While touch sensing is commonplace for single points of contact, multi-touch sensing enables a user to interact with a system with more than one finger at a time, as in chording and bi-manual operations. Such sensing devices are inherently also able to accommodate multiple users simultaneously, which is especially useful for larger interaction scenarios such as interactive walls and tabletops.

Since refining the FTIR (frustrated total internal reflection) sensing technique, we've been experimenting with a wide variety of application scenarios and interaction modalities that utilize multi-touch input information. These go far beyond the "poking" actions you get with a typical touchscreen, or the gross gesturing found in video-based interactive interfaces. It is a rich area for research, and we are extremely excited by its potential for advances in efficiency, usability, and intuitiveness. It's also just so much fun!

Our technique is force-sensitive, and provides unprecedented resolution and scalability, allowing us to create sophisticated multi-point widgets for applications large enough to accommodate both hands and multiple users.

The drafting table style implementation shown here measures 36"x27", is rear-projected, and has a sensing resolution of better than 0.1" at 50Hz. Stroke event information is sent to applications using the lightweight OSC protocol over UDP.

TSS: Touch Sensing Software from Freescale - How to Create a TSS Project

The TSS - Touch Sensing Software solution transforms a standard micrcontroller into a proximity capacitive touch sensor controller. The touch sensor controller has the ability to control multiple touch pad configurations and mechanical keys while maintaining its standard MCU control functionality. The Touch Sense Library enables capacitive sensing for the entire Freescale S08 family of microcontrollers. The Touch Sense library provides commonly used touch sense decoding structures as keypad, rotary, and slider. It is implemented in a software layered architecture to enable easy integration into the application code, easy migration to other Freescale microcontrollers, and for customization by customers.
The Touch Sensing Software requires CodeWarrior Development Studio Special Edition Microcontrollers Version 6.2 to be installed in the host PC.

TSS - Touch Sensing Software - Installation

The TSS library files are distributed in the form of binary library and source code for compile time configuration and optimization. To install the TSS on your host PC:

The application project that is using the TSS library makes only a reference to the TSS files. You can copy the library files into the application project directory or can leave them in the installation folder. Leaving the library files in the installation folder enables you to upgrade your project to newer TSS library versions more easily in the future.
After CodeWarrior and the Freescale Touch Sensing Software (TSS) are installed, you can begin creating projects that utilize the TSS. This chapter discusses the steps required to create a new TSS project.

How to Create a TSS Project
To create a TSS project using the New Project wizard, perform these steps:
1. Select Start > Programs > Freescale CodeWarrior > CodeWarrior for Microcontrollers > CodeWarrior IDE. 2. The IDE launches as shown in Figure 1. From the Startup window, select Create New Project.

The Microcontrollers New Project wizard appears as shown in Fig. 2:

Microcontrollers New Project Wizard — Device and Connection

3. select the derivative for the MCU family to use in the project being created. Also select the debugger connection and click on the Next button.

4. Set the programming language supported in the project. Because the Touch Sensing Library is compiled in C, select C checkbox. Also, set the project name and the location, and click on the Next button.

Microcontrollers New Project Wizard — Project Parameters

5. Add existing files into the project. You can use this step to add any of your prepared source files to the project. The TSS library files could be added now, but it is more convenient to add them to the project later after it is created.

Microcontrollers New Project — Add Additional Files

6. Select either None or Device Initialization option, because the Processor Expert option adds too much overhead for the TSS to be able to work adequately. Click on the Next button to add C/C++ options.

Microcontrollers New Project — Rapid Application Development Options

7. Perform the following steps to select the startup code, the memory model, and the floating point support.

Microcontrollers New Project - C/C++ Options

Click on the Next button to open the PC-Lint window.
8. PC-Lint™ is a program from Gimpel® that can help you identify common programming mistakes or suspicious lines in source code. This window provides you an opportunity to create a target to use the PC-Lint software.

Microcontrollers New Project — PC-Lint

9. When the project is generated, you must create the TSS_SystemSetup.h configuration header file in your application folder. For an easy start, copy one of example files provided in the “examples” folder to your project folder and modify its content.

10. With the TSS_SystemSetup.h file located within the application directory, you must compile the new project. From the CodeWarrior IDE menu bar, click Project > Make to compile.