8.1.10.3 Overcoming Case Twisting (Anti-Twist)
The anti-twist algorithm reduces the likelihood of false detection when the case is twisted, which could cause
unintended mechanical activation of the buttons, or an opposite reaction in two adjacent buttons. When this
algorithm is enabled, detection of button presses is suppressed if any button’s output data is negative by a
configurable threshold. The anti-twist algorithm can be enabled by configuring
Register TWIST (Address 0x19)
.
Time
DATA
Threshold = 128+Hysteresis
Button 0
Button 1
Twisting effect of
Buttons 0 and 1.
Intentional Press of
Button 1.
OUTPUT
without
Anti-twist
(High = Button
Press Detected)
Button 0
Button 1
OUTPUT
with
Anti-twist
(High = Button
Press Detected)
Button 0
Button 1
Time
Time
Figure 8-12. Illustration of the Anti-Twist Feature
8.1.10.4 Mitigating Metal Deformation (Anti-Deform)
This function filters changes due to metal deformation in the vicinity of one or more buttons. Such metal
deformation can be accidentally caused by pressing a neighboring button that does not have sufficient
mechanical isolation. The user can specify which buttons to join the anti-deform group by configuring
Register
COMMON_DEFORM (Address 0x1A)
.
8.1.11 Reporting Interrupts for Button Presses, Raw Data Ready and Error Conditions
INTB, the LDC3114 interrupt pin, is asserted when a button press or an error condition occurs. The default
polarity is active low and can be configured through
Register INTPOL (Address 0x11)
.
shows the LDC3114 response to a single button press on Channel 0. At the end of the button
sampling window following a press of Button 0, the OUT0 pin and INTB pin are asserted. The OUT_STATUS bit
changes from 0 to 1, and remains so until a read of the STATUS register clears it. The OUT
n
(
n
= 0, 1, 2, or 3)
and INTB pins are asserted until the end of the button sampling window following the release of the button.
SNOSDD0 – DECEMBER 2021
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