SlimmeLezer Ethernet

The ethernet modules have already been delivered and are ready to be mounted on the new ordered PCB’s. Those new PCB’s will probably be delivered within a day of 8-ish. So please be patience, there will be 100 on stock soon.

SlimmeLezer WiFi

Another batch of 600 has been ordered around 6th of July. With a bit of luck they’ll be ready within two weeks and than another day of 5 for shipping.

SlimmeLezer WiFi ESP32

I was experimenting with an ESP32-C3 begin 2022, yet the ESPHome code I couldn’t get properly working (I got it working, but not userfriendly to connect to your network). I soon realized that it probably was made too soon and has to be on hold until ESPHome is ready.

Therefore I made another prototype with the default ESP32-WROOM-32D. This one is fully compatible the way the “old” versions is working (the ESP12F). I even managed to squeeze it all on the same footprint as the regular version. So it fits in the current case as well. Now this ESP32 is a bit more expensive than the ESP12F, and I’m not sure if it’s worth the extra money in comparison to the functions.

The ESP12F is simple, cheap and does what it must do: send data from serial to wifi. Besides ESPHome, it also works with esp-link, for platforms that doesnt work with ESPHome. I haven’t found a working esp-link for either ESP32 or ESP32C3.

I wanted to use Improv via serial, yet that doesn’t work with the DSMR component. Improv requires a baud_rate higher than 0 under logger, while DSMR requires a baud_rate of 0 to work in hardware serial instead of software serial (see issue GitHub).

Using an ESP32 makes that possible, yet it draws more power (which probably can be tuned within ESPHome). It also makes it possible to use Improv via BLE (haven’t played with that yet).

So if there’s a demand/interest for this one, I could consider order it in larger batches, for now I’ve got about 15 as prototype (not sell worthy, unless you want to tinker with it).

New ESP32-based SlimmeLezer eth/wifi

An older prototype which I have since begin 2022, is a Wireless Tag WT32-ETH01 based reader. These developboards are sold for around โ‚ฌ15 on AliExpress or on Tinytronics. It’s an add-on board with integrated USB-serial to flash it (no usb on the developboard) and a P1 connector with inverter.

Because of the cost of those board, I might consider in only selling the custom PCB and you need to get a WT32-ETH01 yourself. I’ve looked in buying it in a large batch of 100 and that only saves you about โ‚ฌ2~โ‚ฌ3 and therefore not worth it in buying it large with a risk of not selling it.

It works without an external power source direct on my DSMR 5 test meter via ethernet. Via WiFi draws more power and I havent found the most stable setting yet.

This one is in my opinion the best solution for meters with encrypted data like in Luxembourg and Austria.

Another option is to add extra connectors for a water meter or solar panels (pulse counters). There’s some room left and I’m looking into that too.

I wonder what your thoughts are on these new prototypes ๐Ÿ™‚


  1. Simon

    In an ideal world?

    – ESP32 based
    – Ethernet
    – Powered by either P1 or PoE
    – 4 pin terminal block (2x gnd and 2x gpio) to interface witch two S0 pulse devices. With decoupling capacitor and fast switching protection diode in the signal paths.

    1. Marcel

      Ik heb er 30 liggen, dus ik kan er wat in de verkoop zetten ja ๐Ÿ™‚
      Toevallig heb ik ook een stuk of 10x WT32-ETH01 besteld, maar deze komen pas (AliExpress) in augustus binnen.
      Snelste is via de link van Tinytronics ๐Ÿ™‚

      1. Leon Vos

        Dat zou heel fijn zijn, ik heb zelf nog (17) esp32-eth-01 liggen (zonder header gesoldeerd) voor mijn led projecten.
        Als je dus een bordje kunt missen, graag.
        (ik heb zo’n P1 bordje van jouw, maar deze update niet via esphome ๐Ÿ™
        Gr Leon Vos


    Hello ,
    Do you have or plan to design P1 reader ethernet with POE (to reduce power failure risk)?
    Thanks a lot,

    1. Marcel

      Yes, but only an add on for the Olimex poe iso. Building a board myself wouldn’t be much cheaper, while these ESP32 PoE are already on the market. I might design it with a P1, two pulse readers and a relay on it (doorbell integration).

      1. Lennert

        This would be ideal: a P1 interface board for the Olimex POE with pulse counter interfaces (either through optical sensors or ‘direct’). But if I may request more then 2 please… ๐Ÿ™‚
        I have multiple energy meters in my ‘meterkast’:
        1. Solar production
        2. Heat Pump
        3. EV charging

  3. Wolfgang

    Hello Marcel,

    Nice work you are doing! I am located in Austria and would have interest in buying multiple ESP32-based SlimmeLezers and would use them with WiFi.

    Do you have any plan about when they are available – or as an alternative – when the current version of the SlimmeLezer+ is available again in the webshop?

    Best regards,

    1. Marcel

      The SlimmeLezer+ I will receive today, and probably be in the shop before end of the week. If you’re interested in the ESP32 models, I can sell you a few of my prototypes. They require power via USB as they’re drawing too much current, which the default DSMR5 can’t deliver (limited to 250mA). Send me a mail (webshop at zuidwijk) for further sales questions, as the prototypes aren’t in my store (yet)

      1. Vincent van der Sluis

        Ik heb geprobeerd contact via webshop@zuidwijk te nemen maar kreeg een email terug van een onjuist adres.
        Zou graag een prototype of werkend model ook overnemen van je .

  4. Sayan

    Eagerly waiting for SlimmeLezer+ WiFi or the ESP32-based SlimmeLezer eth/wifi
    I was about to buy the HomeWizard Wi-Fi P1 but fortunately discovered your product.
    Please let us know when I can order one of the SlimmeLezer on your site !

    Thanks !

    1. Marcel

      The normal ethernet is already on stock. The normal SlimmeLezer+ I’ll receive today (600 pieces). If you’re interested in the prototypes (ESP32 and ESP32-ethernet) than please email (webshop at zuidwijk) me, as I’ve got a dozen prototypes here ๐Ÿ˜‰

  5. Pierre

    I tried to validate an order but my adress seem to be a problem.

    How can I contact you ?

    Thanks in advance.

    1. Marcel

      You should have received an order confirmation. You can reply to that. Or send an email to webshop at zuidwijk ๐Ÿ™‚

    1. Marcel

      What I’ve read so far, is that it has the same p1 connector and possibly the same way of reading it … If someone has a warmtelink, we could test something …
      It seems like a default USB cable can read data, so it all comes down to converting the telegrams to supported data (not sure if HA supports it already…)

      1. Artem

        I’ll be moving to an apartment with Warmtelink in a month so if there is a way to dump raw telegrams from the SlimmeLezer+ I should be able to do that.

  6. Alexandre

    Argh, don’t tempt me with this one now that I have a P10 reader (but requiring smartmeter2mqtt to decrypt Luxembourg meter) and a Slimmelezer+ ๐Ÿ™‚
    In my case, I wouldn’t need POE, but I would suggest chips working with IPv4 and IPv6.
    I know IPv4 is sufficient for a LAN, but think of a WAN, when the provider does not provide a private IPv4; IPv6 is then the only solution to reach the device directly from the internet.
    Anyway, enjoy your holidays.

  7. Kristian Kรถhntopp

    Marcel, I am using your P1 Reader with Ethernet and it works fine and out of the box. I am collecting P1 data and pushing it into a Mosquitto -> Influx -> Grafana to collect my Gas and Power consumption data.

    Sometimes the reader crashes, though, and then I have to walk down to the wallbox and manually powercycle it.

    Is there a way to remotely force the thing to reboot every 24h, or is there a mode that can be set where it will simply restart itself every 24h?

    1. Marcel

      Hi this is a thing I’m still figuring out. I had exact the same thing a few years ago (sometimes 2x a day, sometimes 1x a week). Without doing anything, still same config and same hardware, no more issues since last 2+ years. I’ve asked the manufacture for a software fix. Something like a watchdog function. A hardware reset once the gateway isnt pingable for a defined period of time. Unfortunately they wont do that. I’m searching for another way to fix that. This happens on les than 1% of the devices. And I’m not sure what exactly causes this. It might be that there is a buffer overflow… its known that sometimes the meter sends a field (not used) with a too large data part in that. Still, a buffer overflow shouldn’t be happening, as the device should drop that package. Still in research…

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