nodeMCU based moisture monitoring for plants
🌱with a serverless backend
- Collect sensor readings every 5 minutes
- Submit values to serverless infrastructure using local WiFi network
- Automatically fetch weather report for each reading using backend function
- later have a UI as well
The hardware setup consists of a ESP8266 Microcontroller with a powersupply and two connected sensors.
- DHT22 connected to D2 digital input pin
- Soil moisture sensor connected to A0
- Bridge between D0 and RST to enable deep sleep for optimizing battery life
- switch off sensors during deepsleep using a transistor driven via pin D1
To program the ESP8266 you need to clear the connection to RST
- ESP8266 draws
~80mAwhen active and few
µAwhen in deepsleep
- Maximum output current per GPIO pin is
- Photo resistor has
3V3 / 10kOhm = 33mA
- Moisture sensor consumes
- DHT222 max current
The ESP8266 chip is programmed with the esp8266.ino file using the Arduino IDE. Secrets for connecting to local WiFi and endpoints to post data need to be defined in a
esp8266.secrets.c file which is specified at esp8266.secrets.template.c.
As a backend solution the plantbuddy runs on Google's firebase
- Firestore database to store all sensor readings and heartbeats
- Firebase functions for providing an HTTP endpoint as well as querying for weather data for each sensor reading
Note: As outbound traffic is required to collect weather data, the project should run in BLAZE plan. Function and database usage should be within the free tier, only outbound traffic will be billed.
Before deploying the backend code several variables need to be set so the service can work correctly. An API token for OpenWeatherMap can be obtained from their website. A free account should suffice unless a LOT of plantbuddies are running on one account.
firebase functions:config:set owm.key=<OpenWeatherMap API Token> firebase functions:config:set owm.city_id=2873776 // according to [OWM City ID List](https://openweathermap.org/current#cityid) firebase functions:config:set header.secret=<some secret>
For devleoping the function locally:
# get a copy of the environment config firebase functions:config:get > functions/.runtimeconfig.json # start function host locally firebase serve --only functions
All the Firebase stuff gets automatically deployed via Travis CI. To set it up create a encrypted token and update the Travis CI Config.
# create a firebase CI token firebase login:ci # encrypt the token to your project docker run --rm caktux/travis-cli encrypt "<token from firebase login:ci>" -r anoff/plantbuddy