Silicon Laboratories Si114X User Manual page 8

Si114x-MFB
Name Label
G0 Mid 1
G1 Mid 2
G2 Mid 3
G3 MdAvg Midpoint Average
G4 N/A
G5 N/A
G6 iLED1
G7 iLED2
G8 iLED3
G9 VIS
G10 IR
G11 PS1
G12 PS2
G13 PS3
G14 VIS s
G15 IR st
G16 PS st
G17 PS1bl
G18 PS2bl
G19 PS3bl
G20 N/A
G21 N/A
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Table 1. Generic Data Channels—Top-Side Thumb-Scroll Application
Type
Midpoint Timestamps
Unused channels
LED Drive Current Levels
AutoRanging Ambient Outputs
AutoRanging PS Outputs
State of Ambient Visible System
State of Ambient IR System
State of PS System
PS Baseline Levels
Unused by PAT
The firmware records the timestamps for the entry and
exit times of your thumb across each LED. Then a mid-
point is calculated between these points, and the timing
between these midpoints is used to determine gestures.
If all three midpoints are very close to the average of all
three, then a tap gesture is detected.
The unused channels are not in use by software, but
they are available in firmware to use as needed.
Each LED driver has a specific LED drive current setting
for it. These values are 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.
These channels are the AutoRanging PS output from
the device. Raw data measurements are processed by
the AutoRanging firmware to make all the readings
across different modes have the same magnitude. Since
the device switches modes to compensate for ambient
light, the raw data will show jumps when changing
modes. These outputs will not display the jumps
because the firmware is stitching the raw outputs
together.
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 Sensitiv-
ity, High Signal, and Sunlight. These modes are num-
bered 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.
These channels are reserved for use by the Si1140 Con-
trol Panel.
Rev. 0.1
Description