ADNS-2120 Avago Technologies US Inc., ADNS-2120 Datasheet - Page 25

• Manufacturer Part Number: ADNS-2120
• Description: SOLID STATE OPTICAL MOUSE SENSOR
• Manufacturer: Avago Technologies US Inc.

Specifications of ADNS-2120

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: Q2072083D

SQUAL
Access: Read
Data Type: Upper 8 bits of a 10-bit unsigned integer.
USAGE: SQUAL (Surface Quality) is a measure of ¼ of the number of valid* features visible by the sensor in the current
frame. Use the following formula to find the total number of valid features.
Number of features = SQUAL register value *4
The maximum SQUAL register value is 169. 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 26. Squal values (white paper)
Figure 27. Mean squal vs. Z (white paper)
25
Field
90
80
70
60
50
40
30
20
10
Bit
85
80
75
70
65
60
0
0
-1.0
25
SQ
7
-0.8
7
50
-0.6
Squal Values (White Paper)
SQ
6
Delta from Nominal Focus (mm)
6
75
Mean SQUAL vs Z (White Paper)
-0.4
100
-0.2
SQ
5
Address: 0x05
Reset Value: 0x00
5
125
0.0
SQ
150
0.2
4
4
0.4
175
SQ
3
0.6
3
200
0.8
225
SQ
2
2
1.0
250
SQ
1
1
Avg
Avg - 3sigma
Avg + 3sigma
SQ
0
0