Monitoring swimming pool with mqopen

One of the most common sensors is Dallas DS18B20 temperature sensor. It is pretty cheap, accurate, has only one data wire and is available in water-proof package. mqopen has already support for DS18B20, so building simple temperature sensor is really easy.

It comes handy at the start of the summer for monitoring water temperature in a swimming pool. I built a probe very similar to this one, except with water-resistant cable join.

Sensor itself is placed at the bottom of the swimming pool where the water temperature is lowest. Other end of the probe is plugged in ESP8266 node under little roof, protected against rain.

Sensor periodically reads water temperature and sends it to my MQTT network. mqspeak then collect the data and updates ThingSpeak channel with actual water temperature. Final graph (from rainy day) looks like this:

ESP8266 node firmware update

I made some progress on my ESP8266 node firmware. My goal is to build single, robust, configurable and reliable piece of code for these little IoT devices, to avoid redundant implementations and unnecessary bugs. You can download it from my GitHub. Users should be able to configure it in kconfig interface and create firmware their own IoT device without need to write single line of code or even modifying any header file.

List of esp8266-node updates:

• Added service topics - I added various service MQTT topics which node sends into network when it connects. This is useful for statistics purposes. debugging or for searching nodes with obsolete firmware or hardware versions.
• Device class - I divided nodes into two basic classes:
  • Sensor - Sensor device sends data to network.
  • Reactor - Reactor devices reacts to data from sensors and take some actions. I have already implemented some prototype code, but this part is in the main development.
• Asynchronous sensors - I implemented abstraction layer for synchronous and asynchronous sensors. Synchronous sensor periodically sends data. Asynchronous ones waits for some event and sends data only when event happens (with retain bit set). This feature takes advantage of MQTT to save bandwith and improve response time for a other devices. I'm building a door sensor which reports every time when door status changes (open / closed).
• Initial data publish - Nature of asynchronous sensor it that it sends data only when event happens. I implemented logic which sends sensor state when node becomes online, if the state is relevant.
• Various bug fixes - I fixed some bugs in the code and hopefully improved device reliability.

I have lot of ideas for another improvements, stay tuned :) http://mqopen.org