Basic Monitor Nodes My basic monitor node uses an IComSat GSM / GPRS SIM900 Module Expansion Board Shield on an Arduino Uno to send send an SMS when my veggies need to be watered.
The node monitors the soil moisture using two nails embedded in plaster of paris, by testing the resistance between the nails an indication of the moisture content is obtained.
Basic Smart Nodes The basic smart node is an ESP8266 that monitors soil moisture in seedling trays using a “Soil Moisture Sensor”. A web server implemented on the ESP8266 sends an alert webpage when the soil is getting too dry.
The basic smart node will be powered by a small solar cell allowing placement anywhere in the garden.
The “Control Centre” will be a modified “Basic Monitor Node” that will collate then send (and receive) data over the internet using a GSM / GPRS Module such as the “GSM / GPRS SIM900 Module Expansion Board Shield”, if access to the internet can not be gained directly (wire) or wirelessly (eg a wireless router).
Data receive may be used to configure or control the “Garden stations” and/or the “Smart Nodes”.
A “Garden station” will have provision for a wide range of sensors eg air temperature, barometric pressure, humidity, rain, wind speed, evaporation, etc.
Using a Stevensons enclosure to house the sensors, like the BME280 (air temperature, barometric pressure, and humidity), such as one of the designs on Thingiverse will improve the accuracy of the measurements.
While some designs on Thingiverse for rain gauges and anemometers are interesting most so far need more improvement.
The smart nodes use ESP8266 in mesh mode to ensure that data can get to and from all nodes in a large community garden.