1015 User Guide

Getting Started

Checking the Contents

You should have received: A PhidgetLinearTouch board. A custom USB cable

Connecting the Pieces

Connect the PhidgetLinearTouch to your computer using the custom USB cable included.

Testing Using Windows 2000 / XP / Vista / 7

Make sure you have the current version of the Phidget library installed on your PC. If you don't, follow these steps:

1. Go to the Quick Downloads section on the Windows page
2. Download and run the Phidget21 Installer (32-bit, or 64-bit, depending on your system)
3. You should see the icon on the right hand corner of the Task Bar.

Running Phidgets Sample Program

Double clicking on the icon loads the Phidget Control Panel; we will use this program to ensure that your new Phidget works properly.

The source code for the InterfaceKit-full sample program can be found in the quick downloads section on the C# Language Page. If you'd like to see examples in other languages, you can visit our Languages page.

Updating Device Firmware

If an entry in this list is red, it means the firmware for that device is out of date. Double click on the entry to be given the option of updating the firmware. If you choose not to update the firmware, you can still run the example for that device after refusing.

Double Click on the icon to activate the Phidget Control Panel and make sure that the PhidgetLinearTouch is properly attached to your PC.		File:1015 0 Control Panel Screen.jpg
Double Click on Phidget Touch Slider in the Phidget Control Panel to bring up InterfaceKit-full and check that the box labelled Attached contains the word True. As you bring your finger closer to the board and touch the board, tick marks will appear in the Digital In boxes. The left one shows “touch” and the right one shows “proximity”. Move your finger along the backside of the PhidgetLinearTouch and watch the numbers in the Analog box change from 0 to 1000. The numbers are only significant when both Digital In boxes are “tick marked”. Adjusting the input sensitivity with the sensitivity slider changes the number of discrete steps that will fire the on-sensor-change event.		File:1015 0 InterfaceKit Screen.jpg

Testing Using Mac OS X

1. Go to the Quick Downloads section on the Mac OS X page
2. Download and run the Phidget OS X Installer
3. Click on System Preferences >> Phidgets (under Other) to activate the Preference Pane
4. Make sure that the PhidgetLinearTouch is properly attached.
5. Double Click on PhidgetLinearTouch in the Phidget Preference Pane to bring up the InterfaceKit-full Sample program. This program will function in a similar way as the Windows version.

Using Linux

For a step-by-step guide on getting Phidgets running on Linux, check the Linux page.

Technical Details

The PhidgetLinearTouch is actually a capacitive-charge sensor, detecting changes in the capacitance between the on-board electrodes and the object making contact. The side of the circuit board opposite the connector and components is the side intended for contact. The internal sensor used for charge-detection is a Quantum Research Group QT401 Sensor.

Device Inputs

The PhidgetLinearTouch appears to the Phidget software libraries as an InterfaceKit. Sliding a finger along the touch sensor varies the Analog Input 0 value from 0 to 1000 in approximately 125 discrete steps. When the finger is removed, the final measured value is retained. Two Digital Inputs are also utilized to convey additional information: Digital Input 0 appears True when contact is made with the electrodes on the Phidget, and Digital Input 1 appears True when a finger or contacting object comes in close proximity to the electrodes. The two Digital Inputs are intended to be used as a quality measure, allowing the developer to trust the Analog Input value only when both Digital Inputs are true.

Input	Range	Description
Analog Input 0	0 - 1000	Analog value representing touch position
Digital Input 0	True/False	True indicates physical contact with electrode
Digital Input 1	True/False	True indicates proximity to electrodes

For many projects it is required that the highest and lowest available values be more readily accessible than the full range. The PhidgetLinearTouch board has been designed so that the end-zones of the touch area have a greater contact area, allowing for effective maximum/minimum value control. If it is desired to use the touch slider as an array of buttons, or a combination of an array of buttons and a smaller slide-touch area, one must only interpret specific sub-ranges of sensor values differently in software depending upon the intended use. If sub-ranges of values are to be used as buttons, it is recommended that a small range of sensor values be left between the subranges where a null-response is observed.

Dielectric Separation

The PhidgetLinearTouch has been left without components on the contact side so that it may be mounted behind a sheet of glass or plastic. The recommended thickness of separation material is 1/8 inch. Silicon adhesive is recommended when attaching the Phidget to the material; standing the PhidgetLinearTouch off or creating space between the separation material and the Phidget can cause false-triggering to occur. It should be noted that materials thicker than 1/8” may work, but will require a larger surface area of contact to ensure proper triggering (i.e.: two fingers instead of one).