2.6 QMagic
TM
Proximity Sensor
Key 7 (SNSB7) can be optimized for operation as a hand
proximity sensor via the serial interface (see Section 3.5.2,
Prox = 1). The proximity sensitivity of channel 7 can be
increased by a higher value of Cs. The AKS mode should be
set to mode 101, to ensure that the proximity key does not
lock out other keys or the wheel/slider.
Note that proximity fields are often unstable especially in
products that can move around, such as mobile phones and
MP3 players. In particular, the proximity channel can stick on
after a detection. As soon as possible after proximity
channel 7 becomes active, it should be recalibrated via the
serial interface (see Section 3.5.2, CalK = 1, Cal Key Num
bits = 111) in order to clear the proximity channel .
Design of proximity electrodes requires care, so as to ensure
that the electrode area is maximized whilst ensuring
adequate and easy coupling to a hand as it approaches the
equipment.
2.7 Faulty and Unused Keys
Any sense channel that does not have its sense capacitor
(Cs) fitted is assumed to be either faulty or unused. This
channel takes no further part in operation unless a
host-commanded recalibration operation shows it to have an
in-range burst count again.
This is important for sense channels that have a n open or
short circuit fault across Cs. Such channels would otherwise
cause very long acquire bursts, and in consequence would
slow the operation of the entire QT1106.
Lq
5
QT1106-ISG R8I.05/0906
QUANTUM [ QUANTUM RESEARCH GROUP ]
