7

AT42QT1060 [DATASHEET]

9505H–AT42–04/2015

2.4.3

PWM Mask

A 1 in any bit position in this mask sets the corresponding pin to operate in PWM mode when its user output buffer is

active and configured as an output. A zero sets the pin in digital mode. The PWM value is set in the PWM register

that is writable via I2C communication.

2.4.4

Detection Mask

A 1 in any bit position in this mask sets the corresponding pin to be controlled by the status register. If the pin is

configured as an output, it is asserted automatically if there is a detection on the corresponding sensor channel. A

zero in any bit sets the pin to be controlled by the user output buffer, allowing the user to control the pins directly.

2.4.5

Active Level Mask

A 1 in any bit position in this mask sets the corresponding pin to be active high if configured as an output. A zero sets

the pin to be active low.

2.5

Acquisition/Low Power Modes (LP)

There are several different acquisition modes. These are controlled via the Low Power (LP) mode byte (see Section

5.12 on page 20) which can be written to via I2C communication.

LP mode controls the intervals between acquisition measurements. Longer intervals consume lower power but have

increased response time. During calibration and during the detect integrator (DI) period, the LP mode is temporarily

set to LP mode 1 for a faster response.

The QT1060 operation is based on a fixed cycle time of approximately 16 ms. The LP mode setting indicates how

many of these periods exist per measurement cycle. For example, if LP mode = 1, there is an acquisition every cycle

(16 ms). If LP mode = 3, there is an acquisition every 3 cycles (48 ms), and so on.

SLEEP mode (LP mode = 0) is available for minimum current drain. In this mode, the device is inactive, with the

device status being held as it was before going to sleep, and no measurements are carried out.

LP settings above mode 32 (512 ms) result in slower thermal drift compensation and should be avoided in

applications where fast thermal transients occur.

If LP mode = 255 the device operates in Free-run mode. In this mode the device will not enter LP mode between

measurements. The device continuously performs measurements one after another, resulting in the fastest

response time but the highest power consumption.

2.6

Adjacent Key Suppression (AKS) Technology

The device includes the Atmel-patented Adjacent Key Suppression technology, to allow the use of tightly spaced

keys on a keypad with no loss of selectability by the user.

There can be one AKS group, implemented so that only one key in the group may be reported as being touched at

any one time. A key with a higher delta signal dominates and pushes a key with a smaller delta out of detect. This

allows a user to slide a finger across multiple keys with only the dominant key reporting touch.

The keys which are members of the AKS group can be set via the AKS mask (see Section 5.15 on page 21). Keys

outside the group may be in detect simultaneously.

For maximum flexibility there is no automatic key recalibration timeout on key detection. The user should issue a

recalibration command if the key has been in detect for too long, for example for more than 30 seconds (see Figure

2.10).