Data Logging
11
11.1.5. Approximate Download Time Calculation.
• The data will be downloaded at a baud-rate of 115200 bps, at 8N1
• Communication time per Byte is (9 bits), = 78.125uS
• Communication time per Block is (256+8 = 264Bytes) = 20625 uS = 20.625 mS
• Communication time per 500 blocks is = 10312.5 mS = 10.3125 Sec
• Estimated processing time at the Smartphone end and in the UWBT device
is approximately 150% of the time taken for data communication
• Approximate data download time = 10.3125+15.46875= 25.78125 sec
11.1.6. Circular Buffer
• Circular buffer has 500 blocks of data.
• If internal log memory is not erased, then “download request” from USP
/PC application, will always downloads/receives 500 blocks of UWBT
logged data.
• Else the UWBT device replies “Device Memory Empty” acknowledgement.
• The USP / PC application will decode UWBT logged data and then splits
into files, in accordance with log sessions.
11.1.6.1. Circular Buffer Off – Single Session
• The session starts at point A (100th block), and ends at point B (500th block).
• While downloading, the USP receives, 1st Block (oldest data) first and 500th
Block (newest data) at the end. The receiving block order should be (1 to
500).
• Since circular buffer is off, the log will end at Point B, and “End of Memory”
indication will be shown at Point B.
Figure 11-2: Circular Buffer Off – Single Session
100 101 ….
1
….
….
….
2
499 500
START
A
END
B
100 101
….
1
….
….
….
2
499 500
START
1
A
END
1
B
…. …. 340 341
START
2
C
END
2
D
100 101
….
1
….
….
….
2
499 500
…. …. 340 341
START
A
END
B
100 101
….
1
….
….
….
2
499 500
…. …. 141 142
START
A
END
B
100 101
….
50
….
….
….
51
499 500
START
1
A
END
1
B
…. …. 340 341
START
2
C
END
2
D
1
….
….
2
100 101
….
1
….
….
….
2
340 341
…. …. 200 201
START
1
A
END
2
D
…. …. 499 500
END
1
B
START
2
C
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