Reverse Engineering A Very Low-cost Health Band

With the advent of well-known smartwatches on the market, there are also a few lower-priced offerings. The M6 ​​fitness band is one of them and [Raphael] set out to hack the cheap device with a custom firmware he had created himself.

The M6 ​​band, which sells for around $ 6, appears to be trading on name resemblance to the more expensive (~ $ 50) Xiaomi Mi Smart Band 6 fitness tracker. When dismantling, [Raphael] found that the system-on-chip that the show is running on is a Telink TLSR8232. It’s paired with a 160 × 80 display, a small LiPo battery for power, and a vibration motor, as well as a seemingly fake heart rate sensor.

[Raphael] wanted to flash the SOC with a new firmware and learned a lot from the code for a similar part created by [atc1441]. It took me some time to figure out how to program the chip with the somewhat strange SWire interface, however [Raphael] persisted and eventually got things working after a lot of research and experimentation.

From then on there was still more work to be done figuring out how to read capacitive key input and control the screen, however [Raphael] succeeded in the end. The end result was the creation of firmware that would allow him to read Bluetooth Low Energy soil moisture sensors that he installed in his plants at home.

It is not [Raphael], also known [rbaron]’s first bite of the cherry; We’ve already featured his efforts in hacking similar fitness bands! Video after the break.

To draw text, I borrowed the Picopixel bitmap font and wrote a small text rendering function. Everything so that we could enjoy this cinematic masterpiece.

– Raphael (@rbaron_) July 6, 2021

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