Clearing The Air About Proprietary Consumables With A Xiaomi Filter DRM Resetter

100% display from filter screen and the responsible mod chip

The “razor and blades model” probably set a lot of young hackers on their current trajectory. If we buy a widget, we want to pick our widget refills instead of going back to the manufacturer for their name-brand option. [Flamingo-Tech] was having none of it when they needed a new filter for their Xiaomi air purifier so they set out to fool it into thinking there was a genuine replacement fresh from the box. Unlike a razor handle, the air purifier can refuse to work if it is not happy, so the best option was to make a “mod-chip.”

The manufacturer’s filters have a Near-Field Communication (NFC) chip and antenna which talk to the base station. The controller receives the filter data via I2C, but the mod-chip replaces that transmitter and reassures the controller that everything is peachy in filter town. On top of the obvious hack here, [Flamingo-Tech] shows us how to extend filter life with inexpensive wraps, so that’s a twofer. You can create your own mod-chip from the open-source files or grab one from [Flamingo-Tech’s] Tindie store.

We usually hear about mod-chips in relation to games, but we are happy to extend that honor to 3D printers. Have you ever fooled a “razor?”

Thank you, [The_mad_ping], for the tip.

16 thoughts on “Clearing The Air About Proprietary Consumables With A Xiaomi Filter DRM Resetter

  1. Wouldn’t it be cheaper to 3D print an adapter to connect a replacement filter to a common computer fan or is it one of those cases where a complete unit only costs a small amount more than the replacement filter?

    1. for awhile we were buying cheap printers on sale, run it till the ink ran out and then buy another printer. because it was cheaper than buying ink. the inkjet model can be taken way too far and create a bigger problem in the long run.

        1. Same here, I buy toner powder and fill the original cartridges, My Brother even has a filling opening in the cartridges for this, and you can reset the cartridge via the printer menu.

  2. Anyone see Xiaomi issuing a take-down notice of some sort? [Flamingo-Tech] the manufacturer of the mod-chip is based in the Netherlands.[1] So [Flamingo-Tech] would be probably be subject to the EU/Dutch equivalent of the U.S.’s Digital Millennium Copyright Act (DMCA). Tindie is U.S.-based even though Tindie is owned by Supplyframe (owner of Hackaday) who in-turn is owned by Siemans. As-such Xiaomi could conceivably issue Tindie a U.S. DMCA take-down notice.

    But the case law regarding DMCA use against durable goods where the manufacturer makes little or no effort to protect the means of its lock scheme (the I2C stream in this case) is not good.[2] Regardless, Xiaomi can issue the take-down anyway and bludgeon Tindie with greedy-aggressive Trial Lawyers to force Tindie to relent and remove the mod-chip from its marketplace.

    Rather than issuing take-down notices, I think it would be better for Xiaomi to spend its time and resources modifying its lock scheme to render the mod-chip useless. Maybe use a rolling or hopping code to prevent a replay attack, which is essentially what the mod-chip does.

    1. “How are are the modchips made: all modchips are hand assembled and soldered in the Netherlands, and tested before shipping!”

    2. Digital Millennium Copyright Act (DMCA) – Durable goods case law – “Lexmark International, Inc. v. Static Control Components, Inc.”

  3. The subject matter is great, but I also want to say that this is the best-written article I’ve read here in a while and that’s not a knock against any of the others. Made me smile. Thanks Brian!

  4. Hi all,

    Disclaimer: I made/designed this device!

    First @Brian, Thank you for the article, I’m a long time HaD reader and it makes me proud to be featured here! (Great work on the article!)

    This model works on the 3H and the Pro versions of the Xiaomi air purifiers. (currently I’m working on adding the 2S to the list aswell)

    @Drone: It’s just a way to weaponize the legal system.. again.. It would surprise me if they would do this is since this is more a thing of big western companies.
    we actually had a similar case here. HP & Samsung lost :

    happy hacking!

  5. It’s a simple air filter. If I had one of these I would yank the electronic garbage out of the stupid thing and build a simple power supply to make the fan run.

    These stupid companies won’t spend a penny on higher quality components, but I bet they spent millions on that asinine DRM crap. Jerks.

  6. Reminds me of the CatGenie 120 mods. On the original, you could reprogram the cartridges directly, but the 120 introduced NFC like what’s mentioned here. The NFC chips had counters that could not be programmed to go up, only down. So the solution was to replace the NFC chip and spoof its operations over I2C, same as here.

    1. Cartridges that held cents worth of sanitizer used in any food service third sink, but are expensive. The hacks leave you with a tank of refillable cheap sanitizer.

      Yes, we’re talking about a cat toilet with a cold water line and drain hose.

  7. Am I missing something, but the filter needs no resetting whatever. Sure, it’s convenient to track how much filter life is left with nfc, but it just continues to run when the filter reaches 0 percent. If you’re still conserned, just take off the nfc sticker (that can be used as a tag for another project), press the filter reset button and it just works.
    Stone filters manufactured by non-xiaomi have no stickers whatsoever. And there is no problem using those.

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