17 address 30: extend pulse time – Rainbow Electronics AT42QT1110-AZ User Manual
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9570H–AT42–02/10
AT42QT1110-MZ/AT42QT1110-AZ
KEY_n_NTHR: the negative threshold for key n (where n is 0–10).
The negative threshold determines how much the signal must fall (compared to the reference)
before a key is considered to be “In Detect”. This level will generally need to be tuned
individually for each key. To disable an individual key, set the threshold for that key to 0.
KEY_n_NHYST: the negative hysteresis applied to key n detection threshold (where n is
0 – 10).
Negative Hysteresis operates as a “modifier” for the negative threshold in order to provide a
greater degree of control over the detection of a “Touch”. When a key signal is first detected as
being under the negative threshold, the threshold is reduced by a factor corresponding to the
selected negative hysteresis. This means that the key will not go in and out of detection when
the signal is on the borderline between drift-compensation or touch detection.
The settings for negative hysteresis are:
00
No change to negative threshold
01
12.5% reduction in negative threshold
10
25% reduction in negative threshold
11
37.5% reduction in negative threshold
Default KEY_n_NTHR value:
10 counts
Default KEY_n_NHYST value:
2 (25 percent)
7.17
Address 30: Extend Pulse Time
HIGH_TIME: Number of µs to extend the high pulse time.
LOW_TIME: Number of µs to extend the low pulse time.
25
KEY_6_NTHR
KEY_6_NHSYT
26
KEY_7_NTHR
KEY_7_NHSYT
27
KEY_8_NTHR
KEY_8_NHSYT
28
KEY_9_NTHR
KEY_9_NHSYT
29
KEY_10_NTHR
KEY_10_NHSYT
Table 7-16.
Negative Threshold/Negative Hysteresis (Continued)
Address
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Table 7-17.
Extend Pulse Time
Address
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
30
HIGH_TIME
LOW_TIME