20

Figure 10. Mean squal vs. Z (White Paper)

SQUAL

Address: 0x05

Squal Quality Register

Access: Read

Reset Value: 0x00

Bit

76543210

Field

SQ7

SQ6

SQ5

SQ4

SQ3

SQ2

SQ1

SQ0

Data Type: Upper 8 bits of a 9-bit unsigned integer.

USAGE: SQUAL (Surface Quality) is a measure of the number of valid features visible by the sensor in the current

frame.

The maximum SQUAL register value is 180. Since small changes in the current frame can result in changes in

SQUAL, variations in SQUAL when looking at a surface are expected. The graph below shows 250 sequentially

acquired SQUAL values, while a sensor was moved slowly over white paper. SQUAL is nearly equal to zero,

if there is no surface below the sensor. SQUAL is typically maximized when the navigation surface is at the

optimum distance from the imaging lens (the nominal Z-height).

Figure 9. Squal values (white paper)

0

10

20

30

40

50

60

1

55

109

163 217 271 325 379 433 487 541 595

649 703 757 811 865

Count

Squal

Mean SQUAL vs Z

-10

0

10

20

30

40

50

60

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

Delta from Nominal Focus (mm)

Avg-3sigma

Avg

Avg+3sigma

All rights strictly reserved any portion in this paper shall not be reproduced, copied or transformed to any other forms without permission.

PixArt Imaging Inc.

PixArt Imaging Inc.

ADNS-3000 Low Power Optical Mouse Sensor