The program plant.lua is ready now and can be downloaded from Sourceforge.
The Grove moisture sensor measures soil moisture and displays the measuring value on a LED bar. Furthermore the value is sent to dweet.io.
dweet.io is simple publishing and subscribing method for machines, sensors, devices, robots, and gadgets (name it things). Published messages are ‘dweets’. It’s helpful to think of dweet.io as a Twitter for things.
To visualize these data I use freeboard.io. You can understand freeboard.io as a ridiculously simple dashboard for IoT devices.
The image above shows such a dashboard for example. Each 30 seconds a new moisture value is sent to dweet.io and is visualized on the dashboard.
Clearly you can see the reduction of moisture over the time.
Similar program samples you will find in my book “Building an IoT Node for less than 15 $” expected at the end of November.