PSoC™ 4: MSC CAPSENSE™ Liquid tolerant touchpad

This code example demonstrates how to use the CAPSENSE™ middleware to detect a finger touch position with gestures on a self-capacitance-based touchpad widget in PSoC™ 4 devices with multi sense converter (MSC).

View this README on GitHub.

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Requirements

ModusToolbox™ v3.1 or later (tested with v3.1)
Board support package (BSP) minimum required version: 3.1.0
Programming language: C
Associated parts: PSoC™ 4100S Max

Supported toolchains (make variable 'TOOLCHAIN')

GNU Arm® Embedded Compiler v11.3.1 (GCC_ARM) - Default value of TOOLCHAIN
Arm® Compiler v6.16 (ARM)
IAR C/C++ Compiler v9.30.1 (IAR)

Supported kits (make variable 'TARGET')

PSoC™ 4100S Max Pioneer Kit (CY8CKIT-041S-MAX) – Default value of TARGET

Hardware setup

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

Please follow the CY8CKIT-041S-MAX Kit rework section as mentioned in the kit user guide to provide performance improvement for CSD (self-capacitance) sensing.

Note: The PSoC™ 4 kits ship with KitProg2 installed. 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 If you do not upgrade, you will see an error like "unable to find CMSIS-DAP device" or "KitProg firmware is out of date".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™

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 must be in the same root path.
Click Create to complete the application creation process.

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

In command-line interface (CLI)

ModusToolbox™ 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™ 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™ installation instead of a standard Windows command-line application. This shell provides access to all ModusToolbox™ 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.

The "project-creator-cli" 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 clones the "MSCcapsenseliquidtoleranttouchpad" application with the desired name "MSCcapsenseliquidtoleranttouchpad" configured for the CY8CKIT-041S-MAX BSP into the specified working directory, C:/mtb_projects:

project-creator-cli --board-id CY8CKIT-041S-MAX --app-id mtb-example-psoc4-msc-capsense-liquid-tolerant-touchpad --user-app-name MSCcapsenseliquidtoleranttouchpad --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™ user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mtb_user_guide.pdf).

To work with a different supported kit later, use the Library Manager to choose the BSP for the supported kit. You can invoke the Library Manager GUI tool from the terminal by using the make library-manager command or use the Library Manager CLI tool (library-manager-cli) to change the BSP.

The "library-manager-cli" tool has the following arguments:

Argument	Description	Required/optional
`--add-bsp-name`	Name of the BSP that should be added to the application	Required
`--set-active-bsp`	Name of the BSP that should be as active BSP for the application	Required
`--add-bsp-version`	Specify the version of the BSP that should be added to the application if you do not wish to use the latest from manifest	Optional
`--add-bsp-location`	Specify the location of the BSP (local/shared) if you prefer to add the BSP in a shared path	Optional

The following example adds the CY8CKIT-041S-MAX BSP to the already created application and makes it the active BSP for the application:

library-manager-cli --project "C:/mtb_projects/mtb-example-psoc4-msc-capsense-liquid-tolerant-touchpad" --add-bsp-name CY8CKIT-041S-MAX --add-bsp-version "latest-v3.X" --add-bsp-location "local"

library-manager-cli --project "C:/mtb_projects/mtb-example-psoc4-msc-capsense-liquid-tolerant-touchpad" --set-active-bsp APP_CY8CKIT-041S-MAX

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™ 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.
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™ user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mtb_user_guide.pdf).

Operation

Connect the FFC cable between J9 on the PSoC™ 4100S Max Pioneer Board and J2 on the capacitive sensing expansion board. Connect a USB 2.0 Type-A to Micro-B cable on J8 (USB Micro-B connector) as shown in Figure 1 to power the device.

Figure 1. Connecting the CY8CKIT-041S-MAX kit with a capacitive sensing expansion board to a PC
Program the board using one of the following:
Using Eclipse IDE for ModusToolbox™
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 is specified in the application's Makefile, but you can override this value manually:
```
make program TARGET=<BSP> TOOLCHAIN=<toolchain>
```
Example:
```
make program TARGET=CY8CKIT-041S-MAX TOOLCHAIN=GCC_ARM
```
To test the application, tap your finger once over the CAPSENSE™ Touchpad and confirm that the LED1 turns ON; tap it again and confirm that the LED1 turns OFF.
Scroll your finger slowly Up, Down, Right, and Left on the touchpad and confirm that the LED1 changes brightness.
Flick your finger across the touchpad Up, Down, Right, and Left, and confirm that the LED1 changes brightness.
Tap the touchpad once with two fingers and confirm that the LED3 turns ON; tap it again and confirm that the LED3 turns OFF.
Perform a two-finger zoom-in and zoom-out to confirm that LED1 changes brightness.
Use a water dropper to place water droplets on top of the touchpad. Observe that all LEDs are in OFF state, indicating that no false trigger occurs due to the presence of water.
Repeat the steps from 3 to 7 and observe the corresponding LEDs functionality in the presence of water.
Open a terminal program and select the KitProg3 COM port. Set the serial port parameters to 8N1 and 115200 baud.

Figure 2. UART - Peripheral settings

Figure 3. Sample output as displayed on Tera Term

Figure 4. Capsense tuner sample output
You can also monitor the CAPSENSE™ data using the CAPSENSE™ tuner application as follows:

Monitor data using CAPSENSE™ tuner
1. Open CAPSENSE™ tuner from the Tools section in the IDE Quick Panel.
  
  You can also run the CAPSENSE™ tuner application standalone from the {ModusToolbox™ install directory}/ModusToolbox/tools_{version}/capsense-configurator/capsense-tuner. In this case, after opening the application, select File > Open and open the design.cycapsense file of the respective application, which is present in the {Application root directory}/COMPONENT_CUSTOM_DESIGN_MODUS/TARGET_<BSP-NAME> folder.
  
  See the ModusToolbox™ user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mtb_user_guide.pdf) for options to open the CAPSENSE™ tuner application using the CLI.
2. Ensure the kit is in CMSIS-DAP bulk mode (KitProg3 Status LED is ON and not blinking). See Firmware Loader to learn how to update the firmware and switch modes in KitProg3.
3. In the tuner application, click on the Tuner Communication Setup icon or select Tools > Tuner Communication Setup. In the window that appears, select the I2C checkbox under KitProg3 and configure it as follows:
  - I2C address: 8
  - Sub-address: 2-Bytes
  - Speed (kHz): 1000
  These are the same values set in the EZI2C resource.
  
  Figure 5. Tuner communication setup parameters
4. Click Connect or select Communication > Connect to establish a connection.
  
  Figure 6. Tuner Communication Setup parameters
5. Click Start or select Communication > Start to start data streaming from the device.
  
  The tuner displays the data from the sensor in the Widget View, Graph View, and Touchpad View tabs.
  
  Figure 7. Start tuner communication
6. Set the Read Mode to Synchronized mode. Under the Widget View tab, you can see the touchpad widget highlighted in blue color when you touch it.
  
  Figure 8. Widget View tab of CAPSENSE™ Tuner
7. You can view the raw count, baseline, difference count, and status for each sensor, as well as the touchpad position, in the Graph View tab. For example, to view the sensor data for touchpad 0, select Touchpad0_Col0 under Touchpad0.
  
  Figure 9. Widget View tab of CAPSENSE™ Tuner
8. The Touchpad View tab shows the heatmap view, and the finger movement can be visualised on the same.
  
  Figure 10. Graph View of CAPSENSE™ Tuner
9. See the Widget/Sensor Parameters section in the CAPSENSE™ tuner window. The compensation CDAC values for each touchpad sensor element calculated by the CAPSENSE™ resource are displayed as shown in Figure 10.
10. Ensure that the SNR is greater than 5:1.
Non-reporting of false touches and the linearity of the position graph indicate proper tuning.

Note: The touchpad performance can be further enhanced by configuring the board to connect the hatch pattern to shield. To do so, see the kit user guide for the board connection settings. Enable the shield signals in the CAPSENSE™ Configurator as shown in Figure 11. Then, follow the tuning process explained in Tuning procedure to retune the touchpad.

Figure 11. Enabling shield signals in CAPSENSE™ configurator

Note: When Flip Y axis option is enabled in the CapSense tuner in the widget selection section, the TouchpadView/GestureView window shows opposite gesture detection. This behaviour will be fixed in future release.

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™ user guide.

Note: By default, the debug port is disabled in the kit to achieve low power. If debugging is required, do the following:

Enable the Debug Mode under the Systems tab in the Device Configurator and change the Debug Mode setting to SWD.
Select the pins P3[2] (SWDIO) and P3[3] (SWDCK) under the SWD pin setting.
Select the Drive mode of both the pins as "Strong Drive,Input buffer on" under the Pins tab in the Device Configurator.

Design and implementation

The project contains one proximity widget and one touchpad widget configured in CSD sensing mode. To demonstrate the gesture functionality of the touchpad, PSoC™ 4 controls LEDs, whose brightness is controlled based on the position detected on the touchpad and turned ON and OFF based on the detected gestures. Alternatively, the CAPSENSE™ software tuner can be used for real-time tuning and monitoring of detected gestures.

The project uses the CAPSENSE™ middleware (see ModusToolbox™ user guide for more details on selecting a middleware). See AN85951 - PSoC™ 4 and PSoC™ 6 MCU CAPSENSE™ design guide for more details on CAPSENSE™ features and usage.

The ModusToolbox™ software provides a GUI-based tuner application for debugging and tuning the CAPSENSE™ system. The CAPSENSE™ tuner application works with EZI2C and UART communication interfaces. This project has an SCB block configured in EZI2C mode to establish communication with the on-board KitProg, which in turn enables reading the CAPSENSE™ raw data by the CAPSENSE™ tuner. See EZI2C - Peripheral settings.

The CAPSENSE™ data structure that contains the CAPSENSE™ raw data is exposed to the CAPSENSE™ tuner by setting up the I2C communication data buffer with the CAPSENSE™ data structure. This enables the tuner to access the CAPSENSE™ raw data for tuning and debugging CAPSENSE™.

The WDT in PSoC™ 4 is a 16-bit timer and uses the internal low-speed oscillator (ILO) clock of 40 kHz as a source. The accuracy of ILO is (- 50% to +100%). Therefore, the match value of WDT is set after compensating the ILO with IMO. The firmware flow is as follows:

Enable the ILO, which is the source for the WDT. Start ILO measurement and get the value of ilo_compensated_counts which must be set after every interrupt match.
Write the match value. The WDT can generate an interrupt when the WDT counter reaches the match count. The match count is generated using DESIRED_WDT_INTERVAL_MS.
Enable interrupt generation and assign the interrupt service routine(wdt_isr).
Enable the WDT. Because the ILO has low accuracy, the ilo_compensated_counts are calculated, and the match value of the WDT is updated following a WDT interrupt.
The System is put into Deep Sleep in idle mode to save power. Because the watchdog timer works on a low-frequency clock (LFCLK), its operation will not be affected when the system is put into Deep Sleep mode. The watchdog timer interrupt will wake the device from Deep Sleep mode.

Set up the VDDA supply voltage and Debug mode in the Device Configurator

Open the Device Configurator from the Quick Panel.
Navigate to the System tab. Select the Power resource, and set the VDDA value under Operating conditions.
By default, SWD pins are active in all device power modes. Disable Debug mode to disable SWD pins and thereby reduce power consumption as follows:

Figure 12. Disable Debug mode in the System tab of Device Configurator

Resources and settings

Figure 13. EZI2C - Peripheral settings

The following ModusToolbox™ resources are used in this example:

Table 1. Application resources

Resource	Alias/object	Purpose
CAPSENSE™	CYBSP_MSC0,CYBSP_MSC1	CAPSENSE™ driver to interact with the MSC hardware and interface the CAPSENSE™ sensors
SCB (I2C) (PDL)	CYBSP_EZI2C	EZI2C driver to interface with CAPSENSE™ tuner
PWM(TCPWM)	pwm2	Controls the duty cycle/Generates a signal at a particular frequency based on the period and compares values
UART(PDL)	scb_1	Send to and receive data from the UART terminal
LED (BSP)	CYBSP_USER_LED	User LED to show the output
WDT (PDL)	-	WDT driver to configure the hardware resource

Related resources

Resources	Links
Application notes	AN79953 – Getting started with PSoC™ 4
Code examples	Using ModusToolbox™ on GitHub
Device documentation	PSoC™ 4 datasheets PSoC™ 4 technical reference manuals
Development kits	Select your kits from the Evaluation board finder.
Libraries on GitHub	mtb-pdl-cat2 – PSoC™ 4 Peripheral Driver Library (PDL) mtb-hal-cat2 – Hardware Abstraction Layer (HAL) library
Tools	ModusToolbox™ – ModusToolbox™ 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: CE238039 – PSoC™ 4: MSC CAPSENSE™ Liquid tolerant touchpad

Version	Description of change
1.0.0	New code example

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mtb-example-psoc4-msc-capsense-liquid-tolerant-touchpad/README.md