Note the following details of the code protection feature on Microchip devices:
YSTEM
CERTIFIED BY DNV
== ISO/TS 16949==
•Microchip products meet the specification contained in their particular Microchip Data Sheet.
•Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.
•There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.
•Microchip is willing to work with the customer who is concerned about the integrity of their code.
•Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable.”
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.
Information contained in this publication regarding device
applications and the like is provided only for your convenience
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
MICROCHIP MAKES NO REPRESENTATIONS OR
WARRANTIES OF ANY KIND WHETHER EXPRESS OR
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OTHERWISE, RELATED TO THE INFORMATION,
INCLUDING BUT NOT LIMITED TO ITS CONDITION,
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Trademarks
The Microchip name and logo, the Microchip logo, dsPIC,
K
logo, rfPIC and UNI/O are registered trademarks of
Microchip Technology Incorporated in the U.S.A. and other
countries.
FilterLab, Hampshire, HI-TECH C, Linear Active Thermistor,
MXDEV, MXLAB, SEEVAL and The Embedded Control
Solutions Company are registered trademarks of Microchip
Technology Incorporated in the U.S.A.
Analog-for-the-Digital Age, Application Maestro, chipKIT,
chipKIT logo, CodeGuard, dsPICDEM, dsPICDEM.net,
dsPICworks, dsSPEAK, ECAN, ECONOMONITOR,
FanSense, HI-TIDE, In-Circuit Serial Programming, ICSP,
Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB,
MPLINK, mTouch, Omniscient Code Generation, PICC,
PICC-18, PICDEM, PICDEM.net, PICkit, PICtail, REAL ICE,
rfLAB, Select Mode, Total Endurance, TSHARC,
UniWinDriver, WiperLock and ZENA are trademarks of
Microchip Technology Incorporated in the U.S.A. and other
countries.
SQTP is a service mark of Microchip Technology Incorporated
in the U.S.A.
All other trademarks mentioned herein are property of their
respective companies.
DS41393B-page 2Preliminary 2009-2012 Microchip Technology Inc.
ISBN: 9781620761366
Microchip received ISO/TS-16949:2009 certification for its worldwide
headquarters, design and wafer fabrication facilities in Chandler and
Tempe, Arizona; Gresham, Oregon and design centers in California
and India. The Company’s quality system processes and procedures
are for its PIC
devices, Serial EEPROMs, microperipherals, nonvolatile memory and
analog products. In addition, Microchip’s quality system for the design
and manufacture of development systems is ISO 9001:2000 certified.
®
MCUs and dsPIC® DSCs, KEELOQ
®
code hopping
Page 3
AR1000 SERIES RESISTIVE TOUCH
SCREEN CONTROLLER
AR1000 Series Resistive Touch Screen Controller
Special Features:
• RoHS Compliant
• Power-Saving Sleep mode
• Industrial Temperature Range
• Built-in Drift Compensation Algorithm
• 128 Bytes of User EEPROM
Power Requirements:
• Operating Voltage: 2.5-5.0V ±5%
• Standby Current:
- 5V: 85 uA, typical; 125 uA (maximum)
- 2.5V: 40 uA, typical; 60 uA (maximum)
• Operating “No touch” Current:
- 3.0 mA (typical)
• Operating “Touch” Current:
- 17 mA, typical, with a touch sensor having
200 layers.
- Actual current is dependent on the touch
sensor used
• AR1011/AR1021 Brown-Out Detection (BOR) set
to 2.2V.
Touch Modes:
• Off, Stream, Down, Up and more.
Touch Sensor Support:
• 4-Wire, 5-Wire and 8-Wire Analog Resistive
• Lead-to-Lead Resistance: 50-2,000typical)
• Layer-to-Layer Capacitance: 0-0.5 uF
• Touch Sensor Time Constant: 500 us (maximum)
Touch Resolution:
• 10-bit Resolution (maximum)
Touch Coordinate Report Rate:
• 140 Reports Per Second (typical) with a Touch
Sensor of 0.02 uF with 200 Layers
• Actual Report Rate is dependent on the Touch
Sensor used.
2.0Basics of Resistive Sensors......................................................................................................................................................... 7
C Communications .................................................................................................................................................................. 17
Index .................................................................................................................................................................................................... 65
The Microchip Web Site....................................................................................................................................................................... 67
Customer Change Notification Service ................................................................................................................................................ 67
Customer Support ................................................................................................................................................................................ 67
It is our intention to provide our valued customers with the best documentation possible to ensure successful use of your Microchip
products. To this end, we will continue to improve our publications to better suit your needs. Our publications will be refined and
enhanced as new volumes and updates are introduced.
If you have any questions or comments regarding this publication, please contact the Marketing Communications Department via
E-mail at docerrors@microchip.com or fax the Reader Response Form in the back of this data sheet to (480) 792-4150. We
welcome your feedback.
Most Current Data Sheet
To obtain the most up-to-date version of this data sheet, please register at our Worldwide Web site at:
http://www.microchip.com
You can determine the version of a data sheet by examining its literature number found on the bottom outside corner of any page.
The last character of the literature number is the version number, (e.g., DS30000A is version A of document DS30000).
Errata
An errata sheet, describing minor operational differences from the data sheet and recommended workarounds, may exist for current
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To determine if an errata sheet exists for a particular device, please check with one of the following:
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When contacting a sales office, please specify which device, revision of silicon and data sheet (include literature number) you are
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DS41393B-page 4Preliminary 2009-2012 Microchip Technology Inc.
Page 5
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
20
19
18
17
16
15
14
13
12
11
V
SS
XX+
5WSX-
YY+
SX+
SDI/SDA/RX
NC
SCK/SCL/TX
1
2
3
4
5
6
7
8
9
10
V
DD
M1
SYM2
WAKE
SIQ
SY+
SS
SDO
NC
AR1000 Series (SSOP, SOIC)
20
19
18
17
16
15
14
13
12
11
X+
5WSX-
YY+
SX+
1
2
3
4
5
6
789
10
SY-
M1
M2
WAKE
SIQ
SY+
SS
VDD
VSS
X-
SDO
NC
SCK/SCL/TX
NC
SDI/SDA/RX
AR1000 Series (QFN)
1.0DEVICE OVERVIEW
The Microchip mTouchTM AR1000 Series Resistive
Touch Screen Controller is a complete, easy to
integrate, cost-effective and universal touch screen
controller chip.
The AR1000 Series has sophisticated proprietary
touch screen decoding algorithms to process all touch
data, saving the host from the processing overhead.
Providing filtering capabilities beyond that of other
low-cost devices, the AR1000 delivers reliable, validated, and calibrated touch coordinates.
Using the on-board EEPROM, the AR1000 can store
and independently apply the calibration to the touch
coordinates before sending them to the host. This
unique combination of features makes the AR1000 the
most resource-efficient touch screen controller for
system designs, including embedded system
integrations.
FIGURE 1-1:BLOCK DIAGRAM
1.1Applications
The AR1000 Series is designed for high volume, small
form factor touch solutions with quick time to market
requirements – including, but not limited to:
DS41393B-page 6Preliminary 2009-2012 Microchip Technology Inc.
Page 7
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
2.0BASICS OF RESISTIVE
SENSORS
2.1Terminology
ITO (Indium Tin Oxide) is the resistive coating that
makes up the active area of the touch sensor. ITO is a
transparent semiconductor that is sputtered onto the
touch sensor layers.
Flex or Film or Topsheet
user touches. Flex refers to the fact that the top layer
physically flexes from the pressure of a touch.
Stable or Glass
interfaces against the display.
Spacer Adhesive
the flex and stable layers together around the perimeter
of the sensor.
Spacer Dots
separation between the flex and stable layers. The dots
are typically printed onto the stable layer.
is a frame of adhesive that connects
maintain physical and electrical
is the top sensor layer that a
is the bottom sensor layer that
Bus Bars or Silver Frit electrically connect the ITO on
the flex and stable layers to the sensor’s interface tail.
Bus bars are typically screen printed silver ink. They
are typically much lower in resistivity than the ITO.
is the left and right direction on the touch sensor.
X-Axis
is the top and bottom direction on the touch
Y-Ax is
sensor.
Drive Lines
sensor.
supply a voltage gradient across the
2.2General
Resistive 4, 5, and 8-wire touch sensors consist of two
facing conductive layers, held in physical separation
from each other. The force of a touch causes the top
layer to deflect and make electrical contact with the
bottom layer.
Touch position measurements are made by applying a
voltage gradient across a layer or axis of the touch
sensor. The touch position voltage for the axis can be
measured using the opposing layer.
A comparison of typical sensor constructions is shown
below in Tabl e 2 -1 .
TABLE 2-1:SENSOR COMPARISON
SensorComments
4-WireLess expensive than 5-wire or 8-wire
Lower power than 5-wire
More linear (without correction) than 5-wire
Touch inaccuracies occur from flex layer damage or resistance changes
5-WireMaintains touch accuracy with flex layer damage
Inherent nonlinearity often requires touch data correction
Touch inaccuracies occur from resistance changes
8-WireMore expensive than 4-wire
Lower power than 5-wire
More linear (without correction) than 5-wire
Touch inaccuracies occur from flex layer damaged
Maintains touch accuracy with resistance changes
The AR1000 Series Resistive Touch Screen
Controllers will work with any manufacturers of analog
resistive 4, 5 and 8-wire touch screens. The
communications and decoding are included, allowing
the user the quickest simplest method of interfacing
analog resistive touch screens into their applications.
The AR1000 Series was designed with an
understanding of the materials and processes that
make up resistive touch screens. The AR1000 Series
Touch Controller is not only reliable, but can enhance
the reliability and longevity of the resistive touch
screen, due to its advanced filtering algorithms and
wide range of operation.
A 4-wire resistive touch sensor consists of a stable and
flex layer, electrically separated by spacer dots. The
layers are assembled perpendicular to each other. The
touch position is determined by first applying a voltage
gradient across the flex layer and using the stable layer
to measure the flex layer’s touch position voltage. The
second step is applying a voltage gradient across the
stable layer and using the flex layer to measure the
stable layer’s touch position voltage.
The measured voltage at any position across a driven
axis is predictable. A touch moving in the direction of
the driven axis will yield a linearly changing voltage. A
touch moving perpendicular to the driven axis will yield
a relatively unchanging voltage (See Figure 2-1).
FIGURE 2-1:4-WIRE DECODING
DS41393B-page 8Preliminary 2009-2012 Microchip Technology Inc.
Page 9
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
2.48-Wire Sensor
An 8-wire resistive touch sensor consists of a stable
and flex layer, electrically separated by spacer dots.
The layers are assembled perpendicular to each other.
The touch position is determined by first applying a
voltage gradient across the flex layer and using the
stable layer to measure the flex layer’s touch position
voltage. The second step is applying a voltage gradient
across the stable layer and using the flex layer to
measure the stable layer’s touch position voltage.
The measured voltage at any position across a driven
axis is predictable. A touch moving in the direction of
the driven axis will yield a linearly changing voltage. A
touch moving perpendicular to the driven axis will yield
a relatively unchanging voltage.
FIGURE 2-2:8-WIRE DECODING
The basic decoding of an 8-wire sensor is similar to a
4-wire. The difference is that an 8-wire sensor has four
additional interconnects used to reference sensor
voltage back to the controller.
A touch system may experience voltage losses due to
resistance changes in the bus bars and connection
between the controller and sensor. The losses can vary
with product use, temperature, and humidity. In a
4-wire sensor, variations in the losses manifest themselves as error or drift in the reported touch location.
The four additional sense lines found on 8-wire sensors
are added to dynamically reference the voltage to correct for this fluctuation during use (See Figure 2-2).
A 5-wire resistive touch sensor consists of a flex and
stable layer, electrically separated by spacer dots. The
touch position is determined by first applying a voltage
gradient across the stable layer in the X-axis direction
and using the flex layer to measure the axis touch position voltage. The second step is applying a voltage gradient across the stable layer in the Y-axis direction and
using the flex layer to measure the axis touch position
voltage.
The voltage is not directly applied to the edges of the
active layer, as it is for 4-wire and 8-wire sensors. The
voltage is applied to the corners of a 5-wire sensor.
FIGURE 2-3:5-Wire Decoding
To measure the X-axis, the left edge of the layer is
driven with 0V (ground), using connections to the upper
left and lower left sensor corners. The right edge is
driven with +5 V
right and lower right sensor corners.
To measure the Y-axis, the top edge of the layer is
driven with 0V (ground), using connections to the upper
left and upper right sensor corners. The bottom edge is
driven with +5 V
and lower right sensor corners.
The measured voltage at any position across a driven
axis is predictable. A touch moving in the direction of
the driven axis will yield a linearly changing voltage. A
touch moving perpendicular to the driven axis will yield
a relatively unchanging voltage (See Figure 2-3).
DC, using connections to the upper
DC, using connections to the lower left
DS41393B-page 10Preliminary 2009-2012 Microchip Technology Inc.
Page 11
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
3.0HARDWARE
3.1Main Schematic
A main application schematic for the SOIC/SSOP
package pinout is shown in Figure 3-1.
The desired sensor type of 4/8-wire or 5-wire is
hardware selectable using pin M2.
TABLE 3-1:4/8-WIRE vs. 5-WIRE
SELECTION
TypeM2 pin
4/8-wireV
5-wireVDD
If 4/8-wire has been hardware-selected, then the
choice of 4-wire or 8-wire is software-selectable via the
TouchOptions Configuration register.
When 4/8-wire is hardware-selected, the controller
defaults to 4-wire operation. If 8-wire operation is
desired, then the TouchOptions Configuration register
must be changed.
SS
3.34-Wire Touch Sensor Interface
Sensor tail pinouts can vary by manufacturer and part
number. Ensure that both sensor tail pins for one
sensor axis (layer) are connected to the controller’s
X-/X+ pins and the tail pins for the other sensor axis
(layer) are connected to the controller’s Y-/Y+ pins. The
controller’s X-/X+ and Y-/Y+ pin pairs do not need to
connect to a specific sensor axis. The orientation of
controller pins X- and X+ to the two sides of a given
sensor axis is not important. Likewise, the orientation of
controller pins Y- and Y+ to the two sides of the other
sensor axis is not important.
Connections to a 4-wire touch sensor are as follows
(See Figure 3-2).
FIGURE 3-2:4-WIRE TOUCH SENSOR INTERFACE
Tie unused controller pins 5WSX-, SX+, SY-, and SY+
to V
SS.
See Section 3.8 “ESD Considerations” and
Section 3.9 “Noise Considerations” for important
information regarding the capacitance of the controller
schematic hardware.
DS41393B-page 12Preliminary 2009-2012 Microchip Technology Inc.
Page 13
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
3.45-Wire Touch Sensor Interface
Sensor tail pinouts can vary by manufacturer and part
number. Ensure sensor tail pins for one pair of
diagonally related sensor corners are connected to the
controller’s X-/X+ pins and the tail pins for the other pair
of diagonally related corners are connected to the
controller’s Y-/Y+ pins.
The controller’s X-/X+ and Y-/Y+ pin pairs do not need
to connect to a specific sensor axis. The orientation of
controller pins X- and X+ to the two selected diagonal
sensor corners is not important.
Likewise, the orientation of controller pins Y- and Y+ to
the other two selected diagonal sensor corners is not
important. The sensor tail pin connected to its top layer
must be connected to the controller’s 5WSX- pin.
Connections to a 5-wire touch sensor are shown in
Figure 3-3 below.
FIGURE 3-3:5-WIRE TOUCH SENSOR INTERFACE
Tie unused controller pins SX+, SY-, and SY+ to VSS.
See “Section 3.8 “ESD Considerations” and
Section 3.9 “Noise Considerations” for important
information regarding the capacitance of the controller
schematic hardware.
Sensor tail pinouts can vary by manufacturer and part
number. Ensure both sensor tail pins for one sensor
axis (layer) are connected to the controller’s X-/X+ pins
and the tail pins for the other sensor axis (layer) are
connected to the controller’s Y-/Y+ pins.
The controller’s X-/X+ and Y-/Y+ pin pairs do not need
to connect to a specific sensor axis. The orientation of
controller pins X- and X+ to the two sides of a given
sensor axis is not important. Likewise, the orientation of
controller pins Y- and Y+ to the two sides of the other
sensor axis is not important.
The 8-wire sensor differs from a 4-wire sensor in that
each edge of an 8-wire sensor has a secondary
connection brought to the sensor’s tail. These
secondary connections are referred to as “sense” lines.
The controller pins associated with the sense line for an
8-wire sensor contain an ‘S’ prefix in their respective
names. For example, the SY- pin is the sense line
connection associated with the main Y- pin connection.
Consult with the sensor manufacturer ’s specification to
determine which member of each edge connected pair
is the special 8-wire “sense” connection. Incorrectly
connecting the sense and excite lines to the controller
will adversely affect performance.
The controller requires that the main and “sense” tail
pin pairs for sensor edges be connected to controller
pin pairs as follows:
• Y- and SY-
• Y+ and SY+
• X- and 5WSX-
• X+ and SX+
Connections to a 8-wire touch sensor are shown in
Figure 3-4 below.
FIGURE 3-4:8-WIRE TOUCH SENSOR INTERFACE
See Section 3.8 “ESD Considerations” and
Section 3.9 “Noise Considerations” for important
information regarding the capacitance of the controller
schematic hardware.
DS41393B-page 14Preliminary 2009-2012 Microchip Technology Inc.
Page 15
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
3.6Status LED
The LED and associated resistor are optional.
FIGURE 3-5:
The LED serves as a status indicator that the controller
is functioning. It will slow flash when the controller is
running with no touch in progress. It will flicker quickly
(mid-level on) when a touch is in progress.
If the LED is used with SPI communication, then the
LED will be off with no touch and flicker quickly
(mid-level on) when a touch is in progress.
Note:If the SIQ pin is not used, it must be left as
a No Connect and NOT tied to circuit V
SS.
V
DD or
3.7 WAKE Pin
The AR1000’s WAKE pin is described as “Touch
Wake-Up/Touch Detection”. It serves the following
three roles in the controller’s functionality:
• Wake-up from touch
• Touch detection
• Measure sensor capacitance
The application circuit shows a 20 KΩ resistor
connected between the WAKE pin and the X- pin on the
controller chip. The resistor is required for product
operation, based on all three of the above roles.
3.8ESD Considerations
ESD protection is shown on the 4-wire, 5-wire, and
8-wire interface applications schematics.
The capacitance of alternate ESD diodes may
adversely affect touch performance. A lower
capacitance is better. The PESD5V0S1BA parts shown
in the reference design have a typical capacitance of 35
pF. Test to ensure that selected ESD protection does
not degrade touch performance.
ESD protection is shown in the reference design, but
acceptable protection is dependent on your specific
application. Ensure your ESD solution meets your
design requirements.
3.9Noise Considerations
Touch sensor filtering capacitors are included in the
reference design.
Warning: Changing the value of the capacitors may
adversely affect performance of the touch system.
Note 1:These parameters are characterized but not tested.
2:At 10 mA.
3:At –4 mA.
SS≤VIL≤ 0.2*VDD
0.8*VDD≤VIH≤ VDD
0.8*VDD≤VIH≤ VDD
4.3 Addressing
The AR1021’s device ID 7-bit address is: 0x4D
(0b1001101)
TABLE 4-3:I2C DEVICE ID ADDRESS
Device ID Address, 7-bit
A7A6A5A4A3A2A1
1001101
TABLE 4-4:I2C DEVICE WRITE ID
ADDRESS
A7A6A5A4A3 A2 A1 A0
1 0 0110100x9A
TABLE 4-5:I2C DEVICE READ ID
A7A6A5A4 A3 A2 A1 A0
1 0 0110110x9B
4.4Master Read Bit Timing
Master read is to receive touch reports and command
responses from the AR1021.
• Address bits are latched into the AR1021 on the
rising edges of SCL.
• Data bits are latched out of the AR1021 on the
rising edges of SCL.
• ACK is presented (by AR1021 for address, by
master for data) on the ninth clock.
• The master must monitor the SCL pin prior to
asserting another clock pulse, as the AR1021
may be holding off the master by stretching the
clock.
—
SS≤VOL
(1.25*VDD – 2.25V)
Open-drain
(1)
≤ (1.2V – 0.15*VDD)
ADDRESS
(3)
≤ VOH
(1)
≤ VDD
(2)
FIGURE 4-1:I2C MASTER READ BIT TIMING DIAGRAM
Steps
1.SCL and SDA lines are Idle high.
2.Master presents “Start” bit to the AR1021 by
taking SDA high-to-low, followed by taking SCL
high-to-low.
3.Master presents 7-bit Address, followed by a
R/W = 1 (Read mode) bit to the AR1021 on
SDA, at the rising edge of eight master clock
(SCL) cycles.
DS41393B-page 18Preliminary 2009-2012 Microchip Technology Inc.
4.AR1021 compares the received address to its
device ID. If they match, the AR1021
acknowledges (ACK) the master sent address
by presenting a low on SDA, followed by a
low-high-low on SCL.
5.Master monitors SCL, as the AR1021 may be
“clock stretching”, holding SCL low to indicate
that the master should wait.
Page 19
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
6.Master receives eight data bits (MSb first)
presented on SDA by the AR1021, at eight
sequential master clock (SCL) cycles. The data
is latched out on SCL falling edges to ensure it
is valid during the subsequent SCL high time.
7.If data transfer is not complete, then:
- Master acknowledges (ACK) reception of the
eight data bits by presenting a low on SDA,
followed by a low-high-low on SCL.
- Go to step 5.
8.If data transfer is complete, then:
- Master acknowledges (ACK) reception of the
eight data bits and a completed data transfer
by presenting a high on SDA, followed by a
low-high-low on SCL.
9.Master presents a “Stop” bit to the AR1021 by
taking SCL low-high, followed by taking SDA
low-to-high.
4.5Master Write Bit Timing
Master write is to send supported commands to the
AR1021.
• Address bits are latched into the AR1021 on the
rising edges of SCL.
• Data bits are latched into the AR1021 on the
rising edges of SCL.
• ACK is presented by AR1021 on the ninth clock.
• The master must monitor the SCL pin prior to
asserting another clock pulse, as the AR1021
may be holding off the master by stretching the
clock.
FIGURE 4-2:I2C MASTER WRITE BIT TIMING DIAGRAM
Steps
1.SCL and SDA lines are Idle high.
2.Master presents “Start” bit to the AR1021 by
taking SDA high-to-low, followed by taking SCL
high-to-low.
3.Master presents 7-bit Address, followed by a
R/W = 0 (Write mode) bit to the AR1021 on
SDA, at the rising edge of eight master clock
(SCL) cycles.
4.AR1021 compares the received address to its
device ID. If they match, the AR1021
acknowledges (ACK) the master sent address
by presenting a low on SDA, followed by a
low-high-low on SCL.
5.Master monitors SCL, as the AR1021 may be
“clock stretching”, holding SCL low to indicate
the master should wait.
6.Master presents eight data bits (MSb first) to the
AR1021 on SDA, at the rising edge of eight master clock (SCL) cycles.
7.AR1021 acknowledges (ACK) receipt of the
eight data bits by presenting a low on SDA, followed by a low-high-low on SCL.
8.If data transfer is not complete, then go to step 5.
9.Master presents a “Stop” bit to the AR1021 by
taking SCL low-high, followed by taking SDA
low-to-high.
4.6Clock Stretching
The master normally controls the clock line SCL. Clock
stretching is when the slave device holds the SCL line
low, indicating to the master that it is not ready to
continue the communications.
During communications, the AR1021 may hold off the
master by stretching the clock with a low on SCL.
The master must monitor the slave SCL pin to ensure
the AR1021 is not holding it low, prior to asserting
another clock pulse for transmitting or receiving.
4.7AR1020 Write Conditions
The AR1020 part does not implement clock stretching
on write conditions.
A 50 us delay is needed before the Stop bit, when
clocking a command to the AR1020.
Touch coordinates, when available, are provided to the
master by the AR1021 in the following protocol (See
Figure 4-3).
FIGURE 4-3:I2C TOUCH REPORT PROTOCOL
Note that the IRQ signal shown above occurs on the
SDO pin of the AR1021.
4.9Command Protocol
The master issues supported commands to the
AR1021 in the following protocol.
Below is an example of the ENABLE_TOUCH command
(see Figure 4-4).
FIGURE 4-4:I2C COMMAND PROTOCOL
Note that the IRQ shown above occurs on the SDO pin.
• 0x9AAR1021 Device ID address
• 0x00Protocol command byte (send 0x00 for
the protocol command register)
• 0x55Header
• 0x01Data size
• 0x12Command
4.10Sleep State
Pending communications are not maintained through a
sleep/wake cycle.
If the SDO pin is asserted for a pending touch report or
command response, and the AR1021 enters a Sleep
state, prior to the master performing a read on the data,
then the data is lost.
DS41393B-page 20Preliminary 2009-2012 Microchip Technology Inc.
Page 21
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
5.0SPI COMMUNICATIONS
SPI operates in Slave mode with an Idle low SCK and
data transmitted on the SCK falling edge.
5.1SPI Hardware Interface
A summary of the hardware interface pins is shown
below in Tab le 5 - 1.
TABLE 5-1:SPI HARDWARE INTERFACE
AR1021 PinDescription
M1Connect to V
SDISerial data sent from master
SCKSerial clock to master
SDOSerial data to master SPI
SIQ
SS
SCKPin
• The AR1021 controller’s SCL/SCK/TX pin
receives Serial Clock (SCK), controlled by the
host.
• The Idle state of the SCK should be low.
• Data is transmitted on the falling edge of SCK.
SDI Pin
• The AR1021 controller’s SDI/SDA/RX pin reads
Serial Data Input (SDI), sent by the host.
SDO Pin
• The AR1021 controller’s SDO pin presents Serial
Data Output (SDO) to the host.
Interrupt output to master (optional)
Slave Select (optional)
DD to select SPI communications
SIQ Pin
• The AR1021 controller’s SIQ pin provides an
optional interrupt output from the controller to the
host.
• The SIQ pin is asserted high when the controller
has data available (a touch report or a command
response) for the host.
• The SIQ pin is deasserted after the host clocks
out the first byte of the data packet.
Note:The AR1000 Development kit PICkit™
Serial Pin 1 is designated for the SIQ
interrupt pin after the firmware updated is
executed for the PICkit.
SS Pin
• The AR1021 controller’s SS pin provides optional
“slave select” functionality.
SS Pin LevelAR1021 Select
VSS
VDD
In the ‘inactive’ state, the controller’s SDO pin presents
a high-impedance in order to prevent bus contention
with another device on the SPI bus.
The SPI standard does not specify a maximum data
rate for the serial bus. In general, SPI data rates can be
in MHz. Peripherals devices, such as the AR1021
controller, specify their own unique maximum SPI data
rates.
The maximum SPI bit rate for the AR1021 controller is
~900 kHz.
Characterization has been performed at bit rates of ~39
kHz and ~156 kHz.
FIGURE 5-4:SPI BIT TIMING – DETAIL
5.7.2INTER-BYTE DELAY
The AR1021 controller requires an inter-byte delay of
~50 us. This means the host should wait ~50 us
between the end of clocking a given byte and the start
of clocking the next byte.
5.7.3BIT TIMING – DETAIL
Characterized timing details are shown below, in
Figure 5-4.
TABLE 5-3:SPI BIT TIMING MIN. AND MAX. VALUES
Parameter Number
10SS↓ (select) to SCK↑ (initial)500—ns
11SCK high550—ns
12SCK low550—ns
13SCK↓ (last) to SS↑ (deselect)800—ns
14SDI setup before SCK↓100—ns
15SDI hold after SCK↓100—ns
16SDO valid after SCK↓—150ns
17SDO↑ rise—50ns
18SDO↓ fall—50ns
19SS↑ (deselect) to SDO High-z1050ns
Note 1:Parameters are characterized, but not tested.
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Parameter DescriptionMin.Max.Units
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
6.0UART COMMUNICATIONS
TABLE 6-1:UART HARDWARE INTERFACE
AR1011 PinDescription
M1Connect M1 to V
TXTransmit to host
RXReceive from host
SDOConnect SDO to V
UART communication is fixed at 9600 baud rate, 8N1
format.
Sleep mode will cause the TX line to drop low, which
may appear as a 0x00 byte sent from the controller.
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
7.0TOUCH REPORTING
PROTOCOL
Touch coordinates are sent from the controller to the
host system in a 5-byte data packet, which contains the
X-axis coordinate, Y-axis coordinate, and a “Pen-Up/
Down” touch status.
The range for X-axis and Y-axis coordinates is from 04095 (12-bit). The realized resolution is 1024, and bits
X1:X0 and Y1:Y0 are zeros.
It is recommended that applications be developed to
read the 12-bit coordinates from the packet and use
them in a 12-bit format. This enhances the application
robustness, as it will work with either 10 or 12 bits of
coordinate information.
The touch coordinate reporting protocol is shown below
in Tab le 7 -1 .
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
8.0CONFIGURATION REGISTERS
The Configuration registers allow application specific
customization of the controller. The default values have
been optimized for most applications and are
automatically used, unless you choose to change
them.
Unique sensors and/or product applications may
benefit from adjustment of Configuration registers.
Note:Although most registers can be
configured for a value ranging from 0 to
255, using a value outside the specified
range for the specific register may
negatively impact performance.
8.1Restoring Default Parameters
• AR1010/AR1020
The factory default settings for the Configuration
registers can be recovered by writing a value of 0xFF
to address 0x00 of the EEPROM, then cycling power.
• AR1011/AR1021
The factory default settings for the Configuration
registers can be recovered by writing a value of 0xFF
to addresses 0x01 and 0x29 of the EEPROM, then
cycling power.
The TouchThreshold register sets the threshold for a
touch condition to be detected as a touch. A touch is
detected if it is below the TouchThreshold setting. Too
small of a value might prevent the controller from
accepting a real touch, while too large of a value might
allow the controller to accept very light or false touch
conditions. Valid values are as follows:
0 ≤ TouchThreshold ≤ 255
8.2.2SensitivityFilter Register (OFFSET
0x03)
The SensitivityFilter register sets the level of touch sensitivity. A higher value is more sensitive to a touch
(accepts a lighter touch), but may exhibit a less stable
touch position. A lower value is less sensitive to a touch
(requires a harder touch), but will provide a more stable
touch position. Valid values are as follows:
0 ≤ SensitivityFilter ≤ 10
8.2.3SamplingFast Register (OFFSET
0x04)
The SamplingFast register sets the level of touch measurement sample averaging, when touch movement is
determined to be fast. See the SpeedThreshold register for information on the touch movement threshold. A
lower value will provide for a higher touch coordinate
reporting rate when touch movement is fast, but may
exhibit more high-frequency random noise error in the
touch position. A higher value will reduce the touch
coordinate reporting rate when touch movement is fast,
but will reduce high-frequency random noise error in
the touch position. Valid values are as follows:
SamplingFast: <1, 4, 8, 16, 32, 64, 128>
Recommended Values: <4, 8, 16>
Higher values may improve accuracy with some
sensors.
8.2.4SamplingSlow Register (OFFSET
0x05)
The SamplingSlow register sets the level of touch measurement sample averaging, when touch movement is
slow. See the SpeedThreshold register for information
on the touch movement threshold. A lower value will
increase the touch coordinate reporting rate when the
touch motion is slow, but may exhibit a less stable more
jittery touch position. A higher value will decrease the
touch coordinate reporting rate when the touch motion
is slow, but will provide a more stable touch position.
Valid values are as follows:
SamplingSlow: 1, 2, 4, 8, 16, 32, 64, 128
8.2.5AccuracyFilterFast Register (OFFSET
0x06)
The AccuracyFilterFast register sets the level of an
accuracy enhancement filter, used when the touch
movement is fast. See the SpeedThreshold register for
information on the touch movement threshold. A lower
value will provide better touch coordinate resolution
when the touch motion is fast, but may exhibit more
low-frequency noise error in the touch position. A
higher value will reduce touch coordinate resolution
when the touch motion is fast, but will reduce low-frequency random noise error in the touch position. Valid
values are as follows:
1 ≤ AccuracyFilterFast ≤ 8
Higher values may improve accuracy with some
sensors.
8.2.6AccuracyFilterSlow Register
(OFFSET 0x07)
The AccuracyFilterSlow register sets the level of an
accuracy enhancement filter, used when the touch
movement is slow. See the SpeedThreshold register for
information on the touch movement threshold. A lower
value will provide better touch coordinate resolution
when the touch motion is slow, but may exhibit more
low-frequency noise error in the touch position. A
higher value will reduce touch coordinate resolution
when the touch motion is slow, but will reduce low-frequency random noise error in the touch position. Valid
values are as follows:
1 ≤ AccuracyFilterSlow ≤ 8
8.2.7SpeedThreshold Register (OFFSET
0x08)
The SpeedThreshold register sets the threshold for
touch movement to be considered as slow or fast. A
lower value reduces the touch movement speed that
will be considered as fast. A higher value increases the
touch movement speed that will be considered as fast.
Valid values are as follows:
0 ≤ SpeedThreshhold ≤ 255
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
8.2.8SleepDelay Register (OFFSET 0x0A)
The SleepDelay register sets the time duration with no
touch or command activity that will cause the controller
to enter a low-power Sleep mode. Valid values are as
follows:
0 ≤ SleepDelay ≤ 255
Sleep Delay Time = SleepDelay * 100 ms; when SleepDelay > 0
A value of zero disables the Sleep mode, such that the
controller will never enter low-power Sleep mode.
A touch event will wake the controller from low-power
Sleep mode and start sending touch reports. Communications sent to the controller will wake it from the lowpower Sleep mode and initiate action to the command.
8.2.9PenUpDelay Register (OFFSET
0x0B)
The PenUpDelay register sets the duration of a pen-up
event that the controller will allow, without sending a
pen-up report for the event. The delay time is started
upon detecting a pen-up condition.
If a pen down is reestablished before the delay time
expires, then pen-down reports will continue without a
pen up being sent. This effectively debounces a touch
event in process.
A lower value will make the controller more responsive
to pen ups, but will cause more touch drop outs with a
lighter touch. A higher value will make the controller
less responsive to pen ups, but will reduce the number
of touch drop outs with a lighter touch. Valid values are
as follows:
0 ≤ PenUpDelay ≤ 255
Pen-up Delay Time ≈ PenUpDelay * 240 μs
8.2.10TouchMode Register (OFFSET 0x0C)
The TouchMode register configures the action taken for
various touch states.
There are three states of touch for the controller’s touch
reporting action which can be independently controlled.
Touch States:
1.Pen Down (initial touch)
User defined 0-3 touch reports, with selectable pen
states.
2.Pen Movement (touch movement after initial
touch)
User defined no-touch reports or streaming touch
reports, with selectable pen states.
3.Pen Up (touch release)
User defined 0-3 touch reports, with selectable pen
states.
Every touch report includes a “P” (Pen) bit that
indicates the pen state.
R = Readable bitW = Writable bitU = Unimplemented bit, read as ‘0’
bit 7-5PD<2:0>: Pen-Down State bits (action taken upon pen down).
000 = No touch report
001 = Touch report with P=0
010 = Touch report with P=1
011 = Touch report with P=1, then touch report with P=0
100 = Touch report with P=0, then touch report with P=1, then touch report with P=0
101 = Touch report with P=0, then touch report with P=1
bit 4-3PM<1:0>: Pen Movement State bits (action taken upon pen movement).
00 = No touch report
01 = Touch report with P=0
10 = Touch report with P=1
bit 2-0PU<2:0>: Pen-Up State bits (action taken upon pen up).
000 = No touch report
001 = Touch report with P=0
010 = Touch report with P=1
011 = Touch report with P=1, then touch report with P=0
100 = Touch report with P=0, then touch report with P=1, then touch report with P=0
101 = Touch report with P=0, then touch report with P=1
A couple of typical setup examples for the TouchMode
are as follows:
• Report a pen down P=1 on initial touch, followed
by reporting a stream of pen downs P=1 during
the touch, followed by a final pen up P=0 on touch
release. TouchMode = 0b01010001 = 0x51
• Report a pen up P=0 then a pen down P=1 on
initial touch, followed by reporting a stream of pen
downs P=1 during the touch, followed by a final
pen up P=0 on touch release. TouchMode =
0b10110001 = 0xB1
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
Location of Calibration
Targets presented during
Calibration.
12.5% of
Full Scale
12.5% of
Full Scale
8.2.11TouchOptions Register (OFFSET
0x0D)
The TouchOptions register contains various “touch”
related option bits.
REGISTER 8-2:TouchOptions REGISTER
U-0U-0U-0U-0U-0U-0R/WR/W
——————48WCCE
bit 7bit 0
Legend:
R = Readable bitW = Writable bitU = Unimplemented bit, read as ‘0’
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 4wire. 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.
8.2.12CalibrationInset Register (OFFSET
0x0E)
The CalibrationInset register defines the expected
position of the calibration points, inset from the perimeter 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 020% with 0.5% resolution
For example, CalibrationInset = 25 (0x19) yields a calibration 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
The PenStateReportDelay register sets the delay time
between sending of sequential touch reports for the
“Pen-Down” and “Pen-Up” Touch mode states. See
Section 8.2.10 “TouchMode Register (offset 0x0C)”
for touch modes.
For example, if “Pen-Up” state of the TouchMode
register is configured to send a touch report with P=1,
followed by a touch report with P=0, then this delay
occurs between the two touch reports. This provides
some timing flexibility between the two touch reports
that may be desired in certain applications. Valid values
are as follows.
0 ≤ PenStateReportDelay ≤ 255
Pen State Report Delay Time = PenStateReportDelay *
50 μs
8.2.14TouchReportDelay Register (OFFSET
0x11)
The TouchReportDelay register sets a forced delay
time between successive touch report packets. This
allows slowing down of the touch report rate, if desirable for a given application. For example, a given application may not need a high rate of touch reports and
may want to reduce the overhead used to service all of
the touch reports being sent. In this situation, increasing the value of this register will reduce the rate at
which the controller sends touch reports. Valid values
are as follows:
0 ≤ TouchReportDelay ≤ 255
Touch Report Delay Time ≈ TouchReportDelay * 500 μs
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
9.0COMMANDS
9.1Sending Commands
9.1.1COMMAND SEND FORMAT
The controller supports application-specific
configuration commands as shown in Tab le 9 - 1, below.
TABLE 9-1:COMMAND SEND FORMAT
Byte #NameValueDescription
1Header0x55Header (mark beginning of command packet)
2Size0x<>Size, # of bytes following this byte
3Command0x<>Command ID
4Data0x<>Data, if applicable for the command
:Data0x<>Data, if applicable for the command
To ensure command communication is not interrupted
by touch activity, it is recommended that the controller
touch is disabled, prior to other commands. This can be
done as follows:
1.Send DISABLE_TOUCH command
2.Wait 50 ms
3.Send desired commands
4.Send ENABLE_TOUCH command
9.1.2COMMAND RESPONSE
A received command will be responded to as seen in
Table 9-2 below.
TABLE 9-2:COMMAND RESPONSE FORMAT
Byte #NameValueDescription
1Header0x55Header (mark beginning of command packet)
2Size0x<>Size, # of bytes following this byte
3Status0x<>Status
4Command0x<>Command ID
5Data0x<>Data, if applicable for the command
:Data0x<>Data, if applicable for the command
The “Status” value within the response packet should
be one of the following (See Table 9-3):
9.1.3DISABLE TOUCH BEFORE
SENDING SUBSEQUENT
COMMANDS
The AR1000 does not support full duplex
communications. It cannot send touch reports to the
host simultaneously with receiving commands from the
host.
Disable AR1000 touch reporting prior to sending any
other command(s), then re-enable touch reporting
when complete with executing other commands.
1.Send the DISABLE_TOUCH command.
Check for expected command response.
2.Send a desired command.
Check for expected command response.
3.Repeat at step 2 if another command is to be
sent.
4.Send the ENABLE_TOUCH command.
Check for expected command response.
9.1.4CONFIRM COMMAND IS SENT
Confirm each command sent to the AR1000, prior to
issuing another command, to ensure it is executed.
This is accomplished by evaluating the AR1000
response to a command that has been sent to it.
Check for each of the following five conditions to be
met (See Ta bl e 9 -4 ).
TABLE 9-4:COMMAND RESPONSE ERROR CONDITIONS
ConditionResponse ByteDescription
Header1Header 0x55 value is expected
Size2Size 0x<> value to match what is expected for command sent
Status3Status 0x00 “success” value is expected
ID4Command ID 0x<> value to match what is expected (ID of sent command)
Data5 to endData byte count to match what is expected for command sent
0x<> represents a value that is dependent on the command.
An error has occurred if no response is received at all
or if any of the above conditions are not met in the
response from the AR1000. If an error condition
occurs, delay for a period of ~50 ms then send the
same command again.
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
9.2AR1000 Commands
TABLE 9-5:COMMAND SET SUMMARY
Command
Val ue
0x10GET_VERSION
0x12ENABLE_TOUCH
0x13DISABLE_TOUCH
0x14CALIBRATE_MODE
0x20REGISTER_READ
0x21REGISTER_WRITE
0x22REGISTER_START_ADDRESS_REQUEST
0x23REGISTERS_WRITE_TO_EEPROM
0x28EEPROM_READ
0x29EEPROM_WRITE
0x2BEEPROM_WRITE_TO_REGISTERS
9.3AR1000 Command Descriptions
9.3.1GET_VERSION – 0x10
Controller will return version number and type.
Send: <0x55><0x01><0x10>
Receive: <0x55><0x05><Response><0x10><Ver-
sion High><Version Low><Type>
where <Type>
Command Description
REGISTER 9-1:GET_VERSION <TYPE> FORMAT
R/WR/WR/WR/WR/WR/WR/WR/W
RS1RS0TP5TP4TP3TP2TP1TP0
bit 7bit 0
Legend:
R = Readable bitW = Writable bitU = Unimplemented bit, read as ‘0’
bit 7-6RS<1:0>: Resolution of Touch Coordinates bits
00 = 8-bit
01 = 10-bit
10 = 12-bit
bit 5-0TP<5:0>: Type of Controller bits
001010 = ARA10
9.3.2ENABLE_TOUCH – 0x12
Controller will send touch coordinate reports for valid
touch conditions.
Send: <0x55><0x01><0x12>
Receive: <0x55><0x02><Response><0x12>
9.3.3DISABLE_TOUCH – 0x13
Controller will not send any touch coordinate reports. A
touch will, however, still wake-up the controller if
asleep.
Enter Calibration mode. This instructs the controller to
enter a mode of accepting the next four touches as the
calibration point coordinates. See Section 10.1 “Cali-
bration of Touch Sensor with Controller” for an
example.
Completion of Calibration mode will automatically store
the calibration point coordinates in on-board controller
memory and set (to 1) the CCE bit of the TouchOptions
register. This bit enables the controller to report touch
coordinates that have been processed with the
previously collected calibration data.
To provide for proper touch orientation, the four
sequential calibration touches must be input in the
physical order on the touch sensor, as shown in
Figure 9-1.
FIGURE 9-1:CALIBRATION ROUTINE
SEQUENCE
Upon completion, the controller’s register values and
calibration data are stored to the EEPROM.
The Calibration mode will be cancelled by sending any
command before the mode has been completed. If the
calibration is canceled, the controller response may
appear incorrect or incomplete. This is expected
behavior.
DS41393B-page 38Preliminary 2009-2012 Microchip Technology Inc.
<0x55><0x02><0x00><0x14>Response for touch of Calibration point #1
<0x55><0x02><0x00><0x14>Response for touch of Calibration point #2
<0x55><0x02><0x00><0x14>Response for touch of Calibration point #3
<0x55><0x02><0x00><0x14>Response for touch of Calibration point #4
A successful CALIBRATE command results in 5
response packets being sent to the host.
Once the response has been received for the
completed 4
implemented prior to sending any commands to the
controller. This one second delay insures all data has
been completely written to the EEPROM.
9.3.4.3Calibration Data Encoded and
Stored in EEPROM
System integrators may prefer to pre-load a calibration
into their design. This allows the user to properly
navigate to the calibration routine icon or shortcut
without the use of a mouse. This also addresses the
need to calibrate each system individually before
deploying it to the field.
Separator Upper Left (Node 1) Upper Right (Node 2) Lower Right (Node 3)Lower Left (Node 4)Flip State
XY X YX Y X Y
LoHiLoHiLoHiLoHiLoHiLoHiLoHiLoHi
Decode the above data to as follows:
1.Swap the order of stored low and high bytes for
a given coordinate.
2.Convert the 16-bit value (stored high and low
bytes) from hexadecimal to decimal.
3.Divide the result by 64 to properly rescale the
16-bit stored value back to a 10-bit significant
coordinate.
Example of Low = 0x40 and High = 0xF3:
Swap: 0xF340
Hex to Decimal: 62272
Divide by 64: 973
The raw touch coordinates, decoded by the controller,
for each of the four calibration touches are extrapolated
if CalibrationInset was non-zero. The four coordinate
pairs are then re-oriented, if required, such that the
upper left corner is the minimum (X,Y) “origin” value
pair and the lower right corner is the maximum (X,Y)
value pair.
Coordinates are 10-bit significant values, scaled to
16-bit and stored in a High (Hi) and Low (Lo) byte pair.
REGISTER 9-2:Flip State Byte
U-0U-0U-0U-0U-0R/WR/WR/W
—————XYFLIPXFLIPYFLIP
bit 7bit 0
Legend:
R = Readable bitW = Writable bitU = Unimplemented bit, read as ‘0’
bit 7-3Unimplemented: Read as ‘0’
bit 2XYFLIP: X and Y Axis Flip bit
1 = X and Y axis are flipped
0 = X an Y axis are not flipped
bit 1XFLIP: X-Axis Flip bit
1 = X-axis flipped
0 = X-axis not flipped
bit 0YFLIP:Y-Axis Flip bit
1 = Y-axis flipped
0 = Y-axis not flipped
For storing desired calibration values to the EEPROM:
• AR1010/AR1020 (See Section 9.3.12 “EEPROM
Map”).
• AR1011/AR1021 (See Section 9.3.12 “EEPROM
Map” andSection 10.2 “AR1011/AR1021 Storing Default Calibration Values to EEPROM”).
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
9.3.5REGISTER_READ – 0x20
Reads a value from a controller register location. This
can be used to determine a controller configuration
setting.
Configuration registers are defined as an Offset value
from the Start address for the register group. Read a
register as follows:
Issue the
1.
command to obtain the Start address for the
register group
2.Calculate the desired register’s absolute
address by adding the register’s Offset value to
Start address for the register group.
3.Issue this
follows, using the calculated register ’s absolute
address:
Send: <0x55><0x04><0x20><Register Address
Receive: <0x55><0x02 + # of Registers
The AR1000 controller will ignore the value entered for
the Register Address High Byte. However, 0x00 is
recommended to safeguard against any possible future
product development.
REGISTER_START_ADDRESS_REQUEST
.
REGISTER_READ
High byte><Register Address Low
byte><# of Registers to Read>
Write a value to a controller register location. This can
be used to change a controller configuration setting.
Configuration registers are defined as an Offset value
from the Start address for the register group. Write a
register as follows:
Issue the
1.
command to obtain the Start address for the
register group.
2.Calculate the desired register’s absolute
address by adding the register’s Offset value to
Start address for the register group.
3.Issue this REGISTER_WRITE command, as
follows, using the calculated register ’s absolute
address:
Send: <0x55><0x04 + # Registers to
Receive: <0x55><0x02><Response><0x21>
REGISTER_START_ADDRESS_REQUEST
Write><0x21><Register Address High
byte><Register Address Low byte>
<# of Registers to
Write><Data>…<Data>
Register Address High byte: 0x00
# of Registers to Read: 0x01 thru 0x08
The AR1000 controller will ignore the value entered for
the Register Address High Byte. However, 0x00 is
recommended to safeguard against any possible future
product development.
9.3.7
REGISTER_START_ADDRESS_REQUEST
– 0x22
Configuration registers are defined as an Offset value
from the Start address for the register group. This
command returns the Start address for the register
group.
The AR1000 controller will ignore the value entered for
the EEPROM Address High Byte. However, 0x00 is
recommended to safeguard against any possible future
product development.
This command provides a means to write values to the
user space within the EEPROM.
• The first 128 bytes (address range 0x00-0x7F)
are reserved by the controller for the Configuration register settings and calibration data. Only the
Register Write to EEPROM command should be
used to write Configuration registers to EEPROM.
Failure to use the Register Write command to
save Configuration registers to EEPROM may
result in failures or reverting to previously stored
Configuration register values.
• The second 128 bytes (address range
0x80-0xFF) are provided for the user’s application, if desired.
Warning: ONLY write to user EEPROM addresses of
0x80-0xFF.
One of the following actions is required for
EEPROM changes to be used by the
controller:
• The controller power must be cycled
from OFF to ON or
• Issue the
EEPROM_WRITE_TO_REGISTERS
command.
Write to EEPROM as follows:
Send: <0x55><0x04 + # EEPROM to
Write><0x29><EEPROM Address High
byte><EEPROM Address Low byte>
<# of EEPROM to
Write><Data>…<Data>
Register Address High byte: 0x00
# of Registers to Read: 0x01 thru 0x08
Receive: <0x55><0x02><Response><0x29>
The AR1000 controller will ignore the value entered for
the EEPROM Address High Byte. However, 0x00 is
recommended to safeguard against any possible future
product development.
9.3.11EEPROM_WRITE_TO_REGISTERS –
0x2B
Write applicable EEPROM data to Configuration registers. This will cause the controller to immediately begin
using changes made to EEPROM stored Configuration
register values. A power cycle of the controller will
automatically cause the controller to use changes
made to the EEPROM stored Configuration register
values, without the need for issuing this command. This
command eliminates the need for the power cycle.
Send: <0x55><0x01><0x2B>
Receive: <0x55><0x02><Response><0x2B>
9.3.12 EEPROM MAP
The first 128 bytes in address range 0x00:0x7F are
reserved by the controller for the Configuration register
settings and calibration data. The mapping of data in
this reserved controller space of the EEPROM may
change over different revisions within the product
lifetime.
The EEPROM_WRITE command must not be used to
write directly to the lower 128 bytes of the controller
EEPROM space of 0x00:0x7F.
The second 128 bytes in address range 0x80:0xFF are
provided for the user’s application, if desired.
TABLE 9-6:AR1010/AR1020 EEPROM
AND REGISTER MAP
EEPROM AddressFunction
0x00<Special Use>
0x01<Special Use>
0x02<Special Use>
0x03Touch Threshold
0x04Sensitivity Filter
0x05Sampling Fast
0x06Sampling Slow
0x07Accuracy Filter Fast
0x08Accuracy Filter Slow
0x09Speed Threshold
0x0A<Special Use>
0x0BSleep Delay
0x0CPen-Up Delay
0x0DTouch Mode
0x0ETouch Options
0x0FCalibration Inset
0x10Pen State Report Delay
0x11<Reserved>
0x12Touch Report Delay
0x13<Special Use>
0x14Data Block Separator
0x15Calibration UL X-low
0x16Calibration UL X-high
0x17Calibration UL Y-low
0x18Calibration UL Y-high
0x19Calibration UR X-low
0x1ACalibration UR X-high
0x1BCalibration UR Y-low
0x1CCalibration UR Y-high
0x1DCalibration LR X-low
0x1ECalibration LR X-high
0x1FCalibration LR Y-low
DS41393B-page 42Preliminary 2009-2012 Microchip Technology Inc.
DS41393B-page 44Preliminary 2009-2012 Microchip Technology Inc.
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
Touch and
Release Target
Touch and
Release Target
10.0APPLICATION NOTES
10.1Calibration of Touch Sensor with
Controller
The reported coordinates from a touch screen
controller are typically calibrated to the application’s
video display. The task is often left up to the host to
perform. This controller provides a feature for it to send
coordinates that have already been calibrated, rather
than the host needing to perform this task. If enabled,
the feature will apply pre-collected 4-point calibration
data to the reported touch coordinates. Calibration only
accounts for X and Y directional scaling. It does not
correct for angular errors due to rotation of the touch
sensor on the video display.
The calibration process can be cancelled at anytime by
sending a command to the controller.
Upon completion of the calibration process, the
calibration data is automatically stored to the EEPROM
and “Calibrated Coordinates” is enabled.
The process of “calibration” with the controller is
described below.
1.Disable touch reporting by issuing <Disable
Touch> command.
Send: <0x55><0x01><0x13>
Receive: <0x55><0x02><Response><0x13>
2.Get register group Start address by issuing
REGISTER_START_ADDRESS_REQUEST
command.
A register Start address of 0x20 is used below, for
this example.
Send: <0x55><0x01><0x22>
Receive: <0x55><0x03><0x00><0x22><0x20>
3.Calculate the CalibrationInset register’s address
by adding its offset value of 0x0E to the register
group Start address of 0x20.
5.Set the Calibration Inset by writing the desired
value to the CalibrationInset register.
Send:<0x55><0x05><0x21><0x00><0x2E><0x01
><0x19>
Receive: <0x55><0x02><0x00><0x21>
6.Issue the CALIBRATE_MODE command.
Send: <0x55><0x02><0x14><0x04>
Receive: <0x55><0x02><0x00><0x14>
7.Software must display the first calibration point
target in the upper left quadrant of the display
and prompt the user to touch and release the
target.
FIGURE 10-1:SUGGESTED TEXT FOR
FIRST CALIBRATION
TARGET
8.Wait for the user to touch and release the first
calibration point target. Do this by looking for a
controller response of:
<0x55><0x02><0x00> <0x14>
9.Software must display the second calibration
point target in the upper right quadrant of the
display and prompt the user to touch and
release the target.
FIGURE 10-2:SUGGESTED TEXT FOR
SECOND CALIBRATION
TARGET
10. Wait for the user to touch and release the
second calibration point target. Do this by
looking for a controller response of:
11. Software must display the third calibration point
target in the lower right quadrant of the display
and prompt the user to touch and release the
target.
FIGURE 10-3:SUGGESTED TEXT FOR
THIRD CALIBRATION
TARGET
12. Wait for the user to touch and release the third
calibration point target. Do this by looking for a
controller response of:
<0x55><0x02><0x00><0x14>
13. Software must display the fourth calibration
point target in the lower left quadrant of the
display and prompt the user to touch and
release the target.
FIGURE 10-4:SUGGESTED TEXT FOR
FOURTH CALIBRATION
TARGET
14. Wait for the user to touch and release the fourth
calibration point target. Do this by looking for a
controller response of:
<0x55><0x02><0x00><0x14>
15. Wait for the controller to correctly write
calibration data into EEPROM
• AR1010/AR1020: Wait one second for data to
be stored into EEPROM
• AR1011/AR1021: Wait for a controller
response of <0x55><0x02><0x00><0x14>
16. Enable touch reporting by issuing
ENABLE_TOUCH command.
Send: <0x55><0x01><0x12>
Receive: <0x55><0x02><Response><0x12>
DS41393B-page 46Preliminary 2009-2012 Microchip Technology Inc.
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
10.2AR1011/AR1021 Storing Default
Calibration Values to EEPROM
If you wish to implement fixed calibration values,
pre-loaded into the AR1000 EEPROM, then the
following procedure must be followed (See
Section 10.2.1 “Preparation for Fixed Calibration
Values”).
An example of calculating the checksum is shown
below (See Tab le 1 0- 1).
10.2.1PREPARATION FOR FIXED
CALIBRATION VALUES
Determine if fixed calibration values are suitable for
your application and determine your desired values.
Calculate a checksum for your custom data set. See
Section 9.3.4.3 “Calibration Data Encoded and
Stored in EEPROM” for additional details regarding
calibration data format.
TABLE 10-1:CHECKSUM CALCULATION EXAMPLE
DescriptionValueOperationChecksum Result
Seed0x45n/a0x45
Block Key0x550x45 + 0x55 =0x9A
Upper LeftXLow byte0x060x9A + 0x06 =0xA0
Upper LeftXHigh byte0x1B0xA0 + 0x1B =0xBB
Upper LeftYLow byte0xA50xBB + 0xA5 =0x60
Upper LeftYHigh byte0x080x60 + 0x08 =0x68
Upper RightXLow byte0x130x68 + 0x13 =0x7B
Upper RightXHigh byte0xDF0x7B + 0xDF =0x5A
Upper RightYLow byte0xF40x5A + 0xF4 =0x4E
Upper RightYHigh byte0x0B0x4E + 0x0B =0x59
Lower RightXLow byte0x980x59 + 0x98 =0xF1
Lower RightXHigh byte0xE40xF1 + 0xE4 =0xD5
Lower RightYLow byte0x1E0xD5 + 0x1E =0xF3
Lower RightYHigh byte0xEC0xF3 + 0xEC =0xDF
Lower LeftXLow byte0xBF0xDF + 0xBF =0x9E
Lower LeftXHigh byte0x1A0x9E + 0x1A =0xB8
Lower LeftYLow byte0x320xB8 + 0x32 =0xEA
Lower LeftYHigh byte0xE70xEA + 0xE7 =0xD1
Flip State0x010xD1 + 0x01 =0xD2
Checksum0xD2
The Checksum is an 8-bit value calculated by
successive additions with overflow ignored, as shown
below.
Checksum = 0x45
For each of the 18 calibration values, starting at the
Block Key and ending with the Flip State
1 = Enables calibrated coordinates, if the controller has been calibrated
0 = Disables calibrated coordinates
DS41393B-page 48Preliminary 2009-2012 Microchip Technology Inc.
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
1.Send the DISABLE_TOUCH (0x13) command.
2.Send the
REGISTER_START_ADDRESS_REQUEST
(0x22) to determine the absolute address for
TouchOptions Register.
3.Send the REGISTER_WRITE (0x21) command
to set the CCE bit of the TouchOptions Register.
4.Send REGISTERS_WRITE_TO_EEPROM (0x23)
command to have all current registers stored
into EEPROM.
5.Send the AR1000 ENABLE_TOUCH (0x12)
command.
The controller will use the stored calibration data after
cycling power to the controller.
10.2.4EEPROM_WRITE COMMAND TO
STORE DEFAULT CALIBRATION
The EEPROM_WRITE command is shown in this
section. SeeSection 9.0 “Commands” for more
command details.
<> = application specific value
Send to AR1000:
0x55Header
0x<>Number of bytes to follow this one
0x29Command ID
0x00Desired EEPROM address to write high
byte. Always 0x00
0x<>Desired EEPROM address to write low
byte
0x<>Number of consecutive EEPROM
addresses to write (supports 0x01 to 0x08)
0x<>Value # 1 to write
0x<>Value # 2 to write, if applicable
0x<>Value # 3 to write, if applicable
0x<>Value # 4 to write, if applicable
0x<>Value # 5 to write, if applicable
0x<>Value # 6 to write, if applicable
0x<>Value # 7 to write, if applicable
0x<>Value # 8 to write, if applicable
10.2.5QUALITY TEST
Although not required, a level of quality assurance can
be added to the process by the application issuing
multiple EEPROM_READ commands to the AR1000.
The response data from the EEPROM_READ commands
would be tested by the application against the
application’s desired data as a quality check.
10.2.6EXAMPLE COMMAND SEQUENCE
An example eight command sequence for the entire
process is shown below.
All values shown are in hexadecimal.
Calibration values are applications specific and have
been symbolically represented as follows:
DS41393B-page 50Preliminary 2009-2012 Microchip Technology Inc.
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
11.0ELECTRICAL SPECIFICATIONS
Absolute Maximum Ratings
Ambient temperature under bias.......................................................................................................-40°C to +125°C
Storage temperature ........................................................................................................................ -65°C to +150°C
Voltage on V
Voltage on all other pins with respect to V
Total power dissipation................................................................................................................................... 800 mW
Maximum current out of V
Maximum current into V
Input clamp current (V
Maximum output current sunk by any I/O pin.................................................................................................... 25 mA
Maximum output current sourced by any I/O pin .............................................................................................. 25 mA
† NOTICE: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the
device. This is a stress rating only and functional operation of the device at those or any other conditions above those
indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for
extended periods may affect device reliability.
† NOTICE: This device is sensitive to ESD damage and must be handled appropriately. Failure to properly handle
and protect the device in an application may cause partial to complete failure of the device.
DD with respect to VSS .................................................................................................... -0.3V to +6.5V
SS pin .................................................................................................................... 300 mA
DD pin ....................................................................................................................... 250 mA
I < 0 or VI > VDD) 20 mA
(†)
SS ........................................................................... -0.3V to (VDD + 0.3V)
The AR1000 series controller will operate down to 2.5V ± 5%. Touch performance will be optimized by using the highest allowable voltage for the design.
The PICkit Serial included in the AR1000 Development kit supports 3V-5V range of operation.
11.2AR1000 Electrical Characteristics
Operating Voltage: 2.5 ≤ VDD≤ 5.25V
FunctionPinInputOutput
M1M1V
SS≤VIL≤ 0.15*VDD
(0.25*VDD + 0.9V) ≤ VIH ≤ VDD
M2M2V
SS≤VIL≤ 0.15*VDD
(0.25*VDD + 0.9V) ≤ VIH ≤ VDD
SCL/SCKSCL/SCK/TXV
SS≤VIL≤ 0.2*VDD
0.8*VDD≤VIH≤ VDD
TXSCL/SCK/TX—V
SDISDI/SDA/RXVSS≤VIL≤ 0.2*VDD
0.8*VDD≤VIH≤ VDD
SDOSDO—V
—
—
—
SS≤VOL
(1)
≤ (1.2V – 0.15*VDD)
(1.25*VDD – 2.25V)
—
SS≤VOL
(1)
≤ (1.2V – 0.15*VDD)
(1.25*VDD – 2.25V)
(3)
≤ VOH
(3)
≤ VOH
(1)
≤ VDD
(1)
≤ VDD
(2)
(2)
SIQSIQ—VSS≤VOL
SDASDI/SDA/RXVSS≤VIL≤ 0.2*VDD
0.8*VDD≤VIH≤ VDD
RXSDI/SDA/RXV
SS≤VIL≤ 0.2*VDD
0.8*VDD≤VIH≤ VDD
SSSSV
SS≤VIL≤ 0.2*VDD
0.8*VDD≤VIH≤ VDD
Note 1:These parameters are characterized but not tested.
2:At 10 mA.
3:At -4 mA.
(1)
≤ (1.2V – 0.15*VDD)
(1.25*VDD – 2.25V)
Open-drain
—
—
(3)
≤ VOH
(1)
≤ VDD
(2)
DS41393B-page 52Preliminary 2009-2012 Microchip Technology Inc.
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
*Standard PICmicro® device marking consists of Microchip part number, year code, week code and
traceability code. For PICmicro device marking beyond this, certain price adders apply. Please check
with your Microchip Sales Office. For QTP devices, any special marking adders are included in QTP
price.
Legend: XX...XCustomer-specific information
YYear code (last digit of calendar year)
YYYear code (last 2 digits of calendar year)
WWWeek code (week of January 1 is week ‘01’)
NNNAlphanumeric traceability code
Pb-free JEDEC designator for Matte Tin (Sn)
*This package is Pb-free. The Pb-free JEDEC designator ()
can be found on the outer packaging for this package.
Note:In the event the full Microchip part number cannot be marked on one line, it will
be carried over to the next line, thus limiting the number of available
characters for customer-specific information.
*Standard PICmicro® device marking consists of Microchip part number, year code, week code and
traceability code. For PICmicro device marking beyond this, certain price adders apply. Please check
with your Microchip Sales Office. For QTP devices, any special marking adders are included in QTP
price.
Legend: XX...XCustomer-specific information
YYear code (last digit of calendar year)
YYYear code (last 2 digits of calendar year)
WWWeek code (week of January 1 is week ‘01’)
NNNAlphanumeric traceability code
Pb-free JEDEC designator for Matte Tin (Sn)
*This package is Pb-free. The Pb-free JEDEC designator ()
can be found on the outer packaging for this package.
Note:In the event the full Microchip part number cannot be marked on one line, it will
be carried over to the next line, thus limiting the number of available
characters for customer-specific information.
3
e
3
e
20-Lead QFN (4x4x0.9 mm)Example
PIN 1
PIN 1
I/ML
3
e
1042256
AR1021
12.2Package Marking Information (Continued)
DS41393B-page 54Preliminary 2009-2012 Microchip Technology Inc.
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
12.3Ordering
Note:The AR1011/AR1021 are recommended
for new designs. The AR1010/AR1020 are
still supported and available, but are not
recommended for new designs.
TABLE 12-1:ORDERING PART NUMBERS
Part Number
AR1011-I/MLUART-40°C to + 85°CQFN, 20 pinTube
AR1011-I/SOUART-40°C to + 85°CSOIC, 20 pinTube
AR1011-I/SSUART-40°C to + 85°CSSOP, 20 pinTube
AR1011T-I/MLUART-40°C to + 85°CQFN, 20 pinT/R
AR1011T-I/SOUART-40°C to + 85°CSOIC, 20 pinT/R
AR1011T-I/SSUART-40°C to + 85°CSSOP, 20 pinT/R
AR1021-I/MLI
AR1021-I/SOI
AR1021-I/SSI2CTM/SPI-40°C to + 85°CSSOP, 20 pinTube
AR1021T-I/MLI2CTM/SPI-40°C to + 85°CQFN, 20 pinT/R
AR1021T-I/SOI
AR1021T-I/SSI2CTM/SPI-40°C to + 85°CSSOP, 20 pinT/R
Communication
Typ e
2CTM
/SPI-40°C to + 85°CQFN, 20 pinTube
2CTM
/SPI-40°C to + 85°CSOIC, 20 pinTube
2CTM
/SPI-40°C to + 85°CSOIC, 20 pinT/R
Temp. RangePin PackagePacking
AR1010-I/MLUART-40°C to + 85°CQFN, 20 pinTube
AR1010-I/SOUART-40°C to + 85°CSOIC, 20 pinTube
AR1010-I/SSUART-40°C to + 85°CSSOP, 20 pinTube
AR1010T-I/MLUART-40°C to + 85°CQFN, 20 pinT/R
AR1010T-I/SOUART-40°C to + 85°CSOIC, 20 pinT/R
AR1010T-I/SSUART-40°C to + 85°CSSOP, 20 pinT/R
2CTM
AR1020-I/MLI
/SPI-40°C to + 85°CQFN, 20 pinTube
AR1020-I/SOI2CTM/SPI-40°C to + 85°CSOIC, 20 pinTube
AR1020-I/SSI2CTM/SPI-40°C to + 85°CSSOP, 20 pinTube
2CTM
AR1020T-I/MLI
/SPI-40°C to + 85°CQFN, 20 pinT/R
AR1020T-I/SOI2CTM/SPI-40°C to + 85°CSOIC, 20 pinT/R
AR1020T-I/SSI2CTM/SPI-40°C to + 85°CSSOP, 20 pinT/R
Modifying, removing or adding components may
adversely affect touch performance.
Specific manufacturers and part numbers are provided
only as a guide. Equivalents can be used.
TABLE B-1:BILL OF MATERIALS
LabelQuantityValueDescriptionManufacturerPart Number
C1110 uFCapacitor – Ceramic, 10 uF, 20%, 6.3V,
X7R, 0603
C210.1 uFCapacitor – Ceramic, 0.1 uF, 10%, 16V,
X7R, 0603
C3, C4, C5
D1-D8
R1120 KResistor – 20 K, 1/10W, 5%, 0603Yageo America RC0603JR-0720KL
U11N/ATouch controller ICMicrochipAR1011 or AR1021
Note 1:C5 is only needed for 5-wire applications.
See Section 3.8 “ESD Considerations” and Section 3.9 “Noise Considerations” for important information
regarding the capacitance of the controller schematic hardware.
(1)
2-30.01 uF Capacitor – Ceramic, 0.01 uF, 10%,
50V, X7R, 0603
(2)
2:D1-D8 are for ESD protection.
4-8130WDiode – Bidirectional, 130W, ESD
Protection, SOD323
- 4-wire touch screen, use D1-D4
- 5-wire touch screen, use D1-D5
- 8-wire touch screen, use D1-D8
AVX06036D106MAT2A
AVX0603YC104KAT2A
AVX06035C103KAT2A
NXPPESD5V0S1BA
DS41393B-page 64Preliminary 2009-2012 Microchip Technology Inc.
DS41393B-page 66Preliminary 2009-2012 Microchip Technology Inc.
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
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DS41393BAR1000 Series Resistive Touch Screen Controller
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DS41393B-page 68Preliminary 2009-2012 Microchip Technology Inc.