AN11622 LPC82x Touch Solution Quick Start Guide

AN11622
LPC82x Touch Solution Quick Start Guide
Rev. 1.0 — 22 December 2014
Application Note
Document information
Info
Content
Keywords
Capacitive Touch, Touchpad, Sensor, Electrode, Drive/Sensing lines,
Dielectric, Overlay panel, Sensitivity, Touch, False Touch.
Abstract
This application note describes the overall hardware design aspect of
NXP’s Capacitive Touch solution, shows the schematic design, materials,
and PCB design including the most critical Touch sensor design.
AN11622
NXP Semiconductors
LPC82x Touch Solution Quick Start Guide
Revision history
Rev
Date
1.0
20141222
Description
Initial version
Contact information
For more information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: salesaddresses@nxp.com
AN11622
Application Note
All information provided in this document is subject to legal disclaimers.
Rev. 1.0 — 22 December 2014
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LPC82x Touch Solution Quick Start Guide
1. Introduction
NXP’s Capacitive Touch solution is based on the innovative Switched Capacitor
Integration technology. This variant of the solution is centered around the LPC82x MCU
family. It consists of hardware and software platform for enabling the Touch user
interface designs. This quick start guide briefly outlines different elements involved in this
Touch solution and help in getting started with the set up.
Main Features:

LPC824 centric capacitive Touch

Modes supported
o
Touchpad (8-bit resolution)
o
9 Keys

GUI to visualize/analyze the Touch data

On-board LCD to display Touch positions

Arduino UNO compatible Touch Shield

Mbed/LPCXpresso and Pmod® options

USB Drag and drop programming

CMSIS-DAP debug interface

USB powered
The LPC82x Touch solution kit can be ordered from NXP’s authorized distributors using
the order number OM13081.
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2. Hardware Setup
The LPC82x Touch solution has been realized using two boards, LPCXpresso824-MAX
(LPC82x Xpresso v2/mbed) board and LPC82x Touch shield board.
2.1 LPCXpresso824-MAX (LPC82x Xpresso v2/mbed)
The LPCXpresso824-MAX is a standard Xpresso/mbed board with LPC824 on it, well
supported in the overall ecosystem. This board combines the overall features of the
LPCXpresso, mbed, and Arduino environments. See the LPCXpresso824-MAX board
user manual for more details:
http://www.nxp.com/documents/user_manual/UM10830.pdf







LPC824 in HVQFN33 package
On-board CMSIS-DAP debug interface
o Supports LPCXpresso IDE
o Supports mbed and other third party tools
Expansion options
o Arduino UNO R3-compatible connectors
o Mbed/LPCXpresso and Pmod® options
o Prototyping area
RGB LED for test/debug
10-pin SWD connector for external debug probe
UART ISP capable
USB powered
Debug – LPC11U35
Target - LPC824
Arduino Expansion
SW2-ISP
RGB LED
mbed/Xpresso
Expansion
PMOD
USB
Connector
Prototyping
area
Reset SW
mbed/Xpresso
Expansion
Arduino Expansion
External Debug
Fig 1.
LPCXpresso824 –MAX board
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LPC82x Touch Solution Quick Start Guide
2.2 LPC82x Touch Shield
The LPC82x Touch Shield is an add-on board with capacitive Touch sensors (3x3 Matrix
touchpad) and a character LCD to display the Touch position data.
LCD
Touch Sensors
(3x3 Matrix
touchpad)
Fig 2.
LPC82x Touch Shield
2.3 LPC82x Touch Setup
The LPCXpresso824-MAX board and LPC82x Touch shield are connected via Arduino
UNO expansion connectors.
+
Fig 3.
LPC82x Touch Setup
LPC82x Touch Shield
LPCXpresso824-MAX
=
LPC82x Touch Setup
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3. Software
3.1 Touch Firmware
The LPC82x Touch solution kit is pre-programmed with the Touch demo firmware and it
can be operated in standalone mode (without GUI) or with the windows GUI.
3.2 Touch GUI
The LPC82x Touch Solution provides a Windows based GUI to visualize and analyze the
Touch status/position data.
To use the Touch GUI, download and install the mbed windows serial port driver from:
www.nxp.com/redirect/mbed/handbook/Windows-serial-configuration
Touch
position
X field
Debug
Messages
Touch position
Touch
position
Drawing field
X-Y
Coordinates
Y field
Status Messages
Fig 4.
Touch GUI
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4. Getting Started
4.1 Programming and Setting it up
 Though the kit is pre-programmed with the touch demo firmware, one can always reprogram it very easily with the latest firmware available.
 Connect the LPCXpresso824-MAX board and LPC82x Touch Shield using Arduino
UNO expansion connectors. See Fig 3.
 On powering-up the kit with micro USB cable, it will appear as an MBED mass storage
device on the PC/Notebook.
 To program the kit with latest firmware, copy and paste or drag and drop the latest
binary to this MBED mass storage device.
 Power cycle or reset the board using reset switch (SW3) to get started.
4.2 Standalone Demo (without GUI)
The standalone demo works in two different modes, Two dimensional Mode
(Touchpad) and One dimensional Mode (Keys/Button).
 By default, the kit powers up in two dimensional Mode (position data).
 LCD will display “NXP””Firmware Version””Touch” in a sequence.
 And “Touch” display would remain until the touchpad is touched, as shown in Fig 5.
 Touching the touchpad area, the LCD will display X-Y coordinates of the Touch
position. The actual Touch position is reported in an 8-bit resolution (0 to 255) but it is
divided by a factor of 4 just to display on the LCD (00 to 63).
 Touch status is indicated by a segment right to the Y-coordinate, and it stays on as
long as the finger ouches the touchpad.
X- Coordinate
Y- Coordinate
Touch Status
Fig 5.
Standalone Demo (Touchpad Mode)
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 One can switch to the One dimensional Mode (Keys/Button) by pressing SW2 (ISP)
switch, see Fig 1 on the LPCXpresso824-MAX board.
 Change of mode is indicated by displaying “--1D--” which stays until the touchpad is
touched, as shown in Fig 6.
 On touching the sensor/sensors, the LCD will display hexadecimal (16 bit) value of the
respective sensor/sensors status (bit0:sensor0, bit1:sensor1).
 Touch status is indicated by a segment right to the Y-coordinate and stays on as long
as the finger touches the touchpad.
S1 Touched
Fig 6.
Touch Status
Standalone Demo (Key Mode)
 Press SW2 (ISP) switch to switch back to the Two dimensional Mode (Touchpad).
 Change of mode is indicated on the LCD by displaying “--2D--” which stays until the
touchpad is touched.
 Now the touchpad starts reporting X-Y coordinates of the touchpad.
4.3 Touch GUI Demo
Touch GUI provides many more features to visualize, test, and validate the LPC82x
Touch Solution.
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Powering-up the LPCXpresso824-MAX board using Micro USB cable, the USB port
should be recognized as a “mbed Serial Port” by PC/Notebook. If not, download and
install the mbed windows serial port driver from:
www.nxp.com/redirect/mbed/handbook/Windows-serial-configuration
 Launch the LPC82x Touch solution GUI, see Fig 7.
 Select proper COM port (check the device manager to make sure, if needed).
 Set the baud rate as 9600 and Open the Com port.
 Analysis window will display the communication errors, if there’s any problem with the
COM port or Baud rate selection.
 Successful Com port opening is indicated by a small radio button (next to Baud rate)
turning “Green” from “Red”.
 By default, the kit starts up in Two dimensional mode (Touch Position Mode).
Com Port status
Fig 7.
Connect to Com port
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 On touching the touchpad the Touch positions get reflected in the “Drawing field” of
the GUI. See Fig 8.
 One can draw any pattern or the character and the Touch position is indicated
accordingly.
 X and Y fields to the right show the X and Y touch field movements separately.
 Serial Messages window displays the Touch data packets with their IDs (ID:X:Y ) as
being received by the GUI, limited to first 192 Touch positions only.
 One can tick/un-tick the “Debug Enable” to enable/disable the display of touch data
packets (ID:X:Y ) in Serial Messages window.
Fig 8.
Visualize Touch Data
 Click on “Parameter settings” shown in Fig 9 to see and alter the Touch configuration
parameters. Default parameters set is shown on the entry.
 One can read the parameters from target hardware or write the altered parameters to
the target hardware using the radio buttons in the Target section.
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 One can also save the current parameters to the host or load the pre-set set of
parameters from the host to write to the target. See radio buttons in the Host section.
 While changing the parameters (value) settings, the range shown on the right is the
guideline. Even if out of range values are set, it will be truncated to the maximum
value.

One can always fall back and load the default set of parameters to cross verify the
settings at any time.
Host
Target
Fig 9.
Touch Parameter Handling
 See the “LPC82x Touch Solution Application Note” or “LPC82x Touch Solution Library
User Guide” for more details on all of the Touch configuration parameters.
 One can change the mode to One dimensional mode (Keys/Button Mode) by
selecting “One dimensional” in the drop down for Touch operating mode. See
Fig 10.
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 After changing the mode, click on “Write parameters to target” and the status window
displays: “Parameters successfully written to target”. The on board LCD also displays
PARAM.
Fig 10. Switching to One Dimensional Mode
 Close the Touch Parameter Handling window after the altered parameters are
successfully written to the target.
 The individual Sensor (S1-S9) status can be seen in the Drawing field. See Fig 11.
 On touching any sensor on the board, the corresponding change (√) is reflected in the
sensor status of that sensor. The on board LCD also displays the hexadecimal (16 bit)
value representing each sensor status.
 The (√) disappears or the respective sensor status is updated as soon as the finger is
removed from the sensor.
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Fig 11. One Dimensional Mode
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5. Legal information
5.1 Definitions
Draft — The document is a draft version only. The content is still under
internal review and subject to formal approval, which may result in
modifications or additions. NXP Semiconductors does not give any
representations or warranties as to the accuracy or completeness of
information included herein and shall have no liability for the consequences
of use of such information.
5.2 Disclaimers
Limited warranty and liability — Information in this document is believed to
be accurate and reliable. However, NXP Semiconductors does not give any
representations or warranties, expressed or implied, as to the accuracy or
completeness of such information and shall have no liability for the
consequences of use of such information.
In no event shall NXP Semiconductors be liable for any indirect, incidental,
punitive, special or consequential damages (including - without limitation lost profits, lost savings, business interruption, costs related to the removal
or replacement of any products or rework charges) whether or not such
damages are based on tort (including negligence), warranty, breach of
contract or any other legal theory.
Notwithstanding any damages that customer might incur for any reason
whatsoever, NXP Semiconductors’ aggregate and cumulative liability
towards customer for the products described herein shall be limited in
accordance with the Terms and conditions of commercial sale of NXP
Semiconductors.
Right to make changes — NXP Semiconductors reserves the right to make
changes to information published in this document, including without
limitation specifications and product descriptions, at any time and without
notice. This document supersedes and replaces all information supplied prior
to the publication hereof.
Suitability for use — NXP Semiconductors products are not designed,
authorized or warranted to be suitable for use in life support, life-critical or
safety-critical systems or equipment, nor in applications where failure or
malfunction of an NXP Semiconductors product can reasonably be expected
to result in personal injury, death or severe property or environmental
damage. NXP Semiconductors accepts no liability for inclusion and/or use of
NXP Semiconductors products in such equipment or applications and
therefore such inclusion and/or use is at the customer’s own risk.
Applications — Applications that are described herein for any of these
products are for illustrative purposes only. NXP Semiconductors makes no
representation or warranty that such applications will be suitable for the
specified use without further testing or modification.
Customers are responsible for the design and operation of their applications
and products using NXP Semiconductors products, and NXP
Semiconductors accepts no liability for any assistance with applications or
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customer product design. It is customer’s sole responsibility to determine
whether the NXP Semiconductors product is suitable and fit for the
customer’s applications and products planned, as well as for the planned
application and use of customer’s third party customer(s). Customers should
provide appropriate design and operating safeguards to minimize the risks
associated with their applications and products.
NXP Semiconductors does not accept any liability related to any default,
damage, costs or problem which is based on any weakness or default in the
customer’s applications or products, or the application or use by customer’s
third party customer(s). Customer is responsible for doing all necessary
testing for the customer’s applications and products using NXP
Semiconductors products in order to avoid a default of the applications and
the products or of the application or use by customer’s third party
customer(s). NXP does not accept any liability in this respect.
Export control — This document as well as the item(s) described herein
may be subject to export control regulations. Export might require a prior
authorization from competent authorities.
Evaluation products — This product is provided on an “as is” and “with all
faults” basis for evaluation purposes only. NXP Semiconductors, its affiliates
and their suppliers expressly disclaim all warranties, whether express,
implied or statutory, including but not limited to the implied warranties of noninfringement, merchantability and fitness for a particular purpose. The entire
risk as to the quality, or arising out of the use or performance, of this product
remains with customer.
In no event shall NXP Semiconductors, its affiliates or their suppliers be
liable to customer for any special, indirect, consequential, punitive or
incidental damages (including without limitation damages for loss of
business, business interruption, loss of use, loss of data or information, and
the like) arising out the use of or inability to use the product, whether or not
based on tort (including negligence), strict liability, breach of contract, breach
of warranty or any other theory, even if advised of the possibility of such
damages.
Notwithstanding any damages that customer might incur for any reason
whatsoever (including without limitation, all damages referenced above and
all direct or general damages), the entire liability of NXP Semiconductors, its
affiliates and their suppliers and customer’s exclusive remedy for all of the
foregoing shall be limited to actual damages incurred by customer based on
reasonable reliance up to the greater of the amount actually paid by
customer for the product or five dollars (US$5.00). The foregoing limitations,
exclusions and disclaimers shall apply to the maximum extent permitted by
applicable law, even if any remedy fails of its essential purpose.
5.3 Trademarks
Notice: All referenced brands, product names, service names and
trademarks are property of their respective owners.
All information provided in this document is subject to legal disclaimers.
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6. Contents
1.
2.
2.1
2.2
2.3
3.
3.1
3.2
4.
4.1
4.2
4.3
5.
5.1
5.2
5.3
6.
Introduction ......................................................... 3
Hardware Setup ................................................... 4
LPCXpresso824-MAX (LPC82x Xpresso
v2/mbed) ............................................................ 4
LPC82x Touch Shield ........................................ 5
LPC82x Touch Setup ......................................... 5
Software ............................................................... 6
Touch Firmware ................................................. 6
Touch GUI .......................................................... 6
Getting Started .................................................... 7
Programming and Setting it up ........................... 7
Standalone Demo (without GUI) ........................ 7
Touch GUI Demo ............................................... 8
Legal information .............................................. 14
Definitions ........................................................ 14
Disclaimers....................................................... 14
Trademarks ...................................................... 14
Contents ............................................................. 15
Please be aware that important notices concerning this document and the product(s)
described herein, have been included in the section 'Legal information'.
© NXP B.V. 2014.
All rights reserved.
For more information, visit: http://www.nxp.com
For sales office addresses, please send an email to: salesaddresses@nxp.com
Date of release: 22 December 2014
Document identifier: AN11622