PixArt Imaging Inc.
ADNS-3090 High-Performance Optical Mouse Sensor
SQUAL
Address: 0x05
Access: Read
Reset Value: 0x00
Bit
7
6
5
4
3
2
1
0
Field
SQ
SQ
SQ
SQ
SQ
SQ
SQ
SQ
0
7
6
5
4
3
2
1
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).
SQUAL Values (White Paper)
Z =2.4mm, Circle@7.5" diameter, Speed = 6ips
100
90
80
70
60
50
40
30
20
10
0
1
101
201
301
401
501
601
701
Counts
Figure 26. Squal values (white paper)
SQUAL vs Z (White Paper)
Resolution = 3500cpi, Circle@7.5" diameter, Speed = 6ips
100
90
80
70
60
50
40
30
20
10
0
Avg-3sigma
Avg
Avg+3sigma
1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4
Distance from Lens Reference Plane to Navigation Surface, Z (mm)
Figure 27. Mean squal vs. Z (white paper)
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.
E-mail: fae_service@pixart.com.tw
26
PIXART [ PIXART IMAGING INC. ]
