ATAVRQTOUCHX Atmel, ATAVRQTOUCHX Datasheet - Page 15

• Manufacturer Part Number: ATAVRQTOUCHX
• Description: BOARD EVAL CAPACITIVE TOUCH
• Manufacturer: Atmel
• Series: QTouch™r

Specifications of ATAVRQTOUCHX

• Sensor Type: Touch, Capacitive
• Sensing Range: 1 Slider, 1 Wheel, 2 Buttons
• Interface: USB
• Voltage - Supply: 5V, USB
• Embedded: Yes, MCU, 8-Bit
• Utilized Ic / Part: AT90USB1287, ATxmega128A1
• Silicon Manufacturer: Atmel
• Silicon Family Name: ATxmega
• Kit Contents: Board
• Svhc: No SVHC (15-Dec-2010)
• Core Architecture: AVR
• Core Sub-architecture: AVR19
• Kit Features: One Slider, One Wheel And 2
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Sensitivity: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

QMatrix uses a pair of sensing electrodes for each channel. One is an emitting electrode into
which a charge consisting of logic pulses is driven in burst mode. The other is a receive electrode
that couples to the emitter via the overlying panel dielectric. When a finger touches the panel the
field coupling is changed, and touch is detected. The drive electrode (or drive line) used for
QMatrix charge transfer is labeled as the X line. The receiver electrode (or receive line) used for
QMatrix charge transfer is labeled as the Y line.
QMatrix circuits offer good immunity to moisture films, extreme levels of temperature stability,
superb low power characteristics, and small IC package sizes for a given key count.
5.2.3
5.3 Global settings common to all sensors of a specific acquisition
The touch sensing using QTouch library could be fine tuned by using a number of configurable
settings. This section explains the settings that are common to all sensors of a specific acquisition
method like QMatrix or QTouch.
method
Sensor schematics for a QMatrix acquisition method design
Atmel MCU
Figure 5-5 : Schematics for a QMatrix acquisition method design
YmA
YmB
SMP
Y0A
Y0B
Vref
X0
Xn
RYB0
CS0
...
CSm
RYBm
RYm
RX0
RXn
RY0
...
...
Typical values:
RX: 1k
RY: 1k
CS: 4.7nF
RYB: 470k
----------------------------------
Port-pin count =
n + (2 * m) + 2
n – number of X lines
m – number of Y lines
----------------------------------
Port requirements:
X: Configurable I/O pin
YA:Configurable I/O pin (*)
YB: ADC port (*)
SMP: Configurable I/O pin
Vref: AIN0 (Comparator)
(*): The port I/O pin should
be in consecutive order
Sensor
Sensor
0,0
n,0
Sensors,
X,Y
Sensor
Sensor
0,m
n,m
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