Measure and log 6 parameters of a heating boiler. Works as client/server, communicates via WLAN. ESP8266 plus 429 Disco board.

If you want to optimize a heating system, you have to collect a lot of information at the very beginning. The target of this development is to measure some important parameters of a heating boiler and store all the collected data on a USB stick for further analysis, e.g. with Excel.

The following boiler values are gathered:
    Forward temperature of heating water
    Return temperature of heating water
    Temperature of outside environment
    Hot water temperature
    Hot water heating temperature
    Burner on/off time

Solution overview
The technical solution is based on a client/server approach, the connection between server and client runs via WLAN. The measurement of the data is performed by the server, which is equipped with an ESP8266 in a standalone mode. A model ESP 201 with a lot of GPIO pins has five sensors DS18B20 in order to fetch the temperature values. The burner activities are monitored by a microphone, because there should be no connection with the electrical power of the heating boiler. The firmware of the server acts as station with a TCP server, which sends periodically the measured data via WLAN to the client.

The logging part has two components: An ESP8266, which receives the data and delivers it to a STM32F429 Discovery board. The ESP client is configured as station and logs into the TCP server of the measurement system. It is connected with the Disco board via RX/TX lines. In order to have always the proper time and date, the client opens periodically an Internet connection to a NTP-service (PTB Braunschweig) and sets the RTC of the Disco board.

The touch panel of the Disco is used to display the actual values. As software the STemWin library is in use. This lib is very powerful, it could e.g. draw lines and diagrams, but these functions are not used in this first release. For further analysis, the data is written on an USB stick, which is formatted with FAT32. For every day, from 00.00 until 23.59 o´clock a file is created and gets for every minute one record with all the data. The txt-format of the file can be easily imported into Excel and all numerical and graphical analysis can be done.

The following tools have to be used:
On Disco board: CooCox 1.76
On ESP8266: Eclipse Mars
Language: C
STemWin: Segger and STM
Utilities: Uwe Becker

This solution runs since several months very stable and without errors in my house. Some pictures, the schematics and the firmware projects are included.
Have fun with your developments!