PSoC™ 4 MCU: CAPSENSE™ with Flanking Sensor Suppression

Disclaimer: This is a community code example (CCE) released for the benefit of the community users. These projects have only been tested for the listed BSPs, tools versions, and toolchains documented in this readme. They are intended to demonstrate how a solution / concept / use-case can be achieved on a particular device. For official code examples, please click here.

This code example implements Flanking Sensor Suppression (FSS) in PSoC™ 4 devices. FSS eliminates false touches by distinguishing between signals from closely spaced buttons. In the project, three sensors have been used to demonstrate FSS. Whenever multiple sensors are touched, only the sensor whose touch was detected first remains active, and the other sensors are rendered inactive, i.e., their touch (if any) is rendered invalid until the sensor whose touch was detected first is active. This eliminates sensors, which are closely spaced, from being falsely triggered at the same time.

Requirements

ModusToolbox™ software v2.4

Note: This code example version requires ModusToolbox™ software version 2.4 and may not be compatible with other versions.
Board support package (BSP) minimum required version: 2.0.0
Programming language: C
Associated parts: PSoC™ 4000S and PSoC™ 4100S plus

Supported toolchains (make variable 'TOOLCHAIN')

GNU Arm® embedded compiler v9.3.1 (GCC_ARM) - Default value of TOOLCHAIN

Supported kits (make variable 'TARGET')

PSoC™ 4100S plus prototyping kit (CY8CKIT-149) - Default value of TARGET
PSoC™ 4000S CAPSENSE™ prototyping kit (CY8CKIT-145-40XX)

Hardware setup

This example uses the board's default configuration. See the kit user guide to ensure that the board is configured correctly.

Note: The PSoC™4 kits ship with KitProg2 installed. The ModusToolbox™ requires KitProg3. Before using this code example, make sure that the board is upgraded to KitProg3. The tool and instructions are available in the Firmware Loader GitHub repository. If you do not upgrade, you will see an error like "unable to find CMSIS-DAP device" or "KitProg firmware is out of date".

Software setup

This example requires no additional software or tools.

Using the code example

Create the project and open it using one of the following:

In Eclipse IDE for ModusToolbox™ software

Click the New Application link in the Quick Panel (or, use File > New > ModusToolbox Application). This launches the Project Creator tool.
Pick a kit supported by the code example from the list shown in the Project Creator - Choose Board Support Package (BSP) dialog.

When you select a supported kit, the example is reconfigured automatically to work with the kit. To work with a different supported kit later, use the Library Manager to choose the BSP for the supported kit. You can use the Library Manager to select or update the BSP and firmware libraries used in this application. To access the Library Manager, click the link from the Quick Panel.

You can also just start the application creation process again and select a different kit.

If you want to use the application for a kit not listed here, you may need to update the source files. If the kit does not have the required resources, the application may not work.
In the Project Creator - Select Application dialog, choose the example by enabling the checkbox.
(Optional) Change the suggested New Application Name.
The Application(s) Root Path defaults to the Eclipse workspace which is usually the desired location for the application. If you want to store the application in a different location, you can change the Application(s) Root Path value. Applications that share libraries should be in the same root path.
Click Create to complete the application creation process.

For more details, see the Eclipse IDE for ModusToolbox™ software user guide (locally available at {ModusToolbox™ software install directory}/ide_{version}/docs/mt_ide_user_guide.pdf).

In command-line interface (CLI)

ModusToolbox™ software provides the Project Creator as both a GUI tool and the command line tool, "project-creator-cli". The CLI tool can be used to create applications from a CLI terminal or from within batch files or shell scripts. This tool is available in the {ModusToolbox™ software install directory}/tools_{version}/project-creator/ directory.

Use a CLI terminal to invoke the "project-creator-cli" tool. On Windows, use the command line "modus-shell" program provided in the ModusToolbox™ software installation instead of a standard Windows command-line application. This shell provides access to all ModusToolbox™ software tools. You can access it by typing modus-shell in the search box in the Windows menu. In Linux and macOS, you can use any terminal application.

This tool has the following arguments:

Argument	Description	Required/optional
`--board-id`	Defined in the `<id>` field of the BSP manifest	Required
`--app-id`	Defined in the `<id>` field of the CE manifest	Required
`--target-dir`	Specify the directory in which the application is to be created if you prefer not to use the default current working directory	Optional
`--user-app-name`	Specify the name of the application if you prefer to have a name other than the example's default name	Optional

The following example will clone the "CAPSENSE™ with Flanking Sensor Suppression" application with the desired name "MyCapsenseFSS" configured for the CY8CKIT-149 BSP into the specified working directory, C:/mtb_projects:

project-creator-cli --board-id CY8CKIT-149 --app-id cce-mtb-psoc4-capsense-fss --user-app-name MyCapsenseFSS --target-dir "C:/mtb_projects"

Note: The project-creator-cli tool uses the git clone and make getlibs commands to fetch the repository and import the required libraries. For details, see the "Project creator tools" section of the ModusToolbox™ software user guide (locally available at {ModusToolbox™ software install directory}/docs_{version}/mtb_user_guide.pdf).

In third-party IDEs

Use one of the following options:

Use the standalone Project Creator tool:
1. Launch Project Creator from the Windows Start menu or from {ModusToolbox™ software install directory}/tools_{version}/project-creator/project-creator.exe.
2. In the initial Choose Board Support Package screen, select the BSP, and click Next.
3. In the Select Application screen, select the appropriate IDE from the Target IDE drop-down menu.
4. Click Create and follow the instructions printed in the bottom pane to import or open the exported project in the respective IDE.

Use command-line interface (CLI):
1. Follow the instructions from the In command-line interface (CLI) section to create the application, and then import the libraries using the make getlibs command.
2. Export the application to a supported IDE using the make <ide> command.
3. Follow the instructions displayed in the terminal to create or import the application as an IDE project.

For a list of supported IDEs and more details, see the "Exporting to IDEs" section of the ModusToolbox™ software user guide (locally available at {ModusToolbox™ software install directory}/docs_{version}/mtb_user_guide.pdf).

Operation

Connect the board to your PC using the provided USB cable through the KitProg3 USB connector.
Program the board using one of the following:
Using Eclipse IDE for ModusToolbox™ software
1. Select the application project in the Project Explorer.
2. In the Quick Panel, scroll down, and click <Application Name> Program (KitProg3_MiniProg4).
Using CLI

From the terminal, execute the make program command to build and program the application using the default toolchain to the default target. The default toolchain and target are specified in the application's Makefile but you can override those values manually:
```
make program TARGET=<BSP> TOOLCHAIN=<toolchain>
```
Example:
```
make program TARGET=CY8CKIT-149 TOOLCHAIN=GCC_ARM
```
After programming, the application starts automatically. The statuses of the on-board user buttons can be visually observed through their corresponding on-board user LEDs. By default or during no-press condition, LEDs are turned off. A button press is visually indicated by turning on the corresponding LED.
Press more than one button to observe the FSS algorithm in action i.e., LED of only the first pressed button glows and all other LEDs would be turned off.

Debugging

You can debug the example to step through the code. In the IDE, use the <Application Name> Debug (KitProg3_MiniProg4) configuration in the Quick Panel. For details, see the "Program and debug" section in the Eclipse IDE for ModusToolbox™ software user guide.

Design and implementation

The project contains two button widgets, one of them configured in CSD sensing mode and the other in CSX sensing mode. See the "CAPSENSE™ CSD sensing method (third- and fourth-generation)" and "CAPSENSE™ CSX sensing method (third- and fourth-generation)" sections in the AN85951 – PSoC™ 4 and PSoC™ 6 MCU CAPSENSE™ design guide for details on CAPSENSE™ CSD and CSX sensing modes. The CSD widget contains two sensing elements whereas the CSX widget contains one sensing element (1RX x 1 TX).

These three sensing elements are mapped to the on-board user buttons. The status of an on-board user button is conveyed by controlling the LED state. The LED turns on when a button press is registered and remains in off-state when the button is not pressed.

The flanking sensor suppression (FSS) algorithm can be applied on selective buttons as per user's choice. By default, FSS is applied on all buttons. FSS_ENABLE_MASK, present in CapSense_FSS_Algorithm.c, decides whether the FSS algorithm is applied on a button or not. FSS_ENABLE_MASK can be decoded as shown in Figure 1. If a bit is zero, then FSS is not applied to that sensor and if a bit is 1, then FSS is applied to that sensor.

Figure 1. Decoding FSS_ENABLE_MASK

Refer PSoC™ 4 MCU: CAPSENSE™ CSD button tuning code example to tune CSD sensors and refer PSoC™ 4 MCU: CAPSENSE™ CSX button tuning code example to tune CSX sensors.

Resources and settings

Figure 2: EZI2C Settings

Table 1. Application resources

Resource	Alias/object	Purpose
SCB (I2C) (PDL)	CYBSP_EZI2C	EZI2C slave driver to communicate with the CAPSENSE™ tuner
CAPSENSE™	CYBSP_CSD	CAPSENSE™ driver to interact with the CSD and CSX hardware and interface CAPSENSE™ sensors
Digital Pins	CYBSP_LED_BTN0 CYBSP_LED_BTN1 CYBSP_LED_BTN2	To visually indicate the status of buttons

Table 2 shows the pins used for buttons and LEDs. Here, LED0 corresponds to SNS0 of Button0, LED1 corresponds to SNS1 of Button0 and LED2 corresponds to Button1.

Table 2. Pins used for CAPSENSE™ sensors and LEDs

Development kit	Button0 (CSD)	Button1 (CSX)	LED0	LED1	LED2
CY8CKIT-149	SNS0 - P4[4] SNS1 - P4[5]	RX - P4[6] TX - P0[2]	P5[7]	P5[5]	P5[2]
CY8CKIT-145-40XX	SNS0 - P1[6] SNS1 - P1[5]	RX - P1[4] TX - P1[3]	P3[6]	P3[5]	P3[4]

Related resources

Resources	Links
Application notes	AN79953 – Getting started with PSoC™ 4 AN85951 – PSoC™ 4 and PSoC™ 6 MCU CAPSENSE™ design guide
Code examples	Using ModusToolbox™ software on GitHub
Device documentation	PSoC™ 4000S datasheet PSoC™ 4000S architecture technical reference manual PSoC™ 4000S register technical reference manual PSoC™ 4100S Plus datasheet PSoC™ 4100S Plus architecture technical reference manual PSoC™ 4100S Plus register technical reference manual
Development kits	Visit PSoC™ and FMx MCU Board & Kit Finder to find a list of various PSoC™ evaluation boards.
Libraries on GitHub	mtb-pdl-cat2 – PSoC™ 4 peripheral driver library (PDL) mtb-hal-cat2 – Hardware abstraction layer (HAL) library
Middleware on GitHub	capsense – CAPSENSE™ library and documents psoc4-middleware – Links to all PSoC™ 4 MCU middleware
Tools	Eclipse IDE for ModusToolbox™ software – ModusToolbox™ software is a collection of easy-to-use software and tools enabling rapid development with Infineon MCUs, covering applications from embedded sense and control to wireless and cloud-connected systems using AIROC™ Wi-Fi and Bluetooth® connectivity devices.

Other resources

Infineon provides a wealth of data at www.infineon.com to help you select the right device, and quickly and effectively integrate it into your design.

Document history

Document title: CCE236271 - PSoC™ 4 MCU: CAPSENSE™ with Flanking Sensor Suppression

Version	Description of change
1.0.0	New community code example

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