AT42QT2120 Datasheet

26
9634E–AT42–06/12
AT42QT2120
5.15 Address 15: Charge Time
Prolongs the charge-transfer period of signal acquisition by 1 µs per count.
Allows full charge-transfer for keys with heavy Rs / Cx loading.
Range: 0–255
Default: 0
5.16 Address 16 – 27: Detect Threshold (DTHR)
DTHR KEY 0 – DTHR KEY 11: these 8-bit values set the threshold value for each key to
register a detection.
Default: 10 counts
Note: Do not use a setting of 0 as this causes a key to go into detection when its signal is
equal to its reference.
5.17 Addresses 28 – 39: Key Control
GUARD: If set to 1, this key will act as a guard channel. A key set as a guard key does not affect
the Detection Status or Key Status register and the CHANGE
line is not asserted if this key goes
into detect.
AKS: These bits control which keys are included in an AKS group. There can be up to three
groups, each containing any number of keys (up to the maximum allowed for the mode). A
setting of 0 disables AKS for that key.
Each key can have a value between 0 and 3, which assigns it to an AKS group of that number. A
key may only go into detect when it has the largest signal change of any key in its group. A value
of 0 means the key is not in any AKS group.
Table 5-15. Charge Time
Address Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
15 CHARGE TIME
Table 5-16. Detect Threshold
Address Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
16 DTHR KEY 0
::
27 DTHR KEY 11
Table 5-17. Key Control
Address Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
28
Reserved GUARD AKS GPO EN
::
39 Reserved GUARD AKS GPO EN