After a couple of nights tinkering ,PCBA designing , software writing and a couple of PCBA revisions later success: (see GIF , above)
Using these air purifiers is a wasteful and expensive experience. There are no third party filters on the market , and no options to disable the NFC check.
I wanted to use these filter cloths around my filters:
These filter cloths will extend the life of the filter by 2-3 times and will be less wasteful for the environment. These cloths can be bought for 3-4 USD for 10 Pcs.
How does it work:
By probing around on the bus (I2C) that is used by the NFC chip and the main microcontroller we could identify how these filters work. I was able to Emulate the NFC IC within an STM32 microcontroller and fooling the system that a 100% new filter is installed.
Im planning of distributing these modchips trough friends.
Does this void the XIAOMI warranty: YES
Is it undetectable by XIAMI: YES (for now, if they are smart , and update their software they might find a workaround)
Do i lose any of the functionally when i use this modchip: NO, everything will work fine.
Is it easy to install: YES (10 screws and you are done)
Where can i find an installation manual: https://flamingo-tech.nl/2021/06/30/how-to-install-xiaomi-air-purifier-mod-chip-to-your-3h-3c-or-pro-device/
It’s open source: https://flamingo-tech.nl/2021/07/10/xiaomi-modchip-open-source/
Special Thanks to DER_T, Tuxuser and Koelie