If you got here then probably because you are in the same situation that I was. You bought these thermostats because they look really nice, in particular together with other Livolo switches and sockets. Then you figured out that they have many issues:
Probably the easiest solution would be just to get other thermostats but if you bought already several of them and you using other Livolo switches there is no suitable replacement, which would look good and fit into the 40x40mm. Therefore, I started thinking about modifying it and considered writing a new firmware.
You can find a detailed description of the hardware and circuit on the Hardware Description page
The first thing I started to think about was taking the sensor out of the housing to get a better measurement. Fortunately, the thermometer is a standard DS18B20 chip, so I got the SMD version and soldered it on a copper plate for taking the temperature of the environment. (The temperature is measured on the ground pin by the way). Before I bent the pin 1 (DQ) and pin 8 (Vdd) up in order to connect the cable.
My new firmware also supports the so-called "parasite power mode", which only requires two wires. So you can connect pin 8 also to ground, together with all others. That makes it a little bit easier to build.
This new sensor replaces then the internal sensor beneath the airflow holes. However, this alone did not lead to much improvement. Now the temperature displayed was too low.
Finally, I came to the point of considering the effort to write a new firmware. Fortunately, the PIC16F690 controller is very well documented and I have a lot of experience in 8-bit assembly programming. This controller supports in-circuit programming and luckily, the board has the connections for the programmer. Nevertheless, I would not solder a connector there, as the pins might scratch the display and you would see them as some dots in the display. The better option is just soldering temporarily the 5 wires directly to it. As the controller has the copy protect bit set, I had to start from scratch.
For programming, I used the PICkit 3 programmer, which is pretty inexpensive.
The final firmware now has these new features:
For my bedroom, I wanted the display to turn off automatically in the darkness. Therefore, I considered also adding a light sensor. There is another DS18B20 thermometer inside, which is not really useful, so we can use this pin for it. Unfortunately pin 8 (RB6) cannot be configure as A/D converter input, so I connected the external thermometer to this pin and the photo resistor to pin 10 (RB4), which can be used for the ADC. My firmware detects the thermometer automatically. Therefore, you may or may not do this mod.
1.0 Initial release
1.1 Functional enhancements
1.2 Functional enhancements and major rework
Hardware description
Hardware modifications
Firmware update
User mannual