请求协助：基于11字节数据识别BLE车轮与曲柄传感器数据

Let's break down your raw hex data step by step, using the BLE Cycling Speed and Cadence (CSC) Measurement characteristic rules. Your sample data is:
0x03 0x6D 0x01 0x00 0x00 0xFC 0x7E 0x2C 0x01 0xF8 0x7E

1. Decode the Flags Byte #

The first byte (0x03) is the flag that tells us what data is included. Converting to 8-bit binary gives 00000011, where each bit has a specific meaning:

• Bit 0 (LSB): 1 → Wheel revolution data is present
• Bit 1: 1 → Crank revolution data is present
• Bits 2-7: 0 → All revolution counts and event times should use 16-bit formatting (though your data length suggests a 32-bit wheel count—we’ll address that quirk below)

2. Parse Wheel Revolution Data #

Your data includes 6 bytes for wheel data (likely a sensor implementation oddity, even though the flag says 16-bit):

• Cumulative Wheel Revolutions: The first 4 bytes (0x6D 0x01 0x00 0x00) are little-endian, so reverse the byte order to get 0x0000016D. Converting to decimal gives 365 total wheel revolutions.
• Last Wheel Event Time: Next 2 bytes (0xFC 0x7E) → little-endian is 0x7EFC. Each unit equals 1/1024 seconds, so calculate the time:

  32508 / 1024 ≈ 31.75 seconds since the last wheel revolution
  

3. Parse Crank Revolution Data #

The final 4 bytes follow the 16-bit format as indicated by the flag:

• Cumulative Crank Revolutions: 2 bytes (0x2C 0x01) → little-endian is 0x012C, which converts to 300 total crank revolutions.
• Last Crank Event Time: 2 bytes (0xF8 0x7E) → little-endian is 0x7EF8. Calculate the time:

  32504 / 1024 ≈ 31.74 seconds since the last crank revolution
  

Quick Note on the Data Length Discrepancy #

Normally, a flag of 0x03 would result in 9 total bytes (1 flag + 2 wheel count + 2 wheel time + 2 crank count + 2 crank time). Your 11-byte data suggests the sensor is sending a 32-bit wheel count despite the flag indicating 16-bit. This is a common edge case with some BLE sensors—you can confirm the correct format by checking if the wheel count increments consistently across multiple samples using the 32-bit value.

内容的提问来源于stack exchange，提问作者Santosh Krishnan