By Jon Archer
As part of my interest in aquaponics I’ve always intended to enable some kind of electronic monitoring, various thoughts on what to monitor and how have been in my head for a while. Recently I’ve been wondering if the temperature levels of the water are high enough so this was as good a place as any to start.
An Arduino was my obvious choice to start with, I built various circuits but soon decided that I wouldn’t be running Ethernet anywhere near and that kind of ruled it out with regards to re-using existing kit. I decided to use one of the nodeMCU devices I’m halfway through a project on (I’ll just buy another couple eventually).
Having previously used LUA script on the devices, I decided to use the Arduino method instead this time, mainly to investigate the OTA options now available. I’d already built up some perf board based shields to house a connector to a DS18B20 temperature sensor, so I just added some female headers to one of the waterproof sensors I have lying around and hey presto.
I have power near the tank so I’ve opted for an always on solution with a permanent supply, rather than power from batteries and have to worry about charge cycles. WiFi connection works perfectly outdoors too.
I will be publishing the sketch on GitHub shortly (watch here for an edit), just need to tidy up a little. But essentially it reads the temp every 10 seconds and publishes to an MQTT topic, fairly simple for now but I do plan on adding more sensors for humidity, greenhouse temperature and possibly others such as luminosity and maybe barometric pressure and pH. For now though I have enough to get me going and also have the data of interest.
The data itself just goes to an MQTT stream, but I’ve developed a simple web front end using jquery to show a simple gauge. I have also used the script at https://github.com/irvined1982/MQTT2RRD to generate rrd information to form rrd graphs which can actually be seen in the sidebar on this site.
Great data for now.
Here’s a couple of pics of the device and the probe in the water.