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2.6 QMagic

TM

Proximity Sensor 2.7 Faulty and Unused Keys

Key 7 (SNSB7) can be optimized for operation as a handproximity 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 inproducts 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 proximitychannel 7 becomes active, it should be recalibrated via theserial 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 ensurethat the electrode area is maximized whilst ensuring adequate and easy coupling to a hand as it approaches the equipment. 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 anin-range burst count again.This is important for sense channels that have an open orshort circuit fault acrossCs. Such channels would otherwisecause very long acquire bursts, and in consequence wouldslow the operation of the entire QT1106. 5QT1106_8 I R0.07_0907