ATAVRQTOUCHX Atmel, ATAVRQTOUCHX Datasheet - Page 19

• 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

hysteresis value) in order to avoid the sensor dither in and out of detect if the signal level is close
to original threshold level.
Setting
Hysteresis
5.4.3
The rotor or slider needs the position resolution (angle resolution in case of rotor and linear
resolution in case of slider) to be set. Resolution is the number of bits needed to report the
position of rotor or slider. It can have values from 2bits to 8 bits.
Setting
Position
Resoluti
on
5.4.4
In case of QMatrix, the rotor or slider needs the position hysteresis (angle hysteresis in case of
rotor and linear hysteresis in case of slider) to be set. It is the number of positions the user has to
move back, before touch position is reported when the direction of scrolling is changed and
during the first scrolling after the touch down.
Hysteresis can range from 0 (1 position) to 7 ( 8 positions). The hysteresis is carried out at 8 bits
resolution internally and scaled to desired resolution; therefore at resolutions lower than 8 bits
there might be a difference of 1 reported position from the hysteresis setting, depending on where
the touch is detected.
At lower resolutions, where skipping of the reported positions is observed, hysteresis can be set
to 0 (1 position). At Higher resolutions (6 ..8bits) , it would be recommended to have a hysteresis
of at least 2 positions or more.
NOTE:
It is not valid to have a hysteresis value more than the available bit positions in the resolution.
Ex: do not have a hysteresis value of 5 positions with a resolution of 2 bits (4 positions).
Setting
Position
Hysteresis
NOTE:
Position hysteresis is not valid (unused) in case of QTouch acquisition method libraries.
•
•
•
•
Position Resolution
Position Hysteresis
Setting of 0 = 50% of detect threshold value (HYST_50)
Setting of 1 = 25% of detect threshold value (HYST_25)
Setting of 2 = 12.5% of detect threshold value (HYST_12_5)
Setting of 3 = 6.25% of detect threshold value (HYST_6_25)
Variable
name
position_
resolution
Variable name
detect_hysteresis
Variable name
position_hysteresis
Data
Type
uint8_t
(3 bits)
Data Type
uint8_t (2 bits)
Unit
-
Data Type
uint8_t (3 bits)
Min
2 bits
Unit
Enum
Reported
position
0 – 3
Min
HYST_6_25
Unit
-
Max
8 bits
Min
0
Max
HYST_50
Reported
position
0-255
Max
7
Typical
HYST_6_25
Typical
3
Typica
l
8
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