ADNS-2620 Avago Technologies US Inc., ADNS-2620 Datasheet - Page 21

• Manufacturer Part Number: ADNS-2620
• Description: Optical Mouse Sensor,DIP
• Manufacturer: Avago Technologies US Inc.

Specifications of ADNS-2620

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: 516-2238-5; ADNS-2620; Q2073278A

SQUAL
Access: Read
Data Type: Upper 8 bits of a 9-bit integer.
USAGE:
1
SQUAL (Surface QUALity) is a measure of the number of features visible by the sensor in the current frame.
Number of Features = SQUAL Register Value x .
The maximum value is . 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 0 sequentially acquired SQUAL values, while a sensor was moved slowly over white paper. SQUAL is nearly equal to zero when there is no
surface below the sensor.
Field
Bit
SQ
7
7
Figure 32. Typical Mean SQUAL vs. z
(white paper).
1.50
1.25
1.00
0.75
0.50
0.25
0
-1.0
DELTA FROM NOMINAL FOCUS (mm)
-0.6
SQ


-0.2
Address: 0x44
Reset Value: 0x00
0.2
SQ

0.6

X
X
X
+
–
3
3
σ
σ
1.0
SQ


The focus point is important and could affect the SQUAL
value. Figure 32 shows another setup with various z-
heights. This graph clearly shows that the SQUAL value is
dependent on focus distance.
Note: The data is obtained by getting multiple readings
over different heights.
SQ


SQ


SQ
1
1
SQ
0
0