Silicon Laboratories Si114X User Manual page 9

Name Label
G0 Avg
G1 Thr
G2 iLED1
G3 VIS
G4 IR
G5 PS1
G6 VISst
G7 IRst
G8 PSst
G9 PS1bl
G10 BLVal
G11 BLcnt
G12 BLtst
G13 N/A
G14 N/A
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Table 2. Generic Data Channels—Bottom-Side Ranging Demo
Type
Average of PS1
Detection Threshold
LED Drive Current Level
AutoRanging Ambient Outputs
AutoRanging PS Output
State of Ambient Visible System
State of Ambient IR System
State of PS System
PS Baseline Levels
Baseline Value
Baseline Counter
Baseline Test Value
Unused by PAT
The average of PS1 is more stable and allows for
smaller thresholds for long-range detection.
A detect is triggered when the Avg exceeds the Thr.
The LED driver has a specific LED drive current setting
for it. This value is given in units of mA.
AutoRanging will automatically change the modes of the
photodiodes to avoid saturation. When changing modes,
the raw data output changes levels, but AutoRanging
will scale the raw data so that all measurements are on
the same scale. The output from this channel is the pro-
cessed value which can be used without knowledge of
the photodiode modes.
This channel is the AutoRanging PS output from the
device. This output helps compensate for the affects of
high changes in ambient light levels.
These channels help indicate what mode the sensor is
in during each of their respective measurements. The
four possible modes are as follows: Low Light, High
Sensitivity, High Signal, and Sunlight. These modes are
numbered from zero to three. For more information
about each mode, please consult the data sheet.
AutoRanging uses baselining to determine the no-detect
threshold for readings. Any readings below the values
shown on these channels will be considered no-detect
readings. Any values higher than this baseline will be
shown in the AutoRanging PS Outputs above. For this
Ranging application, this baseline algorithm is bypassed
to allow for the main Ranging algorithm to perform its
own form of baselining.
The Bottom-Side Ranging algorithm has its own baselin-
ing algorithm that baselines on the Avg (G0) channel.
This channel is the current value that the baseline is set
to.
The baselining algorithm picks a rolling maximum value
from Avg (G0) and tests to see if that value can be used
as the new baseline. This is the Baseline Test Value. If
the Avg does not stray too far away from the BLtst value
for 40 samples in a row, this BLtst value will become the
new Baseline Value. The sample counter is on G11 as
the Baseline Counter value.
These channels are reserved for use by the Si1140 Con-
trol Panel.
Rev. 0.1
Si114x-MFB
Description
9