PixArt Imaging Inc.
PAS005B
CMOS Image Sensor IC
concurrently. The shutter closing edge must be earlier than the Vsync edge by programming proper register
value LPF (Line-per-Frame). The suggested setting of ny (ne) in this mode is 0 to guarantee simultaneous
exposure in the shutter opening period. However, different setting is accptable depend on application.
Snapshot mode 2: register seq_exp=0
When the exposure time is less than the mechanical shutter speed limitation, snapshot mode 2 is chosen. The
exposure period is now controlled by exposure start point and shutter closing edge as shown in Fig. 5. The
exposure starting point is setted by register ny and ne, and the sensor array will be started to exposure
simultaneously. Again, the shutter closing edge must be earlier than the Vsync edge.
All these two snapshot modes can be external triggered by pin “Sync” as shown in Fig. 4.4-1 and 4.4-2.
Mechanical shutter
opening period
Mechanical
shutter
ny=0, ne=0
start point
end point
Active Exposure time
Array
leakage
Image exposure and
readout timing
Array
leakage
Vsync extension
programmed by LPF
Non-Valid
Data
Valid
Data
Vsync
External Sync
Fig. 4.4-1 Snapshot mode one – Exposure time controlled by shutter.
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