Heart rate measuring protocol using Mi Band 1S

I'm trying to implement simple sdk for working with fitness tracker Xiaomi Mi Band. Currently I can track steps, actuate the vibration, handle the sensor touch but I have a problem with heart rate measuring. To measure heart rate, I need to write descriptor to appropriate characteristic to enable handling callback when the value of this characteristic was changed and then write appropriate data to heart rate control point characteristic to directly start the heart rate measure process. The problem is that the heart rate measuring process was not started after the data to initiate this process was successfully written to the characteristic (when the Mi Band starts to measure heart rate then the bottom sensor blinks green). This can be caused by a new firmware of fitness tracker (firmware version: 4.15.12.10; HeartRate version: 1.3.74.64) or there are some defects in my code.

Maybe the protocol is deprecated and there are people who can share me a new protocol. I will be very glad) Thanks.

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