ESP32 Powered Smart Plant Monitor

Description

Have you ever wanted to monitor the soil humidity of your plants? If yes, you probably have already tried many of the cheap modules available on many sites and noticed that after only a month or two in the soil they corrode like crazy.

Then what? They are thrown away in the trash ...

Some capacitive modules have a longer life however they are still so inacurate, cannot be calibrated and when they eventually die too. What a waste!

The Smart Plant Monitor (a monitor for smart plants) takes advantage of the ESP32-S3's touchpad feature which has all the circuitry needed to monitor capacitance. Pair that with a cheap, replaceable soil probe (or even just stick a copper wire in the ground!) and you got yourself a nice little device that can reliably measure capacitance.

More than that, this module can be reused for and combined with any other projects, thus reducing the number of components you need.

Details

Overall features:

Low power and small size (45x45x10mm)
Rechargeable and programable with Arduino
By adding a USB port to a small solar panel you've created a simple add-on
Can communicate via WIFI or Bluetooth
One device can stay plugged in all the time (act as hub) while the others send updates to it (low power mode)

Back of the main board. Features:

ESP32-S3 supports capacitance measuring directly, through the touchpad circuitry
TP4056 charging + protection circuit
USB C with 5.1K resistors added
3.3V LDO for powering everything
Circuitry for a 1.54" E-Paper display (goes on the back)
AHT20 IC for local air humidity and temperature measurement
Card edge connector for easy and cheap "soil probe" PCB swap
2 GPIO buttons (one connected to GPIO0) and 1 status LED

Front of the main board. Features:

Battery on-off switch
I2C header for possible module addition
E-Paper display
Slim LiPo battery goes under the display. Could fit up to 4x40x30mm (usually 450-500mAh)

Soil probe. Features:

No components and connectors added, just the bare PCB
Cheap and easy to replace when they eventually breakdown in the soil
Solder pads avaialble if you'd like to add a 0603 component (LED or Thermistor for soil surface temperature). Connected to GPIO through a 2K resistor
Can be in any size and shape you'd like as long as the top matches the conector (calibration and adjustments are done in software)

Files

Schematic_Plant Monitor SMD.png

High level schematic

Portable Network Graphics (PNG) - 290.25 kB - 06/21/2023 at 08:16

Preview

Gerber_PCB_Plant Monitor SMD.zip

Gerber file that can be used to directly order the main PCB from any manufacturing site you'd like

x-zip-compressed - 189.31 kB - 06/21/2023 at 08:16

Download

Gerber_Probe Small.zip

Gerber file that can be used to directly order the small soil probe PCB from any manufacturing site you'd like

x-zip-compressed - 6.51 kB - 06/21/2023 at 08:16

Download

BOM_Plant Monitor SMD V2.csv

Bill of Materials for the main PCB (for 1 PCB)

Comma-Separated Values - 5.57 kB - 06/21/2023 at 08:16

Download

Gerber_Probe.zip

Gerber file that can be used to directly order the large soil probe PCB from any manufacturing site you'd like

x-zip-compressed - 6.58 kB - 06/21/2023 at 08:16

Download

Components

1 × Custom PCB board For design files and detailed build instructions please check the files section

1 × Custom case For design files and detailed build instructions please check the files section

1 × (Optional) Custom capacitive soil probe For design files and detailed build instructions please check the files section

1 × 3.7V Li-Po battery 500mAh (size: 502534)

1 × (Optional) 10K NTC with connector

Project Logs

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Added support for Friendly Name

Ovidiu • 07/03/2023 at 11:03 • 0 comments

In order to be able to easily distinguish between multiple devices i have added support to give each one a "Friendly Name".

This will be used in Home Assistant instead of the hostname

Created a small solar charger "module" to extend the battery life

Ovidiu • 06/29/2023 at 10:27 • 0 comments

This project was optimized so that even a tiny 500mAh battery would last for more than 2 weeks while sending updates over WIFI every 30 min!

With this simple add-on module the battery will slowly recharge over time while maintaining the entire project small and compact

Build Instructions

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Build the Main PCB

Feel free to use the ready-made gerber files from my github to order a complete assebled PCB from your favorite site

Here are the files: https://github.com/ovidiu4/smart-plant-monitor/tree/main/hardware

(Optional) Build the soil probe PCB

Feel free to use the ready-made gerber files from my github to order a bunch of soil probe PCBs

https://github.com/ovidiu4/smart-plant-monitor/tree/main/hardware

If you'd like to skip this step just know that capacitance can be measures with just a single wire!

Experiment with some dupont wires :)

(Optional) 3D print the case

Feel free to use the ready-made STL files from my github to order or 3D your case

https://github.com/ovidiu4/smart-plant-monitor/tree/main/case

Discussions

ESP32 Powered Smart Plant Monitor

Description

Details