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Toby, a wifi plant watering sensor system with a difference!

Published on 5 June 2020 at 17:22

Toby, a wifi plant monitoring system

You've probably worked hard to grow beautiful houseplants with a consistent watering schedule. But if you head out on vacation, you don't want your plants to suffer. So you ask your friendly neighbor to water your plants. But how does he or she know when a particular plant needs water?  That's why we developed Toby, our wifi plant watering sensor system: to help that neighbor or remind you when your plants needs watering.  And I can tell you, forgetful as I am, my plants never looked better!

What do you need for a plant watering sensor system?
A minimum set consists of a few battery powered plant watering sensors and a central hub to gather the data of the sensors and notify you when one of the plants needs watering.

Plant watering sensor

We didn't want the sensors limited to measuring the soil moisture, so we added a temperature, humidity and ambient light sensors. To let the sensors talk to the hub we needed wireless communication. We have tried several wireless radio systems and decided to go for Wifi. A lot of devices in your environment can communicate via Wifi and with Wifi you can connect to the whole world.  The sensors needed to be battery powered and last for at least 6 months. This was accomplished by letting the sensors sleep most of the time and only wake up when they need to do measurements and send data via Wifi to the the hub.

When you Google 'plant watering sensor' you will find that a default shape for the enclosure of this type of sensors has emerged: an oval, flattened egg-like shape. We decided that was good enough so we used that for the enclosure. But what if your plant or pot is not that big? You don't want a big sensor sticking out like a sore thumb! So we designed another smaller sensor with a 3-core wire that connects to a battery powered, microcontroller-driven Wifi radio. That way you can keep the  Wifi radio device hidden behind the plant pot. 

The hub
You also need an intelligent hub to gather the data of the plant watering sensors and notify you in some manner when one of the plants need watering. In the last couple of months we gained more experience in 3d design with Fusion 360. So we decided to put our skills to the test and design a friendly enclosure for the hub with an inviting look that would put a smile on your face. And we didn't want a simple buzzer or a blinking light, we wanted the hub to talk to us! That meant Text-To-Speech.
Listen to a sample of Toby telling you to water the roses in the living room:

After a brainstorm session we had the following requirements:

  • Stereo Audio capability
  • 2 speakers
  • Volume potentiometer
  • Single Board Computer
  • Linux-based Operation System
  • OLED display
  • Fancy enclosure
  • Powered by 5V USB adapter with micro USB connector
  • Fully customizable by makers!

We worked hard on this project and after a few months we came up with this set:

Last year we developed Sniffy, an educational Wifi IoT sensor. Sniffy uses HTTP GET commands to connect to a server. Source code is available. It doesn't take much effort to change the url and connect to Toby.

As I said, Toby is fully customizable. It uses Node-Red, a visual programming tool to process events. Node-Red is very intuitive and easy to use.

We hope you like Toby!



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