SX8635I05AWLTRT SEMTECH [Semtech Corporation], SX8635I05AWLTRT Datasheet - Page 52

• Manufacturer Part Number: SX8635I05AWLTRT
• Description: Low Power, Capacitive Button and Wheel Touch Controller with Enhanced LED
• Manufacturer: SEMTECH [Semtech Corporation]

ADVANCED COMMUNICATIONS & SENSING
A reliable wheel operation requires a coherent setting of the registers.
The pressure represents the finger touch on the sensors of the wheel and it used to determine if a wheel is
touched or released.
In case the pressure equals zero the wheel status is released.
In case the pressure is larger as the Wheel
Figure 51 shows an example of a touch and a release. The ticks will vary slightly around the zero idle state.
When the touch occurs the ticks will rise sharply. At the release of the wheel the ticks will go down rapidly and
converge to the idle zero value.
Revision 7_8, October 10
Wheel Parameters
Address
0x31
- N is the number of sensors,
- A sensor with ticks smaller than the CapThreshold is not taken into account for calculating the pressure
Name
WhlOffset
WhlPressur
0
Bits
7:0
Figure 51 T
e
(12 sensors) with Enhanced LED Drivers and Proximity Sensing
Description
…
0x64: 100%
A succeeding position difference, at the scan period, above the threshold is
considered as a rotate clockwise or counter clockwise.
Defines the angle (offset /256 * 360 degree) added to the wheel position in
clockwise direction.
0x00: 0 (default)
0x01: 1/256
…
0xFF: 255/256
= no-touch
= touch
= scan events @ scan period
=
Table 19
© 2010 Semtech Corp.
Hysteresis
Low Power, Capacitive Button and Wheel Touch Controller
CapThreshold
∑
N
i
ouch and Release Example
WhlHysteresis
WhlHysteresis
=
−
0
1
Wheel Parameters
(
ticks
(touch debounce = 1)
(touch debounce = 1)
the wheel status is touched.
52
Touch
Touch
_
diff
) (
i
time
−
(release debounce = 0)
(release debounce = 0)
CapThresh
Release
(
i
))
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SX8635