After testing the single modules for a sensor I finished the combination. Now the ESP8266 reads the temperature and humidity and sends them to the MQTT broker together with the actual voltage and the number of attempts to make a connection to the broker. The later is useful, because the ESP cannot reliably connect to the broker. I don’t know the reason, some investigation is necessary.
A photo and the circuit are in the earlier post.
As usual the code is on github.
After a lot of gambling around with a breadboard and afterwards soldering on a perfboard, I finished the first version of the sensor, which I want to spread in my flat. So the hardware is finished (for now – there are ideas for improvement). For the software I tested the individual parts.
Meanwhile I switched from RRDtool to gnuplot for the graphics. I didn’t understand the averaging in RRDtool completely, and I’m more comfortable with gnuplot.
The first step of my sensor network is completed. A BMP280 barometer sensor, a Raspberry Pi with an MQTT broker, a round robin database, an apache webserver and some Python and shell magic.