of these sub-steps. You don't want the pigpiod service to be running, because the pigpio npm package will already be making that job, and refuse to start in case a daemon is already running.

   9. ---

   10. sudo systemctl daemon-reload
   11. Copy-paste this into your terminal (not into a file, it will create a new file for you):

       DOLLAR="\$"
       
       cat << EOF > config_pigpiod_service.sh
       #! /bin/bash
       PIGPIOD_SERVICE="/lib/systemd/system/pigpiod.service"
       
       if [[ ! -f "${DOLLAR}{PIGPIOD_SERVICE}" ]] ; then
       
         # The configuration of pigpiod appears to be different on 32 bit and 64 bit systems
         # pigpiod must be run with -t0 on a 64 bit system, and -t1 on a 32 bit system.
         # The 32 bit behaviour contradicts what is documented in the pigpiod web documentation ;-(
         ARCH=${DOLLAR}(uname -m)
       
         if [[ "${DOLLAR}{ARCH}" == "aarch64" ]] ; then
           T_COMMAND="-t0"
         elif [[ "${DOLLAR}{ARCH}" == "armv7l" ]] ; then
           T_COMMAND="-t1"
         elif [[ "${DOLLAR}{ARCH}" == "armv6l" ]] ; then
           T_COMMAND="-t1"
         else
           echo "uname -m returns '${DOLLAR}{ARCH}' which is an unexpected value. Time to debug..."
           echo
           echo "I have not seen armv8 on my Pi3, but I believe this might happen if running"
           echo "64 bits. I am not sure whether pigpiod requires -t0 or -t1 in this case."
           echo "You'll need to experiment."
           echo
           echo "I believe armv6 is a possibility on a Pi2 or earlier?"
           echo "I guess use same settings as for armv6l?"
           exit 1
         fi
       
         # We are going to overwrite the systemd configuration file for pigpiod
         # because we are going to change the launch options
         cat << END > "${DOLLAR}{PIGPIOD_SERVICE}"
       [Unit]
       Description=Daemon required to control GPIO pins via pigpio
       
       [Service]
       Type=forking
       ExecStart=/usr/local/bin/pigpiod -l -s10 ${DOLLAR}{T_COMMAND} -x0xFFFFFFF
       Restart=always
       ExecStop=/bin/systemctl kill pigpiod
       
       [Install]
       WantedBy=multi-user.target
       END
       else
         echo "${DOLLAR}{PIGPIOD_SERVICE} already exists. I refuse to change it."
       fi
       EOF
       
       chmod 755 config_pigpiod_service.sh

   12. Execute the newly created file: sudo ./config_pigpiod_service.sh.
   13. Start the daemon: sudo systemctl enable --now pigpiod.service.
   14. You can validate your installation was successful by running pigpiod -v.
7. Clone this repository.
8. cd into it and create a .env file with prod.
9. npm i.
10. Run sudo node main.js to check if everything works as expected.
11. Install pm2: sudo npm i -g pm2.
12. Start with pm2: sudo pm2 start main.js --name "Watering System" --watch.
13. Then make it run on boot: sudo pm2 startup && sudo pm2 save.