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AT42QT1110-MU

11-key QTouch® Touch Sensor IC

Atmel Corporation 

4.5 CHANGE Pin

The CHANGE pin can be configured using the Comms Options setup byte (see Section 7.5 on page 30) to act in one

of two modes:

 Data mode

 The CHANGE pin is asserted (pulled low) when the detection status of a key changes from that last

sent to the host; that is when a key-touch or key-release event occurs.

 The CHANGE pin is pulled low when a key status changes and is only released when the “Send All

keys” report is requested (0xC1), or the key status information bytes are read in Quick SPI mode (see

Section 7.5 on page 30).

 Touch mode

 The CHANGE pin is pulled low when one or more keys are in detect. The CHANGE pin remains low as

long as there is a key in detect, regardless of communications.

 The CHANGE pin is released when there are no keys in detect. No host communications are required to

release the CHANGE pin.

4.6 Stand-alone Mode

The QT1110 can operate in a stand-alone mode without the use of the SPI interface. The settings are loaded from

EEPROM and the device operates in 7-key mode using the Detect outputs.

4.7 Key Modes

4.7.1

11-key Mode

In 11-key mode, the device can sense up to 11 keys. Alternatively, one key can be replaced by the SYNC line as an

external trigger input (see Section 4.8.2 on page 19).

11-key mode is configured by setting the MODE bit in the Device Mode setup byte (see Section 7.4 on page 29).

Key acquisition can be triggered in one of two ways: using the internal clock to trigger acquisition either at a fixed

repetition period or in a continuous “free run” mode (see Section 4.8.1), or using the SYNC pin to provide an external

trigger (see Section 4.8.2 on page 19),

4.7.2

7-key Mode

In 7-key mode, the detect outputs DETECT0 to DETECT6 become active on pins 22 – 27 and 30. These outputs

provide configurable PWM signals that indicate when each of the keys is touched.

7-key mode is configured by clearing the MODE bit in the Device Mode setup byte (see Section 7.4 on page 29).

Each DETECT output can be individually configured to output a PWM signal while the matching key is in detect or

out of detect. This signal can be one of nine levels, ranging from low (PWM = 0%) to high (PWM = 100%). This

allows for the use of an indicating LED. This is achieved by enabling the appropriate bit in the Key to LED setup byte

(see Section 7.14 on page 35), and setting the desired outputs levels or PWMs in setup addresses 9 to 15 (see

Section 7.12 on page 33).

AT42QT1110-MU / AT42QT1110-AU [DATASHEET] 18

9520J–AT42–05/2013

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