ADNS-4000 Avago Technologies US Inc., ADNS-4000 Datasheet - Page 20

• Manufacturer Part Number: ADNS-4000
• Description: SENSOR OPTICAL MOUSE LP 8DIP
• Manufacturer: Avago Technologies US Inc.

Specifications of ADNS-4000

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

SQUAL
Squal Quality Register
Access: Read
Data Type:
USAGE:
20
Field SQ7
Bit 7
Address: 0x05
Reset Value: 0x00
Upper 8 bits of a 9-bit unsigned integer.
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 128. 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 800 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 20. Squal values (white paper)
Figure 21. Mean squal vs. Z (White Paper)
60
50
40
30
20
10
60
50
40
30
20
10
0
0
6
SQ6
1.6
1.8
5
SQ5
Distance from Lens Reference Plane to Tracking Surface - Z (mm)
2
4
SQ4
2.2
2.4
Count
3
SQ3
2.6
2
SQ2
2.8
3
1
SQ1
3.2
Avg-3sigma
Avg
Avg+3sigma
3.4
0
SQ0