19

SQUAL

Address: 0x05

Access: Read

Reset Value: Undefined

Bit

7

654

3

2

1

0

Field

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 TBD. 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 500 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 21. SQUAL values (white paper)

Mean SQUAL vs Z (white paper)

0

10

20

30

40

50

60

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

Delta from Nominal Focus (mm)

Figure 22. Mean SQUAL vs. Z (white paper)

SQUAL Value (white Paper)

0

10

20

30

40

50

60

70

80

90

100

Count