Data format for anyone interested

[hyx0329]

On my device, raw data(captured with nRF Connect): 0x10FFC00A07C71388000025E9CAE7DF23150609596F646131

Parsed:

• 0x10 0xFF, length 16, Manufacturer Specific Data(see specification)
  • 0xC0: presumably feature bits, see WSP(Weight Scale Profile)
  • 0x0A: count(here 10), how many measurements taken, may also taken as a sequential packet ID, reset to 0 when battery reinstalled
  • 0x07C7: body weight, here 19.91, unit later
  • 0x1388: presumably body impedance, here is a fake one(which is a constant value)
  • 0x0000: ?
  • 0x25: flag bits, later
  • E9CAE7DF2315: bluetooth MAC address(should be the same with the hardware's)
• 0x06 0x09, length 6, Complete Local Name(see specification)
  • 0x596F646131: Yoda1

The manufacture bytes are repurposed(the first 2 bytes, 0xC00A in the example above), they are not random values.

Flag bits indicate the packet type and body weight unit, examples:

- 0x24: 0b0000000000100100, not stable(bit 0 equals 0), unit 斤(jin, =1/2 kilogram, aka. catty)
- 0x29: 0b0000000000101001, stable(bit 0 equals 1), unit kilogram

So, for the raw data example above, the body weight is 19.91斤 which is approximately 10Kg

bit 0: stable(1) or not(0)
bit 2: unit Kg(1) or not(0)
bit 3: one decimal(1) or two(0)
bit 5: unknown

Edit: I found I made some mistakes in the past when implementing this scale in OpenScale, updated.

[denysvitali]

Thanks for sharing!