This is a tiny case to house an ESP32 module, a soil moisture sensor, and a tiny OLED display to stick into your indoor plants for monitoring soil moisture levels. With an installed ESPHome script, the sensor values can be reported into Home Assistant for you to create automations using its values. Imagine your plants telling you when they're thirsty!

Assembly:

• Print all 5 parts with your favorite PLA or other filament
• Solder a shortened piece of the soil moisture sensor's connector to the ESP board. I'm using ground, 3.3V, and IO34 (ADC) pins from one side of the ESP board
• Cut about 2" section of 4 different color 24 gauge wire. Solder these to ground, VCC, IO21, and IO22 pins on the opposite side of the board
• Insert your OLED screen into the OLED carriage with the screen facing upward. Wiring will be inserted into the back of the screen and soldered on top. Solder the ground, VCC, IO22, IO21 pins (in that order L-R) onto the OLED screen
• Insert the ESP board into its carriage and insert the assembly into the back cover
• Lay the soil moisture sensor in its place next, ensuring that the screw cutouts align with the screw holes on the back cover
• Feed the OLED screen and carriage through the spacer carriage and slide the spacer all the way down into the back cover above the ESP carriage assembly
• Insert the OLED screen assembly into the top cover opening and place the top cover onto the bottom cover. It should catch on the uppermost position further from the screw holes.
• Insert M3x16 screws into the top cover and screw them all the way down

Installation:

• Open ESPHome and add a new board
• Copy the contents of the included sensor.txt file into the generated configuration file in ESPHome (append to the bottom, do not overwrite the defaults as this will lose your encryption key)
• Install the configuration file onto the ESP board.
• You should now see details on the OLED screen for the plant name, computed sensor value, and an MDI icon representing the happiness of the plant.

Home Assistant:

• If everything worked well above, Home Assistant should tell you that it found a new sensor. Go into Settings → Devices and configure the sensor. For this step, you will need the encryption key from your auto-generated ESPHome configuration file

As with any project requiring mains power, please use extreme caution while testing. I am not responsible for any damage to your electronics.

Amazon Links for electronics that I used for this project:

D1 Mini ESP-32 boards: https://amzn.to/3Pu6R4a
Micro USB cable 4-pack: https://amzn.to/3VL5SR6
Capacitive Soil Moisture Sensors: https://amzn.to/4aGNoFP
24 Gauge electrical wire: https://amzn.to/4cDu2mR
6-port USB Charging Station: https://amzn.to/3vHgoyh
I2C OLED Display: https://amzn.to/4chg2it

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