31

Figure 28. Mean shutter vs. Z (white paper)

The maximum value of the shutter is dependent upon the setting in the Shutter_Max_Bound_Upper and Shutter_

Max_Bound_Lower registers.

Shutter_Lower

Address: 0x0e

Access: Read

Reset Value: 0x85

Shutter_Upper

Address: 0x0f

Access: Read

Reset Value: 0x00

Data Type: Sixteen bit unsigned integer.

USAGE: Units are clock cycles. Read Shutter_Upper first, then Shutter_Lower. They should be read consecutively. The

shutter is adjusted to keep the average and maximum pixel values within normal operating ranges. The shutter value

is checked and automatically adjusted to a new value if needed on every frame when operating in default mode.

When the shutter adjusts, it changes by ± 1/16 of the current value. The shutter value can be set manually by setting

the AGC mode to Disable using the Extended_Config register and writing to the Shutter_Maximum_Bound registers.

Because the automatic frame rate feature is related to shutter value. It may also be appropriate to enable the Fixed

Frame Rate mode using the Extended_Config register.

Shown below is a graph of 250 sequentially acquired shutter values, while the sensor was moved slowly over white

paper.

Bit

7

6

5

4

3

2

1

0

Field

Shutter_Lower

Address: 0x0e

Access: Read

Reset Value: 0x85

Bit

7

6

5

4

3

2

1

0

Field

Mean Shutter vs Z (White Paper)

Distance from Nominal Focus (mm)

0

20

40

60

80

100

120

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

Avg

Avg - 3sigma

Avg + 3sigma

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PixArt Imaging Inc.

PixArt Imaging Inc.