sx8645 Semtech Corporation, sx8645 Datasheet - Page 16

• Manufacturer Part Number: sx8645
• Description: Ultra Low Power, Capacitive Button And Wheel Touch Controller 12 Sensors With Enhanced Led Drivers
• Manufacturer: Semtech Corporation

SX8645
Ultra Low Power, Capacitive Button and Wheel
Touch Controller (12 sensors) with Enhanced LED Drivers
ADVANCED COMMUNICATIONS & SENSING
DATASHEET
The position belonging to the minimum and associated to a sensor is defined arbitrarily. The SX8645 defines the
minimum position to the sensor with the lowest CAP pin index. E.g. if CAP0 is a button (or disabled) and CAP1 to
CAP7 are the sensors of the wheel then the position ‘zero’ starts at CAP1 and the maximum is found at CAP7.
In addition to the wheel position, the SX8645 allows to detect finger rotation. The rotation occurs if the finger
position changes a certain step size between two succeeding scan periods. A very slow moving finger will not be
considered as a rotation as the changing position will be minor. The SX8645 allows detecting a rotate clockwise
(direction min to max) (see Figure 14) and a rotate counter clockwise (direction max to min) (see Figure 15).
rotate clockwise
Wheel rotate clockwise
Figure 14
Wheel rotate counter clockwise
Figure 15
Revision 7_5, February 10
© 2010 Semtech Corp.
www.semtech.com
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