Amazon link: (https://www.amazon.com/dp/B07FKCGDCH/)
Description: This is a bluetooth enabled home body scale with BMI and body fat analysis. The scale has four electrodes that measure impedance. This value is included in the measurment reported via the bluetooth stack. Once the scale is on it is shown on a Bluetooth scan as Health Scale. I have noticed that Bluetooth remains available, only shortly, even after the display turns off. This is not always the case.
It is possible to read and write to the device (I have not tested writing to it).
Read/Notify (UUID): 0xFFF4
Write (UUID): 0xFFF1
Struct (can be copied into 010 Editor) (11 bytes total) (ushort=2 bytes):
struct zoetouch_scale {
byte scale_reading_type_identifier;
ushort unknown;
ushort weight;
ushort unknown2;
ushort impedence;
ushort unknown3;
};I have verifiied values for scale_reading_type_identifier and weight.
Example of weight extraction and calculation :
CF0000B801000000000076
actual_weight = weight_int * 0.01
B801 turns into 440 unsiged integer which will give us 4.4 kg
When providing a scale measurement scale_reading_type_identifier has the value of CF
If I am not mistaken, it looks like the Android app uses the impedance for calculating the BMI only. Everything else is just formulas using data you input into the app (i.e., height, age etc.).
Default message broadcast when on and nothing is placed on the scale:
CF000000000000000001CE
EOF