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Reverse engineering the Essent E-thermostaat

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So, what’s next?

As the code can of course be read from the flash itself (the program needs to have access to itself), it crossed my mind to develop a bootloader which dumps the rest of the flash memory. This would ofcourse wipe the existing bootloader in the chip, so the chances of ending up with a defective product are pretty high.

Another thing which could be interesting, is to disassemble the base station. Maybe there is some firmware in there as well? Or is it just a ‘dumb’ extension of the thermostat?

For now, this was the end of my journey. At the moment of writing this article, it still isn’t February so I will enjoy a working thermostat while I still can.

Thank you for staying with me along this journey. I hope you learned just as much from it as I did. Even though it was unsuccesful in the end, the journey was really interesting and learned me a lot. If you have some things I might try in the future, please let me know.

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9 thoughts on “Reverse engineering the Essent E-thermostaat”

  1. Enjoyed reading your article, too bad you didn’t succeed.
    I will check back later to see if you see if any progress has been made.
    In the worst case,. I have disposed of my e-thermostaat and help is too late for me

    1. Thanks for your response. For now I paid the 24 Euros so I can use the thermostat for at least another year. So probably no updates from my side, but if so I’ll let you know.

  2. Maybe it is possible to read the thermostat thermometer and rig the + and – button so you can control it with an Arduino or Pi Zero? Or even a step further, connect said Arduino or Pi to read the data that is going to the LCD?

    1. That’s probably feasible, however I doubt if that would be much less work than designing my own thermostat and letting my home automation system control it. If you already go the extra mile to get an additional device such as Arduino or Pi to read the pins, switching a relay and reading a temperature sensor is not that much work either though.

  3. I wonder if you were able to make any progress. The next year (for prolongate the subscription) is coming.
    I’m asking myself if it couldn’t be better to design an open source thermostat. But I also agree that another €23,40 shouldn’t be the problem.

    1. In the end I did design a very simple ESP8266 thermostat which communicates via SSL to my MQTT server. I can control it with my Home Assistant installation. It’s been working okay but because it sometimes crashes and I have to manually repower it, I haven’t released it yet. It’s designed to always fail safely so the heating turns off so it’s no big deal but it’s not ready to release.

      At the moment I am also considering flashing Tasmota, which I use for some of my lights. I think that is a better option.

      So to answer your question: no progress with this project and I probably never will. The thermostat was never perfect in the first place.

  4. Hi, thanks for this read! It’s a few years later now, and I was wondering if you ever did an attempt to try things out with the base station?

    1. Hi Robert, no I did not. This Essent E-thermostaat ship has sailed for me. I have moved in the meantime and am running a heat pump system now, so I have little need to control my thermostat remote anymore.

  5. Last week I tried to dump the firmware of the device using a PicKit2 programmer. After connecting succesfully, and giving the “read” command, the software says “Code protect”. So indead the PIC is read-protected 🙁

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