AR1000 SERIES RESISTIVE TOUCH
SCREEN CONTROLLER
AR1000 Series Resistive Touch Screen Controller
Special Features
Touch Sensor Support
•
•
•
•
•
•
•
•
•
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 µA, typical; 125 µA (maximum)
- 2.5V: 40 µA, typical; 60 µA (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
4-Wire, 5-Wire and 8-Wire Analog Resistive
Lead-to-Lead Resistance: 50-2,000typical)
Layer-to-Layer Capacitance: 0-0.5 µF
Touch Sensor Time Constant: 500 µs (maximum)
Touch Resolution
• 10-bit Resolution (maximum)
Touch Coordinate Report Rate
• 140 Reports Per Second (typical) with a Touch
Sensor of 0.02 µF with 200 Layers
• Actual Report Rate is dependent on the Touch
Sensor used
Communications
•
•
•
SPI, Slave mode, p/n AR1021
I2C, Slave mode, p/n, AR1021
UART, 9600 Baud Rate, p/n AR1011
Touch Modes
• Off, Stream, Down, Up and more.
2009-2016 Microchip Technology Inc.
DS40001393C-page 1
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
Table of Contents
1.0 Device Overview .......................................................................................................................................................................... 3
2.0 Basics of Resistive Sensors ......................................................................................................................................................... 5
3.0 Hardware...................................................................................................................................................................................... 9
4.0 I2C Communications .................................................................................................................................................................. 14
5.0 SPI Communications .................................................................................................................................................................. 18
6.0 UART Communications .............................................................................................................................................................. 22
7.0 Touch Reporting Protocol ........................................................................................................................................................... 23
8.0 Configuration Registers .............................................................................................................................................................. 24
9.0 Commands ................................................................................................................................................................................. 30
10.0 Application Notes ....................................................................................................................................................................... 39
11.0 Electrical Specifications .............................................................................................................................................................. 45
12.0 Packaging Information................................................................................................................................................................ 47
Appendix A: Data Sheet Revision History............................................................................................................................................ 57
Appendix B: Device Differences........................................................................................................................................................... 58
The Microchip Website......................................................................................................................................................................... 59
Customer Change Notification Service ................................................................................................................................................ 59
Customer Support ................................................................................................................................................................................ 59
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DS40001393C-page 2
2009-2016 Microchip Technology Inc.
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
1.0
DEVICE OVERVIEW
1.1
The Microchip mTouch® 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
FIGURE 1-2:
PIN DIAGRAM
Applications
The AR1000 Series is designed for high volume, small
form factor touch solutions with quick time to market
requirements – including, but not limited to:
•
•
•
•
•
•
•
•
Mobile communication devices
Personal Digital Assistants (PDA)
Global Positioning Systems (GPS)
Touch Screen Monitors
KIOSK
Media Players
Portable Instruments
Point of Sale Terminals
AR1000 Series (QFN)
VDD
M1
SYM2
WAKE
SIQ
SY+
SS
SDO
NC
VSS
XX+
5WSXYY+
SX+
SDI/SDA/RX
NC
SCK/SCL/TX
2009-2016 Microchip Technology Inc.
20
19
18
17
16
15
14
13
12
11
1
2
3
4
5
M2
WAKE
SIQ
SY+
SS
6 SDO
7 NC
8 SCK/SCL/TX
9 NC
10 SDI/SDA/RX
1
2
3
4
5
6
7
8
9
10
SYM1
VDD
VSS
X-
20
19
18
17
16
AR1000 Series (SSOP, SOIC)
X+ 15
5WSX- 14
Y- 13
Y+ 12
SX+ 11
DS40001393C-page 3
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
TABLE 1-1:
PIN DESCRIPTIONS
Pin
Function
SSOP, SOIC
Description/Comments
QFN
1
18
VDD
Supply Voltage
2
19
M1
Communication Selection
3
20
SY-
Sense Y- (8-wire). Tie to VSS, if
not used.
4
1
M2
4/8-wire or 5-wire Sensor
Selection
5
2
WAKE
6
3
SIQ
LED Drive/SPI Interrupt. No
connect, if not used.
7
4
SY+
Sense Y+ (8-wire). Tie to VSS, if
not used.
8
5
SS
Slave Select (SPI). Tie to VSS, if
not used.
9
6
SDO
10
7
NC
11
8
SCK/SCL/TX
12
9
NC
13
10
SDI/SDA/RX
I2C Serial Data/SPI Serial Data
Input/UART Receive
14
11
SX+
Sense X+ (8-wire). Tie to VSS, if
not used.
15
12
Y+
Y+ Drive
16
13
Y-
Y- Drive
17
14
5WSX-
18
15
X+
X+ Drive
X- Drive
19
16
X-
20
17
VSS
DS40001393C-page 4
Touch Wake-up/Touch Detection
SPI Serial Data Output/I2C
Interrupt. Tie to Vss, if UART.
No connection. No connect or tie
to VSS or VDD.
SPI/I2C Serial Clock/UART
Transmit
No connection. No connect or tie
to VSS or VDD.
5W Sense (5-wire)/Sense X(8-wire). Tie to VSS, if not used.
Supply Voltage Ground
2009-2016 Microchip Technology Inc.
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
2.0
BASICS OF RESISTIVE
SENSORS
TABLE 2-1:
Sensor
2.1
Terminology
Less 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-Wire
Maintains touch accuracy with flex layer
damage
Inherent nonlinearity often requires touch
data correction
Touch inaccuracies occur from resistance
changes
8-Wire
More 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
Stable or Glass is the bottom sensor layer that
interfaces against the display.
Spacer Adhesive is a frame of adhesive that connects
the flex and stable layers together around the perimeter
of the sensor.
Spacer Dots maintain physical and electrical
separation between the flex and stable layers. The dots
are typically printed onto the stable layer.
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.
X-Axis is the left and right direction on the touch sensor.
Y-Axis is the top and bottom direction on the touch
sensor.
Drive Lines supply a voltage gradient across the
sensor.
2.2
General
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.
Comments
4-Wire
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 is the top sensor layer that a
user touches. Flex refers to the fact that the top layer
physically flexes from the pressure of a touch.
SENSOR COMPARISON
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.
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 Table 2-1.
2009-2016 Microchip Technology Inc.
DS40001393C-page 5
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
2.3
4-Wire Sensor
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:
DS40001393C-page 6
4-WIRE DECODING
2009-2016 Microchip Technology Inc.
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
2.4
8-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:
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).
8-WIRE DECODING
2009-2016 Microchip Technology Inc.
DS40001393C-page 7
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
2.5
5-Wire Sensor
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:
DS40001393C-page 8
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 VDC, using connections to the upper
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 VDC, using connections to the lower left
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).
5-Wire Decoding
2009-2016 Microchip Technology Inc.
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
3.0
HARDWARE
3.1
Main Schematic
A main application schematic for the SOIC/SSOP
package pinout is shown in Figure 3-1.
See Figure 1-2 for the QFN package pinout.
FIGURE 3-1:
MAIN SCHEMATIC (SOIC/SSOP PACKAGE PINOUT)
2009-2016 Microchip Technology Inc.
DS40001393C-page 9
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
3.2
4, 5, 8-Wire Sensor Selection
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
Type
M2 pin
4/8-wire
VSS
5-wire
VDD
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.
FIGURE 3-2:
3.3
4-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).
4-WIRE TOUCH SENSOR INTERFACE
Tie unused controller pins 5WSX-, 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.
DS40001393C-page 10
2009-2016 Microchip Technology Inc.
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
3.4
5-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.
2009-2016 Microchip Technology Inc.
DS40001393C-page 11
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
3.5
8-Wire Touch Sensor Interface
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.
FIGURE 3-4:
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 SYY+ and SY+
X- and 5WSXX+ and SX+
Connections to a 8-wire touch sensor are shown in
Figure 3-4 below.
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.
DS40001393C-page 12
2009-2016 Microchip Technology Inc.
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
3.6
Status LED
3.8
ESD Considerations
The LED and associated resistor are optional.
ESD protection is shown on the 4-wire, 5-wire, and
8-wire interface applications schematics.
FIGURE 3-5:
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.
LED SCHEMATIC
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:
3.7
If the SIQ pin is not used, it must be left as
a No Connect and NOT tied to circuit VDD or
VSS.
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.
3.9
Noise 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.
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.
2009-2016 Microchip Technology Inc.
DS40001393C-page 13
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
I2C COMMUNICATIONS
4.0
The AR1021 is an I2C slave device with a 7-bit address
of 0x4D, supporting up to 400 kHz bit rate.
A master (host) device interfaces with the AR1021.
I2C Hardware Interface
4.1
A summary of the hardware interface pins is shown
below in Table 4-1.
TABLE 4-1:
I2C HARDWARE INTERFACE
AR1021 Pin
Description
M1
Connect to VSS to select I2C communications
SCL
Serial Clock
SDA
Serial Data
SDO
Data ready interrupt output to master
M1 Pin
• The M1 pin must be connected to VSS to
configure the AR1021 for I2C communications.
SCL Pin
• The SCL (Serial Clock) pin is electrically
open-drain and requires a pull-up resistor,
typically 2.2 K to 10 K, from SCL to VDD.
• SCL Idle state is high.
SDA Pin
• The SDA (Serial Data) pin is electrically
open-drain and requires a pull-up resistor,
typically 2.2 K to 10 K, from SDA to VDD.
• SDA Idle state is high.
• Master write data is latched in on SCL rising
edges.
• Master read data is latched out on SCL falling
edges to ensure it is valid during the subsequent
SCL high time.
SDO Pin
• The SDO pin is a driven output interrupt to the
master.
• SDO Idle state is low.
• SDO will be asserted high when the AR1021 has
data ready (touch report or command response)
for the master to read.
DS40001393C-page 14
2009-2016 Microchip Technology Inc.
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
I2C Pin Voltage Level
Characteristics
4.2
I2C PIN VOLTAGE LEVEL CHARACTERISTICS
TABLE 4-2:
Function
Pin
Input
Output
SCL/SCK
SCL/SCK/TX
VSS ≤ VIL≤ 0.2*VDD
0.8*VDD ≤ VIH ≤ VDD
—
SDO
SDO
—
VSS ≤ VOL(1) ≤ (1.2V – 0.15*VDD)(2)
(1.25*VDD – 2.25V)(3) ≤ VOH(1) ≤ VDD
SDA
SDI/SDA/RX
VSS ≤ VIL ≤ 0.2*VDD
0.8*VDD ≤ VIH ≤ VDD
Open-drain
Note 1:
2:
3:
4.3
These parameters are characterized but not tested.
At 10 mA.
At –4 mA.
Addressing
The AR1021’s device ID 7-bit address is: 0x4D
(0b1001101)
Device ID Address, 7-bit
A6
A5
A4
A3
A2
A1
1
0
0
1
1
0
1
TABLE 4-4:
I2C
DEVICE WRITE ID
ADDRESS
A7
A6
A5
A4
A3
1
0
0
1
1
FIGURE 4-1:
A2 A1 A0
0
1
0
0x9A
A5
A4
A3
1
0
0
1
1
A2 A1 A0
0
1
1
0x9B
Master 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.
I2C MASTER READ BIT TIMING DIAGRAM
Steps
3.
A6
4.4
A7
I2C DEVICE READ ID
ADDRESS
A7
I2C DEVICE ID ADDRESS
TABLE 4-3:
1.
2.
TABLE 4-5:
SCL and SDA lines are Idle high.
Master presents “Start” bit to the AR1021 by
taking SDA high-to-low, followed by taking SCL
high-to-low.
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.
2009-2016 Microchip Technology Inc.
4.
5.
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.
Master monitors SCL, as the AR1021 may be
“clock stretching”, holding SCL low to indicate
that the master should wait.
DS40001393C-page 15
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.
FIGURE 4-2:
9.
4.5
Master presents a “Stop” bit to the AR1021 by
taking SCL low-high, followed by taking SDA
low-to-high.
Master 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.
I2C MASTER WRITE BIT TIMING DIAGRAM
Steps
4.6
1.
2.
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.
3.
4.
5.
6.
7.
8.
9.
SCL and SDA lines are Idle high.
Master presents “Start” bit to the AR1021 by
taking SDA high-to-low, followed by taking SCL
high-to-low.
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.
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.
Master monitors SCL, as the AR1021 may be
“clock stretching”, holding SCL low to indicate
the master should wait.
Master presents eight data bits (MSb first) to the
AR1021 on SDA, at the rising edge of eight
master clock (SCL) cycles.
AR1021 acknowledges (ACK) receipt of the
eight data bits by presenting a low on SDA,
followed by a low-high-low on SCL.
If data transfer is not complete, then go to step 5.
Master presents a “Stop” bit to the AR1021 by
taking SCL low-high, followed by taking SDA
low-to-high.
DS40001393C-page 16
Clock Stretching
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.
4.7
AR1020 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.
2009-2016 Microchip Technology Inc.
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
4.8
Touch Report Protocol
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.
4.9
Command 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.
4.10
• 0x9A
• 0x00
Pending communications are not maintained through a
sleep/wake cycle.
• 0x55
• 0x01
• 0x12
AR1021 Device ID address
Protocol command byte (send 0x00 for
the protocol command register)
Header
Data size
Command
2009-2016 Microchip Technology Inc.
Sleep State
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.
DS40001393C-page 17
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
5.0
SPI COMMUNICATIONS
SPI operates in Slave mode with an Idle low SCK and
data transmitted on the SCK falling edge.
5.1
SPI Hardware Interface
A summary of the hardware interface pins is shown
below in Table 5-1.
TABLE 5-1:
SPI HARDWARE INTERFACE
AR1021 Pin
Description
M1
Connect to VDD to select SPI communications
SDI
Serial data sent from master
SCK
Serial clock from master
SDO
Serial data to master SPI
SIQ
Interrupt output to master (optional)
SS
Slave Select (optional)
SCK Pin
SS Pin
• 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.
• The AR1021 controller’s SS pin provides optional
“slave select” functionality.
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.
SS Pin Level
AR1021 Select
VSS
Active
VDD
Inactive
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.
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.
DS40001393C-page 18
2009-2016 Microchip Technology Inc.
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
5.2
SPI Pin Voltage Level
Characteristics
TABLE 5-2:
SPI PIN VOLTAGE CHARACTERISTICS
Operating Voltage: 2.5V ≤ VDD ≤ 5.25V
Function
Pin
Input
Output
SCK
SCL/SCK/TX
VSS ≤ VIL ≤ 0.2*VDD
0.8*VDD ≤ VIH ≤ VDD
—
SDI
SDI/SDA/RX
VSS ≤ VIL ≤ 0.2*VDD
0.8*VDD ≤ VIH ≤ VDD
—
SDO
SDO
—
VSS ≤ VOL(1) ≤ (1.2V – 0.15*VDD)(2)
(1.25*VDD – 2.25V)(3) ≤ VOH(1) ≤ VDD
SIQ
SIQ
—
VSS ≤ VOL(1) ≤ (1.2V – 0.15*VDD)(2)
(1.25*VDD – 2.25V)(3) ≤ VOH(1) ≤ VDD
SS
SS
VSS ≤ VIL ≤ 0.2*VDD
0.8*VDD ≤ VIH ≤ VDD
Note 1:
2:
3:
5.3
These parameters are characterized but not tested.
At 10 mA.
At -4 mA.
Data Flow
5.4
Touch Report Protocol
SPI data is transferred by the host clocking the AR1021
controller’s Serial Clock (SCK) pin.
The AR1021 controller’s touch reporting is interrupt
driven:
Each host driven clock cycle simultaneously shifts a bit
of data into and out from the AR1021 controller:
• The AR1021 controller asserts the SIQ interrupt
pin high when it has a touch report ready.
• The host clocks out the bytes of the touch report
packet from the AR1021 controller.
• The AR1021 controller clears the SIQ interrupt pin
low, after the first byte of the touch report packet
has been clocked out by the host.
• Out from the AR1021 controller’s Serial Data Out
(SDO) line.
• Into the AR1021 controller’s Serial Data In (SDI)
line.
The data is shifted Most Significant bit (MSb) first.
If the host clocks data out from the AR1021 controller
when no valid data is available, then a byte value of
0x4d will be presented by the controller.
FIGURE 5-1:
The communication protocol for the AR1021 controller
reporting touches to the host as shown below in
Figure 5-1.
SPI TOUCH REPORT PROTOCOL
2009-2016 Microchip Technology Inc.
DS40001393C-page 19
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
5.5
Command Protocol
The AR1021 controller receives commands from the
host as follows:
• The host clocks the bytes of a command to the
AR1021 controller.
• The AR1021 controller asserts the SIQ interrupt
pin high when it is ready with a response to the
command sent by the host.
FIGURE 5-2:
5.6
• The host clocks out the bytes of the command
response from the AR1021 controller.
• The AR1021 controller clears the SIQ interrupt pin
low, after the first byte of the command response
has been clocked out by the host.
The communication protocol for the host sending the
ENABLE_TOUCH command to the AR1021 controller is
shown below in Figure 5-2.
SPI TIMING DIAGRAM – COMMAND PROTOCOL (ENABLE_TOUCH)
SPI Bit Timing – General
General timing waveforms are shown below in
Figure 5-3.
FIGURE 5-3:
DS40001393C-page 20
SPI GENERAL BIT TIMING WAVEFORM
2009-2016 Microchip Technology Inc.
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
5.7
Timing – Bit Details
5.7.1
BIT RATE
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.
5.7.2
INTER-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.
5.7.3
BIT TIMING – DETAIL
Characterized timing details are shown below, in
Figure 5-4.
Characterization has been performed at bit rates of ~39
kHz and ~156 kHz.
FIGURE 5-4:
TABLE 5-3:
SPI BIT TIMING – DETAIL
SPI BIT TIMING MIN. AND MAX. VALUES
Parameter Number(1)
Parameter Description
Min.
Max.
Units
SS↓ (select) to SCK↑ (initial)
500
—
ns
11
SCK high
550
—
ns
12
SCK low
550
—
ns
10
Note 1:
13
SCK↓ (last) to SS↑ (deselect)
800
—
ns
14
SDI setup before SCK↓
100
—
ns
15
SDI hold after SCK↓
100
—
ns
16
SDO valid after SCK↓
—
150
ns
17
SDO↑ rise
—
50
ns
18
SDO↓ fall
—
50
ns
19
SS↑ (deselect) to SDO High-z
10
50
ns
Parameters are characterized, but not tested.
2009-2016 Microchip Technology Inc.
DS40001393C-page 21
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
6.0
UART COMMUNICATIONS
TABLE 6-1:
UART HARDWARE INTERFACE
AR1011 Pin
Description
M1
Connect M1 to VDD to select UART communications
TX
Transmit to host
RX
Receive from host
SDO
Connect SDO to VSS
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.
DS40001393C-page 22
2009-2016 Microchip Technology Inc.
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
7.0
TOUCH 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 Table 7-1.
TABLE 7-1:
TOUCH COORDINATE REPORTING PROTOCOL
Byte #
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
1
1
R
R
R
R
R
R
P
2
0
X6
X65
X4
X3
X2
X1
X0
3
0
0
0
X11
X10
X9
X8
X7
4
0
Y6
Y5
Y4
Y3
Y2
Y1
Y0
5
0
0
0
Y11
Y10
Y9
Y8
Y7
where:
•
•
•
•
P: 0 Pen Up, 1 Pen Down
R: Reserved
X11-X0: X-axis coordinate
Y11-Y0: Y-axis coordinate
2009-2016 Microchip Technology Inc.
DS40001393C-page 23
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
8.0
CONFIGURATION REGISTERS
8.1
• AR1010/AR1020
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.
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
Unique sensors and/or product applications may
benefit from adjustment of Configuration registers.
Note:
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.
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.
TABLE 8-1:
Restoring Default Parameters
CONFIGURATION REGISTERS
Register Name
Address
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Offset
AR1010/
AR1020
Default
AR1011/
AR1021
Default
0x58
0x58
0x00
0x01
0x01
0x01
TouchThreshold
0x02
Value of: 0-255
0xC5
0xC5
SensitivityFilter
0x03
Value of: 0-255
0x04
0x04
SamplingFast
0x04
Value of: 1, 2, 4, 8, 16, 32, 64, 128
0x04
0x04
SamplingSlow
0x05
Value of: 1, 2, 4, 8, 16, 32, 64, 128
0x10
0x10
AccuracyFilterFast
0x06
Value of: 1-8
0x02
0x04
AccuracyFilterSlow
0x07
Value of: 1-8
0x08
0x08
SpeedThreshold
0x08
Value of: 0-255
0x04
0x04
0x09
0x23
0x23
SleepDelay
0x0A
Value of: 0-255
0x64
0x64
PenUpDelay
0x0B
Value of: 0-255
TouchMode
0x0C
PD2
—
PD1 PD0 PM1 PM0 PU2
—
—
—
—
—
0x80
0x80
PU0
0xB1
0xB1
48W CCE
0x00
0x00
0x19
0x19
PU1
TouchOptions
0x0D
CalibrationInset
0x0E
PenStateReportDelay
0x0F
Value of: 0-40
0xC8
0xC8
0x10
Value of: 0-255
0x03
0x03
TouchReportDelay
0x11
0x00
0x00
0x12
Value of: 0-255
0x00
0x00
Configuration registers are defined as an Offset value
from the Start address for the register group.
To read or write to a register, do the following:
• Issue the REGISTER_START_ADDRESS_REQUEST command to obtain the Start address for
the register group.
• Calculate the desired register’s absolute address
by adding the register’s Offset value to Start
address for the register group.
DS40001393C-page 24
• Issue the REGISTER_READ or REGISTER_WRITE
command, using the calculated register’s
absolute address.
Warning: Use of invalid register values will yield
unpredictable results.
2009-2016 Microchip Technology Inc.
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
8.2
8.2.1
Register Descriptions
TouchThreshold Register (OFFSET
0x02)
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
8.2.2
SensitivityFilter 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
8.2.3
SamplingFast 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:
Recommended Values:
Higher values may improve accuracy with some
sensors.
8.2.4
8.2.5
AccuracyFilterFast 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 lowfrequency random noise error in the touch position.
Valid values are as follows:
1 ≤ AccuracyFilterFast ≤ 8
Higher values may improve accuracy with some
sensors.
8.2.6
AccuracyFilterSlow 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 lowfrequency random noise error in the touch position.
Valid values are as follows:
1 ≤ AccuracyFilterSlow ≤ 8
8.2.7
SpeedThreshold 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
SamplingSlow 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
2009-2016 Microchip Technology Inc.
DS40001393C-page 25
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
8.2.8
SleepDelay Register (OFFSET 0x0A)
8.2.10
TouchMode Register (OFFSET 0x0C)
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:
The TouchMode register configures the action taken for
various touch states.
0 ≤ SleepDelay ≤ 255
Touch States:
Sleep Delay Time = SleepDelay * 100 ms; when SleepDelay > 0
1.
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.
8.2.9
PenUpDelay 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.
There are three states of touch for the controller’s touch
reporting action which can be independently controlled.
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.
• Pen Down: P = 1
• Pen Up:
P=0
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
DS40001393C-page 26
2009-2016 Microchip Technology Inc.
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
REGISTER 8-1:
TouchMode REGISTER FORMAT
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
PD2
PD1
PD0
PM1
PM0
PU2
PU1
PU0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
bit 7-5
PD: 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 4-3
PM: 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 2-0
PU: 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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DS40001393C-page 27
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
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 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.
8.2.12
CalibrationInset 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.
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 12.5% to achieve full scale.
FIGURE 8-1:
CALIBRATION TARGET
EXAMPLE
12.5% of
Full Scale
Location of Calibration
Targets presented during
Calibration.
12.5% of
Full Scale
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
DS40001393C-page 28
2009-2016 Microchip Technology Inc.
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
8.2.13
PenStateReportDelay Register
(OFFSET 0x0F)
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
8.2.14
TouchReportDelay 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
2009-2016 Microchip Technology Inc.
DS40001393C-page 29
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
9.0
COMMANDS
9.1
Sending Commands
9.1.1
COMMAND SEND FORMAT
The
controller
supports
application-specific
configuration commands as shown in Table 9-1, below.
TABLE 9-1:
COMMAND SEND FORMAT
Byte #
Name
Value
Description
1
Header
0x55
Header (mark beginning of command packet)
2
Size
0x
Size, # of bytes following this byte
3
Command
0x
Command ID
4
Data
0x
Data, if applicable for the command
:
Data
0x
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.
2.
3.
4.
Send DISABLE_TOUCH command
Wait 50 ms
Send desired commands
Send ENABLE_TOUCH command
9.1.2
COMMAND RESPONSE
A received command will be responded to as seen in
Table 9-2 below.
TABLE 9-2:
COMMAND RESPONSE FORMAT
Byte #
Name
Value
Description
1
Header
0x55
2
Size
0x
Size, # of bytes following this byte
3
Status
0x
Status
4
Command
0x
Command ID
5
Data
0x
Data, if applicable for the command
:
Data
0x
Data, if applicable for the command
Header (mark beginning of command packet)
The “Status” value within the response packet should
be one of the following (See Table 9-3):
TABLE 9-3:
COMMAND RESPONSE
STATUS VALUES
Status Value
Description
0x00
Success
0x01
Command Unrecognized
0x03
Header Unrecognized
0x04
Command Time Out (exceeded ~100
ms)
0xFC
Cancel Calibration mode
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
9.1.3
DISABLE 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.
3.
Repeat at step 2 if another command is to be
sent.
Send the ENABLE_TOUCH command.
Check for expected command response.
4.
Check for expected command response.
9.1.4
CONFIRM 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 Table 9-4).
TABLE 9-4:
COMMAND RESPONSE ERROR CONDITIONS
Condition
Response Byte
Description
Header
1
Header 0x55 value is expected
Size
2
Size 0x value to match what is expected for command sent
Status
3
Status 0x00 “success” value is expected
ID
4
Command ID 0x value to match what is expected (ID of sent command)
Data
5 to end
Data 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
9.2
AR1000 Commands
TABLE 9-5:
COMMAND SET SUMMARY
Command
Value
Command Description
0x10
GET_VERSION
0x12
ENABLE_TOUCH
0x13
DISABLE_TOUCH
0x14
CALIBRATE_MODE
0x20
REGISTER_READ
0x21
REGISTER_WRITE
0x22
REGISTER_START_ADDRESS_REQUEST
0x23
REGISTERS_WRITE_TO_EEPROM
0x28
EEPROM_READ
0x29
EEPROM_WRITE
0x2B
EEPROM_WRITE_TO_REGISTERS
9.3
AR1000 Command Descriptions
9.3.1
GET_VERSION – 0x10
Controller will return version number and type.
Send:
Receive:
where
REGISTER 9-1:
GET_VERSION FORMAT
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
RS1
RS0
TP5
TP4
TP3
TP2
TP1
TP0
bit 7
bit 0
Legend:
R = Readable bit
bit 7-6
W = Writable bit
U = Unimplemented bit, read as ‘0’
RS: Resolution of Touch Coordinates bits
00 = 8-bit
01 = 10-bit
10 = 12-bit
bit 5-0
TP: Type of Controller bits
001010 = ARA10
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
9.3.2
ENABLE_TOUCH – 0x12
Controller will send touch coordinate reports for valid
touch conditions.
Send:
Receive:
9.3.3
DISABLE_TOUCH – 0x13
Controller will not send any touch coordinate reports. A
touch will, however, still wake-up the controller if
asleep.
Send:
Receive:
9.3.4
CALIBRATE – 0x14
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 “Calibration 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
#1
Upper Left
#2
Upper Right
Touch Sensor
#4
Lower Left
#3
Lower Right
Upon completion, the controller’s register values and
calibration data are stored to the EEPROM.
The Calibration mode will be canceled 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.
2009-2016 Microchip Technology Inc.
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
9.3.4.1
Send:
AR1010/AR1020 Calibrate
Response
Calibration Type
Description
0x04
4 point
Receive:
for initial command response
Response for touch of Calibration point #1
Response for touch of Calibration point #2
Response for touch of Calibration point #3
Response for touch of Calibration point #4
A successful CALIBRATE command results in five
response packets being sent to the host.
Once the response has been received for the
completed 4th target, a delay of one second must be
implemented prior to sending any commands to the
controller. This one second delay insures all data has
been completely written to the EEPROM.
9.3.4.2
Send:
AR1011/AR1021 Calibrate
Response
Calibration Type
Description
0x04
4 point
Receive:
for initial command response
Response for touch of Calibration point #1
Response for touch of Calibration point #2
Response for touch of Calibration point #3
Response for touch of Calibration point #4
Response after EEPROM has been written
A successful CALIBRATE command results in six
response packets being sent to the host.
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
9.3.4.3
Calibration Data Encoded and
Stored in EEPROM
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.
System integrators may prefer to preload 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
Coordinates are 10-bit significant values, scaled to
16-bit and stored in a High (Hi) and Low (Lo) byte pair.
Upper Left (Node 1) Upper Right (Node 2) Lower Right (Node 3)
X
Lo
Y
Hi
Lo
X
Hi
Lo
Y
Hi
Lo
X
Hi
Lo
Lower Left (Node 4)
Y
Hi
Lo
X
Hi
Lo
Flip State
Y
Hi
Lo
Hi
Decode the above data to as follows:
1.
2.
3.
Swap the order of stored low and high bytes for
a given coordinate.
Convert the 16-bit value (stored high and low
bytes) from hexadecimal to decimal.
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
REGISTER 9-2:
FLIP STATE BYTE
U-0
U-0
U-0
U-0
U-0
R/W
R/W
R/W
—
—
—
—
—
XYFLIP
XFLIP
YFLIP
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
bit 7-3
Unimplemented: Read as ‘0’
bit 2
XYFLIP: X and Y Axis Flip bit
1 = X and Y axis are flipped
0 = X an Y axis are not flipped
bit 1
XFLIP: X-Axis Flip bit
1 = X-axis flipped
0 = X-axis not flipped
bit 0
YFLIP:Y-Axis Flip bit
1 = Y-axis flipped
0 = Y-axis not flipped
U = Unimplemented bit, read as ‘0’
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” and Section 10.2 “AR1011/AR1021 Storing Default Calibration Values to EEPROM”).
2009-2016 Microchip Technology Inc.
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
9.3.5
REGISTER_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:
1.
2.
3.
Issue the REGISTER_START_ADDRESS_REQUEST
command to obtain the Start address for the
register group.
Calculate the desired register’s absolute
address by adding the register’s Offset value to
Start address for the register group.
Issue this REGISTER_READ command, as
follows, using the calculated register’s absolute
address:
Send:
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.
Send:
Receive:
9.3.8
REGISTERS_WRITE_TO_EEPROM –
0x23
Register Address High byte: 0x00
Save Configuration register values to EEPROM. This
allows the controller to remember configurations
settings through controller power cycles.
# of Registers to Read:
Send:
0x01 thru 0x08
Receive: …
Receive:
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.
The controller has 256 bytes of on-board EEPROM.
9.3.6
REGISTER_WRITE – 0x21
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:
1.
2.
3.
Issue the REGISTER_START_ADDRESS_REQUEST
command to obtain the Start address for the
register group.
Calculate the desired register’s absolute
address by adding the register’s Offset value to
Start address for the register group.
Issue this REGISTER_WRITE command, as
follows, using the calculated register’s absolute
address:
Send:
…
9.3.9
EEPROM_READ – 0X28
• The first 128 bytes (address range 0x00-0x7F)
are reserved by the controller for the
Configuration register settings and calibration
data.
• The second 128 bytes (address range
0x80-0xFF) are provided for the user’s
application, if desired.
This command provides a means to read values from
the EEPROM.
Send:
Register Address High byte: 0x00
# of Registers to Read: 0x01 thru 0x08
Receive:
…
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.
to
Register Address High byte: 0x00
# of Registers to Read:
0x01 thru 0x08
Receive:
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
9.3.10
EEPROM_WRITE – 0x29
9.3.12
The controller has 256 bytes of on-board EEPROM.
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.
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 Address
Function
Warning: ONLY write to user EEPROM addresses of
0x80-0xFF.
0x00
0x01
One of the following actions is required for
EEPROM changes to be used by the
controller:
0x02
0x03
Touch Threshold
• The controller power must be cycled
from OFF to ON or
• Issue the EEPROM_WRITE_TO_REGISTERS command.
0x04
Sensitivity Filter
0x05
Sampling Fast
0x06
Sampling Slow
0x07
Accuracy Filter Fast
Write to EEPROM as follows:
0x08
Accuracy Filter Slow
Send:
0x09
Speed Threshold
0x0A
0x0B
Sleep Delay
0x0C
Pen-Up Delay
0x0D
Touch Mode
…
to
Register Address High byte: 0x00
0x0E
Touch Options
# of Registers to Read: 0x01 thru 0x08
0x0F
Calibration Inset
Receive:
0x10
Pen State Report Delay
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.
0x11
0x12
Touch Report Delay
0x13
0x14
Data Block Separator
0x15
Calibration UL X-low
0x16
Calibration UL X-high
0x17
Calibration UL Y-low
0x18
Calibration UL Y-high
0x19
Calibration UR X-low
0x1A
Calibration UR X-high
0x1B
Calibration UR Y-low
0x1C
Calibration UR Y-high
0x1D
Calibration LR X-low
0x1E
Calibration LR X-high
0x1F
Calibration LR Y-low
9.3.11
EEPROM_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:
Receive:
2009-2016 Microchip Technology Inc.
DS40001393C-page 37
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
TABLE 9-6:
AR1010/AR1020 EEPROM
AND REGISTER MAP
TABLE 9-7:
AR1011/AR1021 EEPROM
AND REGISTER MAP
EEPROM Address
Function
EEPROM Address
Function
0x20
Calibration LR Y-high
0x1D
Calibration UR Y-low
0x21
Calibration LL X-low
0x1E
Calibration UR Y-high
0x22
Calibration LL X-high
0x1F
Calibration LR X-low
0x23
Calibration LL Y-low
0x20
Calibration LR X-high
0x24
Calibration LL Y-high
0x21
Calibration LR Y-low
0x25
Calibration Flip State
0x22
Calibration LR Y-high
0x26:0x7E
0x23
Calibration LL X-low
0x7F
End of Controller Space
0x24
Calibration LL X-high
0x80:0xFF
User Space
0x25
Calibration LL Y-low
0x26
Calibration LL Y-high
0x27
Calibration Flip State
TABLE 9-7:
AR1011/AR1021 EEPROM
AND REGISTER MAP
0x28
Calibration – Checksum
0x29:0x50
Not used
0x51:0x7F
0x01
Configuration Registers –
Block Key
0x80:0xFF
User Space
0x02
EEPROM Address
Function
0x00
0x03
0x04
Touch Threshold
0x05
Sensitivity Filter
0x06
Sampling Fast
0x07
Sampling Slow
0x08
Accuracy Filter Fast
0x09
Accuracy Filter Slow
0x0A
Speed Threshold
0x0B
0x0C
Sleep Delay
0x0D
Pen-Up Delay
0x0E
Touch Mode
0x0F
Touch Options
0x10
Calibration Inset
0x11
Pen State Report Delay
0x12
0x13
Touch Report Delay
0x14
0x15
Configuration Registers –
Checksum
0x16
Calibration - Block Key
0x17
Calibration UL X-low
0x18
Calibration UL X-high
0x19
Calibration UL Y-low
0x1A
Calibration UL Y-high
0x1B
Calibration UR X-low
0x1C
Calibration UR X-high
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
10.0
APPLICATION NOTES
5.
10.1
Calibration of Touch Sensor with
Controller
Send:
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.
Set the Calibration Inset by writing the desired
value to the CalibrationInset register.
Receive:
6.
Issue the CALIBRATE_MODE command.
Send:
Receive:
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:
The calibration process can be canceled 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.
Touch and
The process of “calibration” with the controller is
described below.
1.
Release Target
Disable touch reporting by issuing command.
Send:
8.
Receive:
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:
9.
Wait for the user to touch and release the first
calibration point target. Do this by looking for a
controller response of:
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.
Receive:
3.
SUGGESTED TEXT FOR
FIRST CALIBRATION
TARGET
Calculate the CalibrationInset register’s address
by adding its offset value of 0x0E to the register
group Start address of 0x20.
FIGURE 10-2:
SUGGESTED TEXT FOR
SECOND CALIBRATION
TARGET
Register Address = Register Start Address +
CalibratioInset Register Offset = 0x20 + 0x0E = 0x2E
Touch and
4.
Release Target
Calculate the desired
CalibrationInset register.
value
for
the
A Calibration Inset of 12.5% is used below for this
example.
CalibrationInset = 2 * Desire Calibration Inset % = 2 *
12.5 = 25 = 0x19
2009-2016 Microchip Technology Inc.
10. Wait for the user to touch and release the
second calibration point target. Do this by
looking for a controller response of:
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
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
Touch and
Release Target
14. Wait for the user to touch and release the fourth
calibration point target. Do this by looking for a
controller response of:
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
16. Enable
touch
reporting
by
issuing
ENABLE_TOUCH command.
Send:
Receive:
12. Wait for the user to touch and release the third
calibration point target. Do this by looking for a
controller response of:
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
Touch and
Release Target
DS40001393C-page 40
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
10.2
An example of calculating the checksum is shown
below (See Table 10-1).
AR1011/AR1021 Storing Default
Calibration Values to EEPROM
If you wish to implement fixed calibration values,
preloaded into the AR1000 EEPROM, then the
following procedure must be followed (See
Section 10.2.1 “Preparation for Fixed Calibration
Values”).
10.2.1
PREPARATION 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
Description
Value
Operation
Checksum Result
Seed
0x45
n/a
0x45
Block Key
0x55
0x45 + 0x55 =
0x9A
Upper Left
X
Low byte
0x06
0x9A + 0x06 =
0xA0
Upper Left
X
High byte
0x1B
0xA0 + 0x1B =
0xBB
Upper Left
Y
Low byte
0xA5
0xBB + 0xA5 =
0x60
Upper Left
Y
High byte
0x08
0x60 + 0x08 =
0x68
Upper Right
X
Low byte
0x13
0x68 + 0x13 =
0x7B
Upper Right
X
High byte
0xDF
0x7B + 0xDF =
0x5A
Upper Right
Y
Low byte
0xF4
0x5A + 0xF4 =
0x4E
Upper Right
Y
High byte
0x0B
0x4E + 0x0B =
0x59
Lower Right
X
Low byte
0x98
0x59 + 0x98 =
0xF1
Lower Right
X
High byte
0xE4
0xF1 + 0xE4 =
0xD5
Lower Right
Y
Low byte
0x1E
0xD5 + 0x1E =
0xF3
Lower Right
Y
High byte
0xEC
0xF3 + 0xEC =
0xDF
Lower Left
X
Low byte
0xBF
0xDF + 0xBF =
0x9E
Lower Left
X
High byte
0x1A
0x9E + 0x1A =
0xB8
Lower Left
Y
Low byte
0x32
0xB8 + 0x32 =
0xEA
Lower Left
Y
High byte
0xE7
0xEA + 0xE7 =
0xD1
0x01
0xD1 + 0x01 =
Flip State
Checksum
0xD2
0xD2
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
Checksum += Calibration value
Next Calibration value
2009-2016 Microchip Technology Inc.
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AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
10.2.2
EXECUTION OF FIXED
CALIBRATION VALUE LOADING
Follow error checking practices by checking the
AR1000 responses to issued commands.
1.
2.
3.
4.
Send the AR1000 DISABLE_TOUCH command.
Use the AR1000 EEPROM_WRITE command
multiple times to write the following to the
AR1000 EEPROM.
a. Block Key 0x55 to address 0x16
b. Data set to addresses 0x17:0x27. See
Section 9.3.4.3 “Calibration Data
Encoded and Stored in EEPROM” and
Section 9.3.12 “EEPROM Map”.
c. Checksum for the data block to address
0x28
d. Mirror image of a, b and c from above to
address 0x3E:0x50
Set the CCE bit of the TouchOptions register.
This will enable the controller to use the
calibration data on the next power boot. See
Section 10.2.3 “Configuring the CCE bit to
Use Fixed Calibration Values” for additional
details on the CCE bit.
Send the AR1000 ENABLE_TOUCH (0x12)
command.
10.2.3
CONFIGURING THE CCE BIT TO
USE FIXED CALIBRATION VALUES
The CCE bit of the TouchOptions Register (offset
0x0D) must be set to ‘1’ to enable the usage of the
stored calibration values in EEPROM.
This should be completed before re-enabling the
controller via the ENABLE_TOUCH command.
REGISTER 10-1:
CCE BIT FORMAT
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
DS40001393C-page 42
2009-2016 Microchip Technology Inc.
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
1.
2.
3.
4.
5.
Send the DISABLE_TOUCH (0x13) command.
Send the
REGISTER_START_ADDRESS_REQUEST
(0x22) to determine the absolute address for
TouchOptions Register.
Send the REGISTER_WRITE (0x21) command
to set the CCE bit of the TouchOptions Register.
Send REGISTERS_WRITE_TO_EEPROM (0x23)
command to have all current registers stored
into EEPROM.
Send the AR1000 ENABLE_TOUCH (0x12)
command.
The controller will use the stored calibration data after
cycling power to the controller.
10.2.4
EEPROM_WRITE COMMAND TO
STORE DEFAULT CALIBRATION
The EEPROM_WRITE command is shown in this
section. See Section 9.0 “Commands” for more
command details.
10.2.5
QUALITY 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.
10.2.6
EXAMPLE 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:
ULxL = Upper Left corner x-coordinate Low byte
:
LLyH = Lower Left corner y-coordinate High byte
DISABLE_TOUCH
= application specific value
Send to AR1000:
0x55
Header
0x
Number of bytes to follow this one
0x29
Command ID
0x00
Desired 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
Response from AR1000:
0x55
Header
0x02
Number of bytes to follow this one
0x00
Success response
0x29
Command ID
2009-2016 Microchip Technology Inc.
DS40001393C-page 43
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
Disable Touch
Command:
55
01
13
Response:
55
02
00
13
Write Calibration to EEPROM Image # 1
Command:
55
0C
29
00
Response:
55
02
00
29
Command:
55
0C
29
00
Response:
55
02
00
29
Command:
55
07
29
00
Response:
55
02
00
29
16
08
55
ULxL
ULxH
ULyL ULyH URxL URxH URyL
1E
08
URyH
LRxL
LRxH
LRyL LRyH LLxL
26
03
LLyH
FlipS
Chksm
3E
08
55
ULxL
ULxH
ULyL ULyH URxL URxH URyL
46
08
URyH
LRxL
LRxH
LRyL LRyH LLxL
4E
03
LLyH
FlipS
Chksm
LLxH
LLyL
Write Calibration to EEPROM Image # 2
Command:
55
0C
29
00
Response:
55
02
00
29
Command:
55
0C
29
00
Response:
55
02
00
29
Command:
55
07
29
00
Response:
55
02
00
29
LLxH
LLyL
Enable Use of Calibrated Data
Command:
55
01
22
Response:
55
03
00
22
Command:
4/8-Wire
55
05
21
00
01
01
5-Wire
55
05
21
00
01
03
Response:
55
02
00
21
Command:
55
01
12
Response:
55
02
00
Enable Touch
DS40001393C-page 44
12
2009-2016 Microchip Technology Inc.
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
11.0
ELECTRICAL SPECIFICATIONS
Absolute Maximum Ratings(†)
Ambient temperature under bias....................................................................................................... -40°C to +125°C
Storage temperature ........................................................................................................................ -65°C to +150°C
Voltage on VDD with respect to VSS .................................................................................................... -0.3V to +6.5V
Voltage on all other pins with respect to VSS ........................................................................... -0.3V to (VDD + 0.3V)
Total power dissipation................................................................................................................................... 800 mW
Maximum current out of VSS pin .................................................................................................................... 300 mA
Maximum current into VDD pin ....................................................................................................................... 250 mA
Input clamp current (VI < 0 or VI > VDD) 20 mA
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.
2009-2016 Microchip Technology Inc.
DS40001393C-page 45
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
11.1
Minimum Operating Voltage
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.
11.2
AR1000 Electrical Characteristics
Operating Voltage: 2.5 ≤ VDD ≤ 5.25V
Function
Pin
Input
M1
M1
VSS ≤ VIL ≤ 0.15*VDD
(0.25*VDD + 0.9V) ≤ VIH ≤ VDD
—
M2
M2
VSS ≤ VIL ≤ 0.15*VDD
(0.25*VDD + 0.9V) ≤ VIH ≤ VDD
—
SCL/SCK
SCL/SCK/TX
VSS ≤ VIL ≤ 0.2*VDD
0.8*VDD ≤ VIH ≤ VDD
—
TX
SCL/SCK/TX
—
VSS ≤ VOL(1) ≤ (1.2V – 0.15*VDD)(2)
(1.25*VDD – 2.25V)(3) ≤ VOH(1) ≤ VDD
SDI
SDI/SDA/RX
VSS ≤ VIL ≤ 0.2*VDD
0.8*VDD ≤ VIH ≤ VDD
—
SDO
SDO
—
VSS ≤ VOL(1) ≤ (1.2V – 0.15*VDD)(2)
(1.25*VDD – 2.25V)(3) ≤ VOH(1) ≤ VDD
SIQ
SIQ
—
VSS ≤ VOL(1) ≤ (1.2V – 0.15*VDD)(2)
(1.25*VDD – 2.25V)(3) ≤ VOH(1) ≤ VDD
SDA
SDI/SDA/RX
VSS ≤ VIL ≤ 0.2*VDD
0.8*VDD ≤ VIH ≤ VDD
Open-drain
RX
SDI/SDA/RX
VSS ≤ VIL ≤ 0.2*VDD
0.8*VDD ≤ VIH ≤ VDD
—
SS
SS
VSS ≤ VIL ≤ 0.2*VDD
0.8*VDD ≤ VIH ≤ VDD
—
Note 1:
2:
3:
Output
These parameters are characterized but not tested.
At 10 mA.
At -4 mA.
DS40001393C-page 46
2009-2016 Microchip Technology Inc.
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
12.0
PACKAGING INFORMATION
12.1
Package Marking Information
20-Lead SSOP (5.30 mm)
Example
AR1021
I/SS e3
1042256
20-Lead SOIC (7.50 mm)
XXXXXXXXXXXX
XXXXXXXXXXXX
XXXXXXXXXXXX
YYWWNNN
Legend: XX...X
Y
YY
WW
NNN
e3
*
Note:
*
Example
AR1021
I/SO e3
1042256
Customer-specific information
Year code (last digit of calendar year)
Year code (last 2 digits of calendar year)
Week code (week of January 1 is week ‘01’)
Alphanumeric traceability code
Pb-free JEDEC designator for Matte Tin (Sn)
This package is Pb-free. The Pb-free JEDEC® designator e( 3 )
can be found on the outer packaging for this package.
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.
2009-2016 Microchip Technology Inc.
DS40001393C-page 47
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
12.2
Package Marking Information (Continued)
20-Lead QFN (4x4x0.9 mm)
PIN 1
PIN 1
Legend: XX...X
Y
YY
WW
NNN
e3
*
Note:
*
Example
AR1021
I/ML e3
1042256
Customer-specific information
Year code (last digit of calendar year)
Year code (last 2 digits of calendar year)
Week code (week of January 1 is week ‘01’)
Alphanumeric traceability code
Pb-free JEDEC designator for Matte Tin (Sn)
This package is Pb-free. The Pb-free JEDEC® designator e( 3 )
can be found on the outer packaging for this package.
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.
DS40001393C-page 48
2009-2016 Microchip Technology Inc.
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
12.3
Note:
Ordering
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
Communication
Type
Temp. Range
AR1011-I/ML
UART
AR1011-I/SO
UART
AR1011-I/SS
AR1011T-I/ML
Part Number
Pin Package
Packing
-40°C to + 85°C
QFN, 20 pin
Tube
-40°C to + 85°C
SOIC, 20 pin
Tube
UART
-40°C to + 85°C
SSOP, 20 pin
Tube
UART
-40°C to + 85°C
QFN, 20 pin
T/R
AR1011T-I/SO
UART
-40°C to + 85°C
SOIC, 20 pin
T/R
AR1011T-I/SS
UART
-40°C to + 85°C
SSOP, 20 pin
T/R
AR1021-I/ML
I2C/SPI
-40°C to + 85°C
QFN, 20 pin
Tube
AR1021-I/SO
I2C/SPI
-40°C to + 85°C
SOIC, 20 pin
Tube
AR1021-I/SS
I2C/SPI
-40°C to + 85°C
SSOP, 20 pin
Tube
AR1021T-I/ML
I2C/SPI
-40°C to + 85°C
QFN, 20 pin
T/R
AR1021T-I/SO
I
2C/SPI
-40°C to + 85°C
SOIC, 20 pin
T/R
AR1021T-I/SS
I2C/SPI
-40°C to + 85°C
SSOP, 20 pin
T/R
AR1010-I/ML
UART
-40°C to + 85°C
QFN, 20 pin
Tube
AR1010-I/SO
UART
-40°C to + 85°C
SOIC, 20 pin
Tube
AR1010-I/SS
UART
-40°C to + 85°C
SSOP, 20 pin
Tube
AR1010T-I/ML
UART
-40°C to + 85°C
QFN, 20 pin
T/R
AR1010T-I/SO
UART
-40°C to + 85°C
SOIC, 20 pin
T/R
AR1010T-I/SS
UART
-40°C to + 85°C
SSOP, 20 pin
T/R
AR1020-I/ML
I2C/SPI
-40°C to + 85°C
QFN, 20 pin
Tube
AR1020-I/SO
I2C/SPI
-40°C to + 85°C
SOIC, 20 pin
Tube
AR1020-I/SS
I2C/SPI
-40°C to + 85°C
SSOP, 20 pin
Tube
AR1020T-I/ML
I2C/SPI
-40°C to + 85°C
QFN, 20 pin
T/R
AR1020T-I/SO
2
I C/SPI
-40°C to + 85°C
SOIC, 20 pin
T/R
AR1020T-I/SS
I2
-40°C to + 85°C
SSOP, 20 pin
T/R
C/SPI
2009-2016 Microchip Technology Inc.
DS40001393C-page 49
AR1000 SERIES RESISTIVE TOUCH SCREEN CONTROLLER
12.4
Package Details
The following sections give the technical details of the packages.
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