Data 143 (Crash Sensor Data)¶
Packets the acceleration data when the crash event is detected.
Note
This data is only used for Record 75H. If another record carries this data, its ‘Data Length’ will always be 0.
The frame format of the Data 143 unit is as follows:
For example (Total 310 bytes):
80 8F 81 32 00 00 33 FF 01 2C 00 02 00 B7 08 5E 00 04 00 02 00 02 FF F5 00 B9 08 60 00 02 00 00 00 00 FF FD 00 C4 08 65 00 04 00 00 00 00 FF FA 00 B3 08 69 00 03 00 02 00 00 FF F6 00 B3 08 63 00 04 00 03 00 00 00 00 00 C3 08 4E 00 02 00 04 00 00 00 07 00 BE 08 55 00 04 00 02 00 01 00 02 00 BC 08 61 00 05 00 00 00 02 00 03 00 BE 08 60 00 03 FF FE 00 01 FF FE 00 BB 08 60 00 04 00 01 00 00 FF F4 00 BD 08 5B 00 01 FF FF 00 00 FF F3 00 B6 08 5E 00 02 00 00 00 00 FF F2 00 B6 08 56 00 01 00 01 00 00 FF F9 00 C1 08 66 00 01 00 00 00 01 00 00 00 C1 08 5E 00 02 00 03 00 00 FF F9 00 C0 08 5F 00 04 00 01 00 01 00 05 00 C3 08 61 00 00 00 00 00 00 00 06 00 B9 08 60 00 05 00 01 00 00 FF FA 00 BF 08 68 00 02 FF FF FF FF FF F7 00 BA 08 66 00 04 00 01 FF FE FF FF 00 BE 08 5E 00 02 00 00 00 00 FF FC 00 BE 08 66 00 03 00 01 00 02 FF F7 00 B8 08 5E 00 00 00 04 00 03 FF FE 00 C5 08 5E FF FE 00 04 00 02 00 03 00 BE 08 60 FF FF 00 03 00 02
Parts |
Fields |
Length (Byte) |
Range/Format |
Default |
|---|---|---|---|---|
ID |
Data ID |
2 |
808FH (143) |
808FH (143) |
Length |
Data Length |
1 or 2 |
00H-7FH or 8080H-84B6H |
|
Content |
Crash ID |
1 |
00H-FFH |
|
Data Type |
1 |
|||
Acceleration Parameter |
1 |
|||
Reserved |
1 |
00H-FFH |
FFH |
|
Length |
2 |
0000H-04B0H |
||
Data |
N |
Crash ID
When the terminal detects a crash event, it will automatically assign a crash ID.
The ID is convenient to distinguish multiple adjacent crash events. It rolls from 00H to FFH.
Data Type
The highest bit (bit7) represents the type of data recorded, the upper 3 bits (bit 6 to bit 4) are reserved, the next 3 bits (bit3 to bit1) represent the data sampling frequency, and the lowest bit (bit0) indicates the time of the data.
Details are as follows:
Type (Bit7)
0b0 - Acceleration data.
Reserved (Bit6 to Bit4)
Reserved bits, set to 0b000 by default.
Sensor Frequency (Bit3 to Bit1)
Indicates the sampling frequency of sensor data.
0b000 - 100Hz.
0b001 - 200Hz.
Others - Reserved.
Time Point (Bit0)
0b0 - The data is recorded before crash.
0b1 - The data is recorded after crash.
Acceleration Parameter
The upper 4 bits represent the acceleration range, and the lower 4 bits represent the acceleration resolution. In particular, FFH means the terminal cannot obtain this information.
Range (Bit7 to Bit4)
0b0000 - ±2g.
0b0001 - ±4g.
0b0010 - ±8g.
0b0011 - ±16g.
Others - Reserved.
Resolution (Bit3 to Bit0)
0b0000 - 0.98 mg/LSB.
0b0001 - 1.95 mg/LSB.
0b0010 - 3.91 mg/LSB.
0b0011 - 7.81 mg/LSB.
0b0100 - 0.06 mg/LSB.
0b0101 - 0.12 mg/LSB.
0b0110 - 0.24 mg/LSB.
0b0111 - 0.49 mg/LSB.
Others - Reserved.
Length
Indicates the total number of bytes in the ‘Data’ field.
If the value is 0, the ‘Data’ field is absent.
Data
This field consists of one or more sets of sensor raw data.
If the highest bit of ‘Data Type’ is 0, then each set of sensor data is 3-axis data, if the highest bit of ‘Data Type’ is 1, then each set of sensor data is 6-axis data.
For acceleration data, each data is a 16-bit signed integer (2 bytes). The acceleration resolution can be known from the ‘Acceleration Parameter’. For example, if the resolution is 0.49 mg/LSB and the 16-bit signed integer is 0123H (i.e. 291), then the corresponding acceleration can be calculated to be 142.59 mg (291*0.49=142.59).
The definition of a set of 3-axis data is as follow:
A Set of 3-axis Data
Length: 6 bytes
The 6 bytes represent 3-axis (X/Y/Z) acceleration data. The order is as follows:
X-axis Acceleration - 2 bytes. It is a 16-bit signed integer.
Y-axis Acceleration - 2 bytes. It is a 16-bit signed integer.
Z-axis Acceleration - 2 bytes. It is a 16-bit signed integer.
For example, 0123F1003012H means that X-axis acceleration data is 291 (0123H), Y-axis acceleration data is -3840 (F100H) and Z-axis acceleration data is 12306 (3012H).