PixArt Imaging Inc.

PAS005B

CMOS Image Sensor IC

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PixArt Imaging Inc.

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

Non-Valid

Data

Vsync

Active Exposure time

start point

end point

Valid

Data

Array

leakage

Array

leakage

Mechanical

shutter

ny=0, ne=0

Image exposure and

readout timing

Vsync extension

programmed by LPF

External Sync

Fig. 4.4-1 Snapshot mode one – Exposure time controlled by shutter.