Datasheet

 2009-2012 Microchip Technology Inc. Preliminary DS41393B-page 33
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
8.2.11 TouchOptions Register (OFFSET
0x0D)
The TouchOptions register contains various “touch”
related option bits.
REGISTER 8-2: TouchOptions REGISTER
8.2.12 CalibrationInset Register (OFFSET
0x0E)
The CalibrationInset register defines the expected
position of the calibration points, inset from the perime-
ter of the touch sensor’s active area, by a percentage
of the full scale dimension.
This allows for the calibration targets to be placed inset
from edge to make it easier for a user to touch them.
The CalibrationInset register value is only used when
the CALIBRATION_MODE command is issued to the
controller. In Calibration mode, the controller will
extrapolate the calibration point touch report values by
the defined CalibrationInset percentage to achieve full
scale.
A software application that issues the
CALIBRATION_MODE command must present the
displayed calibration targets at the same inset
percentage as defined in this CalibrationInset register.
Valid values are as follows:
0 ≤ CalibrationInset ≤ 40
Calibration Inset = (CalibrationInset/2) %, Range of 0-
20% with 0.5% resolution
For example, CalibrationInset = 25 (0x19) yields a cal-
ibration inset of (25/2) or 12.5%. During the calibration
procedure, the controller will internally extrapolate the
calibration point touch values in Calibration mode by
12.5% to achieve full scale.
FIGURE 8-1:
U-0 U-0 U-0 U-0 U-0 U-0 R/W R/W
— — — — — — 48W CCE
bit 7 bit 0
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
bit 7-2 Unimplemented: Read as ‘0’
bit 1 48W: 4-Wire or 8-Wire Sensor Selection bit
1 = Selects 8-wire Sensor Operating mode
0 = Selects 4-wire Sensor Operating mode
bit 0 CCE: Calibrated Coordinates Enable bit
1 = Enables calibrated coordinates, if the controller has been calibrated
0 = Disables calibrated coordinates
Note: A 4-wire touch sensor will not work if the
48W Configuration bit is incorrectly
defined as 1, which selects 8-wire.
An 8-wire touch sensor will provide basic
operation if the 48W Configuration bit is
incorrectly defined as 0, which selects 4-
wire. However, the benefit of the 8-wire
sensor will only be realized if the 48W
Configuration bit is correctly defined as 1,
selecting 8-wire.
Location of Calibration
Targets presented during
Calibration.
12.5% of
Full Scale
12.5% of
Full Scale