Interlink Electronics
®
FSR
VersaPad® USB Integration Guide
Document Part Number EIG-10001 Rev. A
Interlink Electronics and the six dot logo are registered trademarks of Interlink Electronics, Inc.
Force Sensing Resistors®
USB VersaPad®
Integration Guide
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USB VersaPad®
Integration Guide
Table of Contents
1.0 Introduction ...................................................................................................................... 1
2.0 Scope .................................................................................................................................. 1
3.0 Theory of Operation ....................................................................................................... 2
4.0 Features and Operation ............................................................................................... 4
4.1 USB .................................................................................................................................... 4
4.2 Software Driver ................................................................................................................... 4
4.3 Touchpad and Mouse ......................................................................................................... 4
4.4 VersaPad Features ............................................................................................................ 4
5.0 Mounting ............................................................................................................................ 6
5.1 Mounting and Capture Guidelines ...................................................................................... 7
5.2 Bottom Side Mounting ...................................................................................................... 10
5.3 Top Side Mounting ........................................................................................................... 10
5.4 PCB Keep Out Area ......................................................................................................... 11
6.0 Connection ..................................................................................................................... 12
6.1 Molex Headers ................................................................................................................. 12
6.2 Molex Header Cables ....................................................................................................... 12
6.3 Flat Flex Cable Connector (FFC) ..................................................................................... 12
6.4 Flex Cable ........................................................................................................................ 12
6.5 Molex Connector Pin-out .................................................................................................. 13
6.6 FFC Connector Pin-out..................................................................................................... 14
6.7 Cable Options ................................................................................................................... 15
7.0 USB Information ........................................................................................................... 16
7.1 Device PID and VID ......................................................................................................... 16
7.2 Data Packet ...................................................................................................................... 16
7.3 USB Suspend Mode ......................................................................................................... 16
7.4 Operating Voltage and Current ......................................................................................... 16
8.0 Drawings and Dimensions ......................................................................................... 17
9.0 Orderable Part Numbers ............................................................................................ 19
10.0 Intellectual Property & Other Legal Matters ...................................................... 19
11.0 Contact Interlink Electronics ................................................................................... 20
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USB VersaPad®
Integration Guide
1.0 Introduction
VersaPad is a versatile touchpad module indented for integration by OEMs into laptops, military
and rugged computers, panel PCs, and medical devices. With smoothness and sensitivity
internally enhanced by true pressure measurement, it offers all customary mouse functions-mousing, tapping, dragging, and scrolling. The module's tough, moisture and grime resistant
surface can be used with a finger or stylus, even in wet or dirty environments. Plus, it operates
over an extended temperature range of -20ºC to +60ºC.
2.0 Scope
This Integration Guide provides the OEM integrator with all of the necessary technical
information to successfully integrate VersaPad
Industrial Computers
Rugged /Militar y Notebook Co mpu ters
Desktop Keyboards
Handheld PCs
This USB VersaPad guide is relevant to two products:
USB VersaPad Module with Flat Flexible Cable Connectors (FFC)
USB VersaPad Module with Mole x 8-p in boa rd to wir e header con necto r
Part numbers and kit contents are detailed in section 9.
™
into products such as:
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USB VersaPad®
Integration Guide
3.0 Theory of Operation
The touchpad sensor is a four-wire resistive type. The pad is composed of two resistive layers
separated by an air gap. One plate is used for the X-axis and the other is used for the Y-axis.
When pressure is applied, the two resistive plates make contact. A micr ocon troller measures
position and pressure then uses advanced, proprietary algorithms to yield smooth mouse
functionality. Figure 1 shows the electrical representation of the sensor and Figure 2 shows a
simplified exploded view of the sensor.
Figure 1: VersaPad Equivalent Electrical Circuit
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Figure 2: Simplified Exploded View VersaPad Sensor
USB VersaPad®
Integration Guide
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USB VersaPad®
Integration Guide
4.0 Features and Operation
The detailed features of VersaPad are given below.
4.1 USB
The module is fully USB 2.0 compliant and enumerates utilizing native O/S drivers as a HID
mouse with Left, Right, and Center-Click capability. The mouse can also be suspended by
the host, but the mouse cannot wake the host from suspend mode. No features of the
mouse are settable by the host via USB.
4.2 Software Driver
The USB VersaPad enumerates as a standard three-button HID-comp lian t mouse and
requires no additional driver. In the futur e, Inter link may pro vide a driver th at adds
additional functionality and customization poss ib ilities to the Windows standard mouse
behavior.
4.3 Touchpad and Mouse
The module is a resistive, 4-wire X-Y touchpad measured by a microcontroller. When not
touched, the touchpad appears to the microcontroller as an open switch . On a touch event,
the processor detects this 'switch closure' and begins to evaluate the touchpad through a
series of measurements. The processor ' o vers amples' the touchpad to facilitate filtering
and processing of the mouse report.
4.4 VersaPad Features
4.4.1 Tap for Left-Click
A single tap gesture will be interpreted as a mouse left click at the position of the
cursor. Tap for left-click is enabled by default on the base design. Custom versions
can have tap features disabled.
4.4.2 Double Tap
A double tap gesture will be interpreted as a double mouse left click at the position of
the cursor. Double-tap is enabled by default on the base design. Custom versions can
have tap features disabled.
4.4.3 Tap and Drag
Double-tapping and maintaining contact w ith the touch pad on the sec ond tap in itia tes
tap (left-click) and drag. Tap-and-drag is enabled by default on the base design.
Custom versions can have tap features disabled .
4.4.4 Drag Edge Lock
If a Tap and Drag is released near any edge o f the touchp ad, th e dr ag wi ll no t be
released for three seconds. This allows the drag to be resu med with out requ ir ing
another double-tap. Drag edge lock is enabled by default on the b ase design. Custom
versions can have drag edge lock disabled.
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USB VersaPad®
Integration Guide
4.4.5 Drag Edge Lock Use Entire Pad
If a Tap and Drag is released anywhere on the touch pad, the drag w ill no t be rele ased
for three seconds. This allows the drag to be resumed without requiring another
double-tap. Drag edge lock use entire pad is disabled by default on the base design
and set to edge only. Custom vers ions can have drag edge lock use entire pad
enabled.
4.4.6 Right-Click in Upper Right Corner
Tapping the touchpad in its upper right corner is in terpre ted as a righ t-click . Corner
Right-Click is enabled by defaul t on the base design. Custom versions can ha ve this
feature disabled.
4.4.7 Right Edge Border Scrolling
Initiating a touch on the right border edge of the touchpad will set the mouse into
scrolling mode. The finger or stylus can then be moved up and down along the righ t
edge to scroll. This feature does not activate when the border region is entered dur ing
a mouse cursor movement gesture and the border region is used for mousing only.
Right edge border scrolling is enabled by default on the base design. Custom versions
can have this feature disabled.
4.4.8 External Buttons
External Right, Left, and Center-Click button are available via 4-pin FFC (J3) or Molex
header connector (J7).
4.4.9 Customization
Interlink Electronics prides itself on its ability to adapt to our customers’ needs .
For appropriate opportunities a custo miza ble list inclu des the follow ing :
Color and Texture of Graphic Layer
Multicolor graphic artwork, text, and logos
Orientation
Removal of features
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USB VersaPad®
Integration Guide
5.0 Mounting
A general bezel mounting method as shown in figure 3 is one p ossib le way to mount the
VersaPad Module. Mechanical installation of the VersaPad module has many critical features
that must be considered for mounting. In par ticu lar , care shou ld be taken to avoid in adve r tent
pressure on the top membrane of the sensor as such pressure co uld be confused with a user’s
external touch. The membrane is supported at its edge by an in ternal spacer, shown in figure 4
as the dashed line. Parts us ed to capture the VersaPad module must not make contact with the
sensor inside the electrically active area. A ge neral 3D CAD model of In terlink’s sugges ted
mounting method and geometry can be found on our website at
www.interlinkelectronics.com/Support
.
Figure 3: VersaPad Module Bezel Mounting Concept
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USB VersaPad®
Integration Guide
Figure 4: Top View of VersaPad sensor showing hidden spacer geometry.
Dimensions are in mm.
5.1 Mounting and Capture Guidelines
Achieving an optimal mounting design requires that consideration be given to the following
guidelines:
5.1.1 Capture
Design of the enclosure used to capture the VersaPad module can follow either a top
or bottom installation method. Pressure sensitive gaskets or adhesives ma y be used to
support and protect the VersaPad. Tolerances of gask ets, bezels, etc. should be
chosen to avoid contact with the sensor active area under all conditions.
5.1.2 Protection of the Spacer edge
It is possible that long term wear c an emboss the touchpad sensor near the spacer
edge. To avoid this, the top case or an add ition al bezel should be us ed to overh ang the
spacer. A small vertical gap is necessary to avoid touching the senso r. Size and
position tolerance should be chos en to overlap the spacer under a ll conditions. See
figure 5.
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USB VersaPad®
Integration Guide
5.1.3 Contamination
Moisture and debris contamination can jeopardiz e the per formance of the Ve rsaPad .
Hence, in instances where these factors are considerable, the designer may choose a
gasket strategy to avoid ingress.
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USB VersaPad®
Integration Guide
5.1.4 PCB Support
The clamping parts used to secure the PCB component side of the VersaPad module
should provide additional support wherever it is allowable.
5.1.5 Enclosure Material
Bezels and encasements can be made of c onduc tive or non-co nd uctive materia ls.
Proper care should be taken to avoid creating ESD concerns
5.1.6 Critical Capture Dimensions
The figure below shows the critical dimensions in positioning of the bezel or top case,
gasket, VersaPad, and enclosure. These recommendations are chosen to prevent
embossing near the spacer and to prevent inadvertent pressure on the top surface of
the sensor. All dimensions and tolerances apply to both top and bo ttom moun ting
methods.
Figure 5: Critical capture dimensions. Drawing is not to scale.
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USB VersaPad®
Integration Guide
5.2 Bottom Side Mounting
In bottom side integration, the mo dule is held up against an inner lip using a combination of
adhesive from above and pressure from beneath. The gaske t can both aid in assembly and
provide sealing. Support from beneath could be from a rear bezel, from case features such
as ribs or posts, or from other nearby components.
Figure 6: Side view of bottom side mounting. Drawing is not to scale
5.3 Top Side Mounting
In top side installation the module is set into a hole from above and then surrounded by a
bezel. The bezel could be secured with plastic snaps and/or adhesive gasketing. The bezel
need not be just a frame around the VersaPad, but could extend to be a larger piece of the
top case with a cutout.
Figure 7: Side view of top side mounting. Drawing is not to scale
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USB VersaPad®
Integration Guide
5.4 PCB Keep Out Area
The illustration below highlights the recommended keep out area for the mounting bracket or
other surrounding interfaces . The keep out area can be reduced as long as proper care and
tolerance studies are performe d to av oid in terference with components and interfacing
connectors. Also note that th e interfacing geometry should be designed to avoid
interference with the sensor tail that wraps around the PCBA. Maximum component heights
can be found in the drawing in section 8. The 3D CAD model on our webs ite is a use ful to ol
for packaging the VersaPad into your application.
Figure 8: Mounting Bracket & Keep out Area. Drawing is not to scale
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USB VersaPad®
Integration Guide
6.0 Connection
The USB VersaPad is available in two connec tion methods for bo th da ta and bu tton
connections.
Fl at Flexible Cable interface (FFC)
W ire to Board Header Connector interface
6.1 Molex Headers
One connector option for the VersaP ad is to use wire to board header conn ec tors. Th e J7
header (Molex #53261-0471) is used for con nec ting ex ternal mous e buttons to the
VersaPad PCBA. The J6 header (Molex #53261-0871) is the VersaPad USB
communication header.
6.2 Molex Header Cables
The mating wire harness cable to the wire to board connector is not shipped with the
standard product. The Mo lex connector series #51021 a re designed to mate with the J6
and J7 headers. The metallic contacts that slip into the #51021 housing can be either
50079-8 or 50058-8. The 5007 9 contacts accept wires AWG 26-28, and the 50058 contacts
accept wires AWG 28-32.
6.3 Flat Flex Cable Connector (FFC)
The VersaPad is also available in a FFC connec tor op tion fo r the USB and exte rnal bu tton
connections. Refer to specification for FCI SFV4R-1S T E1 LF for further details.
6.4 Flex Cable
The flexible cable, not shipped with the standard module, shall be designated for insertion
into FFC connector. An example cable is Parlex 050R04-76B. Refer to the FCI connector
specification for cable geometry re qu irements if you are designing a custom FPC cable
interface.
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6.5 Molex Connector Pin-out
The following figure and table shows the pin-o u t for Molex head er conn ec tions to the
J6 and J7 headers.
USB VersaPad®
Integration Guide
J6 Pin Signal
1 VCC +5V 1 Left Button
2 D+ D+ 2 Right Button
3 D- D- 3 Ground
4 GND Ground 4 Center Button
5 GND Ground
6 GND Ground
7 NC --
8 NC --
Figure 9: Molex Header Pin-Outs
Signal
Description
Table 1: J6 & J7 Molex Header Pin-Outs
J7 Pin Signal
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6.6 FFC Connector Pin-out
The following figure and table shows the pin-o u t for Molex head er conn ec tions to the
J2 and J3 components.
USB VersaPad®
Integration Guide
J2 Pin Signal
1 VCC +5V 1 Left Button
2 D- D- 2 Right Button
3 D+ D+ 3 Ground
4 GND Ground 4 Center Button
Figure 10: FFC Connector Pin-Outs
Signal
Description
Table 2: J2 & J3 FFC Connector Pin-Outs
J3 Pin Signal
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6.7 Cable Options
The following illustrations show the stan dar d In ter link cable options .
USB VersaPad®
Integration Guide
Figure 11: USB VersaPad Standard Cable Options
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7.0 USB Information
Communication from the host to the microprocessor is done via USB and:
Uses the low speed USB standard
Is compatible with any USB 1.1 or 2.0 host
Enumerates as a HID device
Uses the standard Windows mouse driver
The microprocessor reports data to the host at a rate of 50 reports/sec.
7.1 Device PID and VID
IC ’s Product ID (PID): 0x0001
Interlink Electronics’ Vendor ID (VID): 0x214A
7.2 Data Packet
The data packet from the chip is organize d as.
Byte 0
o Bit 0 is the Left Button status
o Bit 1 is the Right Button status
o Bit 2 is the Middle button status
Byte 1 reports the X direction. The values range from -127 to +127 counts.
Byte 2 reports the Y direction. The values range from -127 to +127 counts.
USB VersaPad®
Integration Guide
7.3 USB Suspend Mode
The module will respond to suspend command from the host by entering ‘sleep mode’ until
awakened by the host. While in suspend mode, the chip will go in to a low current draw
mode.
7.4 Operating Voltage and Current
The USB VersaPad is bus power ed ; therefore, it operates at 5V. Under normal operation,
the device draws approximately 15mA. During suspend mode the chip enters a low current
mode. In this mode the chip will draw no more than 25nA.
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8.0 Drawings and Dimensions
USB VersaPad®
Integration Guide
Figure 12: Overall dimensions of VersaPad. All dimensions are in mm.
Note: A detailed 3D CAD model of Interlink’s VersaPad geometry can be found
on our website at
www.interlinkelectronics.com
www.interlinkelectronics.com/Support.
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USB VersaPad®
Integration Guide
Figure 13: VersaPad default orientation
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9.0 Orderable Part Numbers
Ha rdware Development Kit, 54-00007
Vers aPad USB Module with FFC Connectors
Vers aPad USB Module with Molex board to Wire Connectors
VersaPad USB Demo with Cable
Demo Mod el Grap hic O verlay
12 inch Wire Cable Harness
2 FFC Cables
3 FFC Connectors
1 USB Flash Drive with Product Literature
VersaPad USB Datasheet
Versa Pad USB Inte gration Gu ide
Ve rsaPad USB Module with FFC Connectors (54-00030)
USB VersaPad®
Integration Guide
Ve rsaPad USB Module with Molex Board to Wire Connectors (54-00031)
Ve rsaPad USB Module with FFC All fe atu re s Disabled (54-00061)
Ve rsaPad USB Module with Molex All features D is ab led (54-00063)
12 inch Wire Cable Harness (14-16576)
USB Cable Assembly (14-00054)
USB Cable Assembly with Strain Relief (14-00108)
10.0 Intellectual Property & Other Legal Matters
Interlink Electronics holds several domestic and international patents for its Force Sensing
Resistor technology. FSR, Force Sensing Resistor, and VersaPad are company trademarks. All
other trademarks are the property of their respec tive owners .
The product information contained in this document provides general informa tion and
guidelines only and must not be used as an implied contract with Interlink Electronics.
Acknowledging our policy of c on t inu al product development, we reser ve the right to change,
without notice, any detail in this publication. Since Interlink Electronics has no control over the
conditions and method of use o f o ur products, we suggest that any potential user confirm their
suitability for their own application.
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11.0 Contact Interlink Electronics
United States
Corporate Office
Interlink Electronics, Inc.
546 Flynn Road
Camarillo, CA 93012, USA
Phone: +1-805-484-8855
Fax: +1-805-484-9457
Web: www.interlinkelectronics.com
Sales and support: sales@interlinkelectronics.com
Japan
Japan Sales Office
Kannai-Keihin Bldg. 10 F/1004
2-4-2 Ougi-cyo, Naka-ku
Yokohama-shi, Kanagawa-ken 231-0027
Japan
Phone: +81-45-263-6500
Fax: +81-45-263-6501
Web: www.interlinkelec.co.jp
USB VersaPad®
Integration Guide
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