Features
•
maXTouch
®
Touchscreen
– Two touchscreens with true 12-bit multiple touch reporting and real-time XY
tracking for up to 16 concurrent touches per touchscreen
– Screen sizes 8 – 12.1 inches diagonal supported at 5 mm electrode pitch.
Number of Channels
– Electrode grid configurations of up to 32 X and 52 Y lines supported
– Touchscreens up to 1664 channels (subject to other configurations)
– Up to 32 channels can be allocated as fixed keys (subject to other configurations)
Signal Processing
– Advanced digital filtering using both hardware engine and firmware
– Self-calibration
– Auto drift compensation
– Adjacent Key Suppression
®
(AKS
®
) technology
– Noise cancellation algorithms for display noise suppression
– Grip suppression and suppression of unintentional touches
– Down-scaling and clipping support to match LCD resolution
– Ultra-fast start-up and calibration for best user experience
– Supports axis flipping and axis switch-over for portrait and landscape modes
– Fast and powerful 32-bit processor core
– Supports baseline reference data for better calibration
– Supports lens bending algorithms to restore signal distortions
Scan Speed
– Maximum single touch >250Hz, subject to configuration
– Maximum 16 touches >100Hz, subject to configuration
– Configurable to allow power/speed optimization
– Programmable timeout for automatic transition from active to idle states
Response Times
– Initial latency <15 ms for first touch from idle, subject to configuration
Sensors
– Works with PET or glass sensors, including curved profiles
– Works with all proprietary sensor patterns recommended by Atmel
®
Stylus Support
– Supports passive stylus with 2 mm contact diameter, subject to configuration
– Supports Atmel maXStylus
™
, subject to configuration
Environmental Conditions
– Operating temperature –40°C to +85°C
– Moisture tolerance good
Panel Thickness
– Glass up to 2.5 mm, screen size dependent
– Plastic up to 1.2 mm, screen size dependent
Interfaces
– I
2
C-compatible slave mode; Standard/Fast Mode: up to 400 kHz, High speed mode:
up to 1.7 MHz
– USB 2.0-compliant composite device, full speed (12 Mbps)
– HID-I
2
C interface for Microsoft
®
Windows
®
8
•
•
maXTouch
®
1664-channel
Touchscreen
Controller
mXT1664S1
Revision 2.0
•
•
•
•
•
•
•
9871EX–AT42–12/13
•
Power
– Digital 1.8 V (I
2
C-compatible mode only) or 2.7 V to 3.3 V nominal
– Analog 2.7 V to 3.3V nominal
– High voltage X line drive 2.7 V to 10.0 V nominal
•
Packages
– 128-ball VFBGA 7 × 7 × 1 mm, 0.5 mm ball pitch
2
mXT1664S1
9871EX–AT42–12/13
mXT1664S1
1. Overview of the mXT1664S1
1.1
Introduction
The Atmel maXTouch family of touch controllers has set a new industry benchmark for
capacitive touchscreens with their low current consumption, fast response time and high levels
of accuracy. The mXT1664S1 single-chip solution offers the benefits of the maXTouch
enhanced architecture on devices with touchscreens up to 14 in. diagonal:
•
Patented capacitive sensing method
– The mXT1664S1 uses a unique charge-transfer
acquisition engine to implement the Atmel
-
patented QMatrix
®
capacitive sensing method.
This allows the measurement of up to 1664 mutual capacitance nodes. Coupled with a
state-of-the-art CPU, the entire touchscreen sensing solution can measure, classify and
track individual finger touches with a high degree of accuracy.
•
Capacitive Touch Engine (CTE)
– The mXT1664S1 features an acquisition engine, which
uses an optimal measurement approach to ensure almost complete immunity from
parasitic capacitance on the receiver inputs (Y lines). The engine includes sufficient
dynamic range to cope with anticipated touchscreen mutual capacitances, which allows
great flexibility for use with the Atmel proprietary ITO pattern designs. One and two layer
ITO sensors are possible using glass or PET substrates.
•
Noise filtering
– Hardware noise processing in the capacitive touch engine provides
enhanced autonomous filtering and allows a broad range of noise profiles to be handled.
The result is good performance in the presence of charger and LCD noise.
•
Processing power
– The main CPU has two powerful, yet low power, microsequencer
coprocessors under its control. These combine to allow the signal acquisition,
preprocessing, postprocessing and housekeeping to be partitioned in an efficient and
flexible way. This gives ample scope for sensing algorithms, touch tracking or advanced
shape-based filtering. An in-circuit reflash can be performed over the chip’s hardware-
driven interface.
•
Interpreting user intention
– The Atmel mutual capacitance method provides
unambiguous multitouch performance. Algorithms in the mXT1664S1 provide optimized
touchscreen position filtering for the smooth tracking of touches. Stylus support allows
stylus touches to be detected and distinguished from other touches, such as finger
touches. The suppression of unintentional touches from the user’s gripping fingers, resting
palm or touching cheek or ear also help ensure that the user’s intentions are correctly
interpreted.
1.2
Understanding Unfamiliar Concepts
If some of the concepts mentioned in this datasheet are unfamiliar, see the following sections
for more information:
•
Appendix C on page 81
for a glossary of terms
•
Appendix D on page 82
for QMatrix technology
3
9871EX–AT42–12/13
1.3
Resources
The following datasheet provide essential information on configuring the device:
•
mXT1664S 2v0 Protocol Guide
The following documents may also be useful (available by contacting Atmel’s Touch
Technology Division):
• Configuring the device:
– Application Note: QTAN0058 –
Rejecting Unintentional Touches with the
maXTouch Touchscreen Controllers
– Application Note: QTAN0078 –
maXTouch Stylus Tuning
• Miscellaneous:
– Application Note QTAN0050 –
Using the maXTouch Debug Port
– Application Note QTAN0061 –
maXTouch
™
Sensitivity Effects for Mobile Devices
– Application Note QTAN0086 –
Touchscreen Design for Gloved Operation
• Touchscreen design and PCB/FPCB layout guidelines:
– Application Note QTAN0054 –
Getting Started with maXTouch Touchscreen
Designs
– Application Note QTAN0094 –
mXT1664S PCB/FPCB Layout Guidelines
– Application Note QTAN0080 –
Touchscreens Sensor Design Guide
•
Other documents –
The device uses the same core technology as the mXT768E, so the
following documents may also be useful (available by contacting the Atmel Touch
Technology division):
– Application Note: QTAN0083 –
mXT768E Power and Speed Considerations
– Application Note QTAN0052 –
mXT224 Passive Stylus Support
4
mXT1664S1
9871EX–AT42–12/13
mXT1664S1
2. Pinout and Schematic
2.1
Pinout Configuration
N
X31
M
X28
L
X26
K
GND
J
X22
H
X20
G
X17
F
Y41
E
Y38
D
GND
C
AVDD
B
Y33
A
Y32
1
Y29
2
Y26
3
Y49
4
Y48
5
Y45
6
Y30
Y27
Y50
AVDD
Y46
Y31
Y28
Y51
GND
Y47
Y35
Y34
Y37
Y36
Y40
Y39
Y44
XVDD
X16
X25
X19
X18
X21
GND
X24
X23
XVDD
X27
VDD
X29
X30
GND
VDD
VDD
VDDUSB
GND
RESET
SDA
I2CMODE
X4
NC
X4
VDDCORE
GND
GPIO1
GPIO0
X15
X14
SCL
X4
XOUT
GND
Reserved CHRG_IN
X13
X12
USBDM VDD_INPUT
USBDP
DBG_CLK DBG_DATA
XIN
CHG
COMMSEL
X11
X10
XVDD
X9
X8
GND
X7
X4
X6
X5
SYNC(TDI) INDICATION ADDSEL
X4
X3
X2
GND
X4
X1
XVDD
X0
Y43
Y23
Y10
Y9
Y8
Y13
Y12
Y11
Y15
X4
AVDD
Y14
Y42
X4
Y20
Y18
Y16
Y5
GND
Y0
Y24
X4
Y21
GND
AVDD
Y6
Y3
Y1
Y25
7
Y22
8
Y19
9
Y17
10
Y7
11
Y4
12
Y2
13
Bottom View
5
9871EX–AT42–12/13
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