ADNS-5020 Avago Technologies US Inc., ADNS-5020 Datasheet - Page 18

• Manufacturer Part Number: ADNS-5020
• Description: Optoelectronic Miscellaneous, Other
• Manufacturer: Avago Technologies US Inc.

Specifications of ADNS-5020

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

SQUAL
Access: Read
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.
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The maximum SQUAL register value is 144. 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 13. Squal values (white paper).
Figure 14. Mean squal vs. Z (white paper).
100
-10
70
60
50
40
30
20
10
90
80
70
60
50
40
30
20
10
0
0
1
1.6
Bit
Field
101
1.8
Delta from Nominal Focus (mm)
201
2
Mean Squal vs Z (White paper)
7
SQ
Address: 0x05
Reset Value: 0x00
7
2.2
Squal (White paper)
301
2.4
401
6
SQ
2.6
Count
6
501
2.8
3
5
SQ
601
5
3.2
701
4
SQ
Avg-3sigma
Avg
Avg+3sigma
801
4
3
SQ
3
2
SQ
2
1
SQ
1
0
SQ
0