at42qt2100 ATMEL Corporation, at42qt2100 Datasheet - Page 6

• Manufacturer Part Number: at42qt2100
• Description: Qtouch Touch Sensor Ic
• Manufacturer: ATMEL Corporation

2.3
2.4
2.5
2.6
6
User Interface Layout and Options
Slider and Wheel Construction
Proximity Effect
SPI Interface
AT42QT2100
The QT2100 can sense through all common plastics or glass or other dielectric materials up to
10 mm thick. It can be used to implement a linear slider or rotary scroll wheel plus seven
additional discrete keys. The slider or wheel indicates absolute positions.
The QT2100 can be connected to a linear slider element (see
wheel. Selection of linear operation or wheel is set through an SPI command.
Any number of keys can be programmed to have hand or body proximity. By using a relatively
large electrode inside the product’s enclosure and a larger value of CsB, the product can auto
power up or activate its display with hand approach. This simple feature can add enormous
sales appeal to almost any product.However, if using AKS see
The QT2100 is an SPI slave mode device, utilizing a four-wire full-duplex SPI interface.
In addition to the standard four SPI signals (SS, SCK, MOSI and MISO), there is a DRDY
(data ready) output which may optionally be used to time communications such that they do
not occur during channel measurement bursts. During each burst DRDY is held low by the
QT2100. After each group burst, DRDY is driven high for 500 µs or until 3 bytes have been
exchanged.
The QT2100 also provides a CHANGE signal to indicate when there has been a change in
detection state. This removes the need for the host to poll the QT2100 continuously.
On each SPI transfer the host sends three bytes to the QT2100 and the QT2100
simultaneously sends three bytes to the host. The bytes sent from the host provide the
QT2100 with all its configuration information; the bytes sent from the QT2100 convey the
states of the touch keys and slider or wheel.
Section 4.3.6 on page
Section 3.5 on page
9554CX–AT42–11/11
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