AT42QT2120 Datasheet

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9634E–AT42–06/12
AT42QT2120
5.11 Address 11: Detection Integrator (DI)
DI: Allows the DI level to be set for each key. This 8-bit value controls the number of consecutive
measurements that must be confirmed as having passed the key threshold before that key is
registered as being in detect. The minimum value for the DI filter is 1. A settings of 0 for the DI
also defaults to 1.
Default: 4 (maximum = 32)
5.12 Address 12: Touch Recal Delay (TRD)
If an object unintentionally contacts a key resulting in a detection for a prolonged interval it is
usually desirable to recalibrate the key in order to restore its function, perhaps after a time delay
of some seconds.
The Touch Recal Delay timer monitors such detections; if a detection event exceeds the timer's
setting, the key will be automatically recalibrated. After a recalibration has taken place, the
affected key will once again function normally even if it is still being contacted by the foreign
object. This feature is set globally.
TRD can be disabled by setting it to zero (infinite timeout) in which case the key will never
autorecalibrate during a continuous detection (but the host could still command it).
TRD is set globally, which can range in value from 1 – 255. TRD above 0 is expressed in 0.16 s
increments.
Default: 255 (Comms) 255 (Standalone)
5.13 Address 13: Drift Hold Time (DHT)
This is used to restrict drift on all keys while one or more keys are activated. DHT defines the
length of time the drift is halted after a key detection. When DHT = 0, drifting is never
suspended, even during a valid touch of another key.
Table 5-11. Detection Integrator
Address Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
11 DI
Table 5-12. Touch Recal Delay
Address Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
12 TRD
Table 5-13. Drift Hold Time
Address Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
13 DHT