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Adjust measurement result for influence of optical window.
BH1715FVC is including in adjust measurement result function for influence of optical window. Adjust is done by changing
measurement time. For example, if transmission rate by optical window is 1 / N, then adjust is done by measurement time is
set to "initial value * N".
Measurement time register ( Mtreg ) is 8bit register. Initial value is "0100_0101" ( 45xh ). Please change this register value
via to I
2
C Bus interface.
ex ) Case of transmission rate is 50%.
Please change Mtreg value from "0100_0101" to "1000_1010".
1)
Changing High bit of Mtreg
ST
Slave Address
R/W
0
Ack
01000_100 Ack
SP
2)
Changing Low bit of Mtreg
ST
Slave Address
R/W
0
Ack
011_01010 Ack
SP
3)
Input Measurement Command.
ST
Slave Address
R/W
0
Ack
0001_0000 Ack
SP
※
This example is High Resolution mode, but it accepts the other measurement.
4)
After about 240ms, measurement result is registered to Data Register. ( High Resolution mode is typically 120ms, but
measurement time is set twice. )
Supported Mtreg value is seeing below.
Min. Typ.
Max
Supported value ( hex )
0010_1101
( transmission rate 153% )
0100_0101
( transmission rate 100% )
1111_1110
( transmission rate 27.2% )
For example BH1715FVC is possible to detect min. 0.33 lx when Mtreg value is “1111_1110” at H-Resolution mode.
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