PSoC™ 4: MSCLP multitouch mutual-capacitance touchpad tuning

This code example demonstrates how to use the CAPSENSE™ middleware to detect two finger touch positions and gesture on a mutual-capacitance-based touchpad widget in PSoC™ 4 devices with multi-sense converter low-power (MSCLP).

In addition, this code example explains how to manually tune the mutual-capacitance-based touchpad for optimum performance according to parameters such as reliability, power consumption, response time, and linearity using the CSX-RM sensing technique and CAPSENSE™ Tuner GUI. Here, CAPSENSE™ crosspoint (CSX) represents the mutual-capacitance sensing technique and RM represents the ratiometric method.

View this README on GitHub.

Provide feedback on this code example.

Requirements

• ModusToolbox™ v3.2 or later

  Note: This code example version requires ModusToolbox™ version 3.2 or later, and is not backward compatible with v3.1 or older versions.

• Board support package (BSP) minimum required version: 3.2.0

• Programming language: C

• Associated parts: PSoC™ 4000T

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™ 4000T CAPSENSE™ Evaluation Kit (CY8CKIT-040T) – Default TARGET

Hardware setup

This example uses the board's default configuration. See the kit user guide to ensure that the board is configured correctly to use VDDA at 1.8 V.

Note: The PSoC™ 4 kits (except CY8CKIT-040T and CY8CKIT-041S-MAX) 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 If you do not upgrade, you will see an error like "unable to find CMSIS-DAP device" or "KitProg firmware is out of date".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

See the ModusToolbox™ tools package installation guide for information about installing and configuring the tools package.

This example requires no additional software or tools.

Using the code example

Create the project

The ModusToolbox™ tools package provides the Project Creator as both a GUI tool and a command line tool.

Use Project Creator GUI

1. Open the Project Creator GUI tool.

   There are several ways to do this, including launching it from the dashboard or from inside the Eclipse IDE. For more details, see the Project Creator user guide (locally available at {ModusToolbox™ install directory}/tools_{version}/project-creator/docs/project-creator.pdf).

2. On the Choose Board Support Package (BSP) page, select a kit supported by this code example. See Supported kits.

   Note: To use this code example 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.

3. On the Select Application page:

   a. Select the Applications(s) Root Path and the Target IDE.

   Note: Depending on how you open the Project Creator tool, these fields may be pre-selected for you.

   b. Select this code example from the list by enabling its check box.

   Note: You can narrow the list of displayed examples by typing in the filter box.

   c. (Optional) Change the suggested New Application Name and New BSP Name.

   d. Click Create to complete the application creation process.

Use Project Creator CLI

The 'project-creator-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 following example clones the "CAPSENSE™ MSCLP mutual capacitance touchpad tuning" application with the desired name "MSCLPMutualCapTouchpadTuning" configured for the CY8CKIT-040T BSP into the specified working directory, C:/mtb_projects:

project-creator-cli --board-id CY8CKIT-040T --app-id mtb-example-psoc4-msclp-mutual-capacitance-touchpad --user-app-name MSCLPMutualCapTouchpadTuning --target-dir "C:/mtb_projects"

The 'project-creator-cli' tool has the following arguments:

Argument	Description	Required/optional
--board-id	Defined in the field of the BSP manifest	Required
--app-id	Defined in the 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

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

Open the project

After the project has been created, you can open it in your preferred development environment.

Eclipse IDE

If you opened the Project Creator tool from the included Eclipse IDE, the project will open in Eclipse automatically.

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

Visual Studio (VS) Code

Launch VS Code manually, and then open the generated {project-name}.code-workspace file located in the project directory.

For more details, see the Visual Studio Code for ModusToolbox™ user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mt_vscode_user_guide.pdf).

Keil µVision

Double-click the generated {project-name}.cprj file to launch the Keil µVision IDE.

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

IAR Embedded Workbench

Open IAR Embedded Workbench manually, and create a new project. Then select the generated {project-name}.ipcf file located in the project directory.

For more details, see the IAR Embedded Workbench for ModusToolbox™ user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mt_iar_user_guide.pdf).

Command line

If you prefer to use the CLI, open the appropriate terminal, and navigate to the project directory. On Windows, use the command-line 'modus-shell' program; on Linux and macOS, you can use any terminal application. From there, you can run various make commands.

For more details, see the ModusToolbox™ tools package user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mtb_user_guide.pdf).

Operation

1. Connect the board to your PC using the provided Micro-B USB cable through the KitProg3 USB connector.

   Figure 1. Connecting the CY8CKIT-040T kit with the PC

   

2. Program the board using one of the following:

   Using Eclipse IDE

   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 target and the toolchain is specified manually:

   make program TARGET=<BSP> TOOLCHAIN=<toolchain>
   

   Example:

   make program TARGET=CY8CKIT-040T TOOLCHAIN=GCC_ARM
   

3. After programming, the application starts automatically.

Note: After programming, you see the following error message if debug mode is disabled. This can be ignored or enabling debug solves this error.

"Error: Error connecting Dp: Cannot read IDR"

4. To test the application:

   • Slide your finger over the CAPSENSE™ touchpad and notice that LED1 and LED3 turn ON with green color when touched and turn OFF when the finger is lifted.

     • LED1 brightness increases when finger is moved from bottom to up, with bottom row having minimum and top row having maximum brightness.
     • LED3 brightness increases when finger is moved from left to right, with left column having minimum and right column having maximum brightness.

   • Perform gestures on the Touchpad and observe LED2 colors mentioned as follows:

     Gesture Type	Color
     One-finger single click	Red color
     One-finger double click	Blue color
     One-finger flick in up direction	Cyan color
     One-finger flick in down direction	White color
     One-finger flick in left direction	Rose color
     One-finger flick in right direction	Orange color
     One-finger flick in other directions	Green color
     Two-finger zoom in/out	Violet color
     One-finger click & drag	Yellow color

     Note: One-finger click and drag gesture is triggered when the finger movement follows this sequence: Touchdown → Lift Off → Touchdown → Drag .

5. Do the following to monitor the CAPSENSE™ data using the CAPSENSE™ Tuner application:

   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 in standalone mode from {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}/bsps/TARGET_APP_<BSP-NAME>/config/ 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 that the kit is in CMSIS-DAP bulk mode (KitProg3 status LED is ON and not blinking). To learn how to update the firmware and switch modes in KitProg3, see Firmware-loader.

   3. In the tuner application, click on the Tuner Communication Setup icon or select Tools > Tuner Communication Setup. In the window, select the I2C checkbox under KitProg3 and configure as follows:

      • I2C address: 8
      • Sub-address: 2 bytes
      • Speed (kHz): 400

      These are the same values set in the EZI2C resource.

      Figure 2. Tuner Communication Setup parameters

      

   4. Click Connect or select Communication > Connect to establish a connection.

      Figure 3. Establish a connection

      

   5. Click Start or select Communication > Start to start data streaming from the device.

      Figure 4. Start tuner communication

      

      The Widget/Sensor parameters tab gets updated with the parameters configured in the CAPSENSE™ configurator window. The tuner displays the data from the sensor in the Widget View and Graph View tabs.

6. Set the Read Mode to the Synchronized mode. Under the Widget View tab, you can see the touchpad widget sensors highlighted when you touch it.

   Figure 5. Widget view of the CAPSENSE™ Tuner

   

7. You can view the raw count, baseline, difference count for each sensor and also the touchpad position in the Graph View tab. For example, to view the sensor data for a single sensor in Touchpad, select Touchpad_Rx0_Tx0 under Touchpad.

   Figure 6. Graph view of the CAPSENSE™ Tuner

   

8. The Touchpad View tab shows the heat map view and the finger movement can be visualized on the same.

   Figure 7. Touchpad view of the CAPSENSE™ Tuner

   

9. Observe the Widget/Sensor parameters section in the CAPSENSE™ Tuner window. The compensation CDAC values for each touchpad sensor element calculated by the CAPSENSE™ resource is displayed as shown in Figure 7.

10. Verify that the signal to noise ratio (SNR) is greater than 5:1 by following the steps given in Stage 4 Tuning procedure.

    The linearity of the position graph, non-reporting of false touches, and no discontinuity in the line drawing indicate a proper tuning.

11. The Gesture View tab visually represents evaluation and tuning of gestures (from one widget at a time). The gesture view tab is disabled when there are no gesture widgets in the configuration.

    Figure 8. Gesture view of the CAPSENSE™ Tuner

    

12. Gesture Monitor provides visual indication for a detected gesture. Gesture Event History logs the detected gestures information.

    Note: To open the Gesture Monitor window, Select View > Gesture Monitor/Gesture Event History

    Figure 9. Gesture monitor view of CAPSENSE™ Tuner

    

Operation at other voltages

CY8CKIT-040T supports operating voltages of 1.8 V, 3.3 V, and 5 V. Use voltage selection switch available on top of the kit to set the preferred operating voltage and see the setup the VDDA supply voltage and Debug mode section.

This application functionalities are optimally tuned for 1.8 V. However, you can observe the basic functionalities working across other voltages.

It is recommended to tune application for the preferred voltages for better performance.

Tuning procedure

Create custom BSP for your board

1. Create a custom BSP for your board with any device by following the steps given in ModusToolbox™ BSP Assistant user guide. This code example was created for the device "CY8C4046LQI-T452".

2. Open the design.modus file from the {Application root directory}/bsps/TARGET_APP_<BSP-NAME>/config/ folder obtained in the previous step and enable CAPSENSE™ to get the design.cycapsense file. CAPSENSE™ configuration can then be started from scratch as explained below.

The following steps explain the tuning procedure.

Note: See the "Selecting CAPSENSE™ hardware parameters" section in the PSoC™ 4 and PSoC™ 6 MCU CAPSENSE™ design guide to learn about the considerations for selecting each parameter values.

Figure 10. CSX touchpad widget and Gesture tuning flow

Do the following to tune the touchpad widget:

Stage 1: Set initial hardware parameters

Stage 2: Set the sense clock frequency

Stage 3: Obtain crossover point and noise

Stage 4. Fine-tune sensitivity to improve SNR

Stage 5: Tune threshold parameters

Stage 6: Set gesture parameters

Stage 1: Set initial hardware parameters

1. Connect the board to your PC using the provided USB cable through the KitProg3 USB connector.

2. Launch the Device Configurator tool.

   You can launch the Device Configurator in Eclipse IDE for ModusToolbox™ from the Tools section in the IDE Quick panel or in standalone mode from {ModusToolbox™ install directory}/ModusToolbox/tools_{version}/device-configurator/device-configurator. In this case, after opening the application, select File > Open and open the design.modus file of the respective application, which is present in the {Application root directory}/bsps/TARGET_APP_<BSP-NAME>/config/ folder.

3. In the PSoC™ 4000T kit, the touchpad pins are connected to CAPSENSE™ channel (MSCLP 0). Therefore, make sure that you enable CAPSENSE™ channel in the Device Configurator, as shown in Figure 11.

   Figure 11. Enable MSCLP channel in Device Configurator

   

   Save the changes and close the window.

4. Launch the CAPSENSE™ Configurator tool.

   You can launch the CAPSENSE™ Configurator tool in Eclipse IDE for ModusToolbox™ from the 'CAPSENSE™' peripheral setting in Device Configurator or directly from the Tools section in the IDE Quick panel. You can also launch it in standalone mode from {ModusToolbox™ install directory}/ModusToolbox/tools_{version}/capsense-configurator/capsense-configurator. 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}/bsps/TARGET_APP_<BSP-NAME>/config/ folder.

   See the ModusToolbox™ CAPSENSE™ Configurator tool guide for step-by-step instructions on how to configure and launch CAPSENSE™ in ModusToolbox™.

5. In the Basic tab, note that a touchpad Touchpad is configured with CSX RM (Mutual-cap) Sensing mode.

   Figure 12. CAPSENSE™ Configurator - Basic tab

   

6. Do the following in the General tab under the Advanced tab:

   • Select CAPSENSE™ IMO clock frequency as 46 MHz.

   • Set Modulator clock divider to "1" to obtain the maximum available modulator clock frequency as recommended in the PSoC™ 4 and PSoC™ 6 MCU CAPSENSE™ design guide.

     Note: The modulator clock frequency can be set to 46,000 kHz after changing the CAPSENSE™ IMO clock frequency to 46 MHz, because the modulator clock is derived from the CAPSENSE™ IMO clock. In the CAPSENSE™ IMO clock frequency drop-down, select 46 MHz.

   • Number of init sub-conversions is set based on the hint shown when you hover over the edit box. Retain the default value.

   • Because CIC2 filter is enabled, it is recommended to enable IIR filter. Retain the default settings for all filters. You can enable the filters later depending on the signal-to-noise ratio (SNR) requirements mentioned in Stage 4.

     Filters are used to reduce the peak-to-peak noise. Using filters will result in longer scan time.

   Figure 13. CAPSENSE™ Configurator - General settings

   

   Note: Each tab has a Restore Defaults button to restore the parameters of that tab to their default values.

7. Go to the CSX Settings tab and make the following changes:

   • Set Inactive Sensor connection to Ground.

   • Set Number of reported fingers to 2 for two-finger detection.

   Figure 14. CAPSENSE™ Configurator - Advanced CSX settings

   

8. Go to the Widget Details tab. Select Touchpad from the left pane and then set the following:

   • Maximum X-Axis position and Maximum Y-Axis position to 255.

   • Tx clock divider: Retain default value (will be set in Stage 2)

   • Clock source: Direct

   Note: Spread spectrum clock (SSC) or PRS clock can be used as a clock source to deal with EMI/EMC issues.

   • Number of sub-conversions: 25

     25 is a good starting point to ensure a fast scan time and sufficient signal. This value will be adjusted as required in Stage 3.

   • Finger Threshold: 20

     Finger Threshold is initially set to a low value, which allows the Touchpad View to track the finger movement during tuning.

   • Noise Threshold: 10

   • Negative Noise Threshold: 10

   • Hysteresis: 5

   • ON debounce: 10

     These values reduces the influence of baseline on the sensor signal, which helps to get the true difference-count. Retain the default values for the widget threshold parameters; these parameters are set in Stage 5.

   • Enable gestures: True

     Note: Select the Gestures you want to include in your application. In this CE, we are demonstrating the selected gestures shown in Figure 15.

   Figure 15. CAPSENSE™ Configurator - Widget details settings

   

9. Go to the Scan Configuration tab to select the pins, the scan slots, and do the following:

   • Configure the pin for the electrode using the drop-down menu.

   • Configure the scan slot using the Auto-Assign Slots option or each sensor is allotted a scan slot based on the entered slot number.

   • Check the notice list for warning or errors.

   Note: Enable the Notice List in the View menu if it is not visible.

   Figure 16. Scan Configuration tab

   

10. Click Save to apply the settings.

Stage 2: Set the sense clock frequency

The sense clock is derived from the modulator clock using a clock-divider and is used to scan the sensor by driving the CAPSENSE™ switched capacitor circuits. Both the clock source and clock divider are configurable. The sense clock divider should be configured such that the pulse width of the sense clock is long enough to allow the sensor capacitance to charge and discharge completely. This is verified by observing the charging and discharging waveforms of the sensor using an oscilloscope and an active probe. The sensors should be probed close to the electrode and not at the sense pins or the series resistor.

See Figure 17and Figure 18 for waveforms observed on the shield. Figure 17 shows proper charging when the sense clock frequency is correctly tuned. The pulse width is at least 5 Tau, i.e., the voltage is reaching at least 99.3% of the required voltage at the end of each phase. Figure 18 shows incomplete settling (charging/discharging).

Figure 17. Proper charge cycle of a sensor

Figure 18. Improper charge cycle of a sensor

1. Program the board and launch CAPSENSE™ Tuner.

2. See the charging waveform of the sensor as described earlier.

3. If the charging is incomplete, increase the sense clock divider. This can be done in CAPSENSE™ Tuner by selecting the Sensor and editing the Sense Clock Divider parameter in the Widget/Sensor Parameters panel.

Note: The sense clock divider should be divisible by 2. This ensures that both the scan phases have equal durations.

After editing the value, click the Apply to Device button and observe the waveform again. Repeat this until complete settling is observed.

4. Click the Apply to Project button so that the configuration is saved to your project.

   Figure 19. Sense Clock Divider setting

   

5. Repeat this process for all the sensors and the Shield. Each sensor may require a different sense clock divider value to charge/discharge completely. But all the sensors that are in the same scan slot need to have the same sense clock source, sense clock divider, and number of sub-conversions. Therefore, take the largest sense clock divider in a given scan slot and apply it to all the other sensors that share that slot.

Stage 3: Obtain crossover point and noise

1. Program the board.

2. Launch the CAPSENSE™ Tuner to monitor the CAPSENSE™ data and for CAPSENSE™ parameter tuning and SNR measurement.

   See the CAPSENSE™ Tuner guide for step-by-step instructions on how to launch and configure the CAPSENSE™ Tuner in ModusToolbox™ software.

3. Capture the raw counts of each sensor element in the touchpad (as shown in Figure 20) and verify that they are approximately (± 5%) equal to 40% of the MaxCount. See design guide for the MaxCount equation.

   1. Go to the Touchpad View tab and change the Display settings as follows:

      • Data type: RawCount

      • Value type: Current

      • Number of samples: 1000

   Figure 20. Raw counts obtained on the Touchpad View tab in Tuner window

   

4. Capture and note the peak-to-peak noise of each sensor element in the touchpad.

   1. From the Widget Explorer section, select the Touchpad widget.

   2. Go to the Touchpad View tab and change the Display settings as follows:

      • Display mode: Touch Reporting

      • Data type: RawCount

      • Value type: Max-Min

      • Number of Samples: 1000

      Capture the variation in the raw counts for 1000 samples, without placing a finger (which gives the peak-to-peak noise) and note the highest noise.

   Note: Under Widget selection, enable Swap XY-axes for proper visualization of finger movement on the touchpad.

   Figure 21. Noise obtained on the Touchpad View tab in Tuner window

   

   Table 1. Max peak-to-peak noise obtained in CY8CKIT-040T

   Kit	Max peak-to-peak noise
   CY8CKIT-040T	62

   
   

5. A finger (6 mm) should be held on the touchpad in the least touch intensity (LTI) position (at the intersection of four nodes) as shown in Figure 22.

   Figure 22. Least touch intensity (LTI) position

   

   Note: Finger movement during the test can artificially increase the noise level.

   1. Go to the Touchpad View tab and change the Display settings as follows:

      • Display mode: Touch Reporting

      • Data type: DiffCount

      • Value type: Current

   2. Place the finger such that an almost equal signal is obtained in all four intersecting nodes (look at the heat map displayed in the Touchpad View tab as shown in Figure 23).

      Note: The LTI signal is measured at the farthest point of the touchpad from the sensor pin connection, where the sensors have the worst-case RC-time constant.

   Figure 23. LTI position in Touchpad View

   

   LTI Signal = (327 + 336 + 323 + 381)/4 = 341

Stage 4. Fine-tune sensitivity to improve SNR

---

The CAPSENSE™ system may be required to work reliably in adverse conditions such as a noisy environment. The touchpad sensors should be tuned with SNR > 5:1 to avoid triggering false touches and to make sure that all intended touches are registered in these adverse conditions.

Note: For gesture detection, it is recommended to have approximately 10:1 SNR.

1. Ensure that the LTI Signal count is greater than 50 and meets at least 5:1 SNR (using Equation 1).

   In the CAPSENSE™ Tuner window, increase the Number of sub-conversions (located in the Widget/Sensor Parameters section, under Widget Hardware Parameters) by 10 until you achieve this requirement.

   Equation 1: Measuring the SNR

   

   Where,

   • LTI signal is the signal obtained as shown in Figure 23.

   • Pk-Pk noise is the peak-to-peak noise obtained as shown in Figure 21.

   SNR is measured using Equation 1.

   Here, from Figure 21 and Figure 23,

   SNR = 341/62 = 5.5

   Note: Ensure that the Number of sub-conversions (Nsub) does not exceed the max limit and saturate the raw count.

2. Update the number of sub-conversions

   • Update the number of sub-conversions (Nsub) directly in the Widget/Sensor parameters tab of the CAPSENSE™ Tuner.

   • CY8CKIT-040T kit has an in-built CIC2 filter which increases the resolution for the same scan time, see AN234231 - Achieving lowest-power capacitive sensing with PSoC™ 4000T for detailed information on CIC2 filter.

   • Current consumption is directly proportional to number of sub-conversion, therefore, decrease the number of sub-conversions to achieve lower current consumption.

     Note: Number of sub-conversion should be greater than or equal to 8.

3. After changing the Number of sub-conversions, click Apply to Device to send the setting to the device. The change is reflected in the graphs.

Note: The Apply to Device option is enabled only when the Number of sub-conversions is changed.

4. If the SNR condition is not achieved even with the maximum number of sub-conversions, enable filters in the General settings (go to the Advanced tab of the CAPSENSE™ Configurator). This is generally not required for this kit.

Stage 5: Tune threshold parameters

After confirming that your design meets the timing parameters and power requirements, and the SNR is greater than 5:1, set your threshold parameters.

Note: Thresholds are set based on the LTI position, because it is the least valid touch signal that can be obtained.

Set the recommended threshold values for the Touchpad widget using the LTI signal value obtained in Stage 4:

• Finger Threshold: 80% of the LTI signal

• Noise Threshold: Twice the highest noise or 40% of the LTI signal (whichever is greater)

• Negative Noise Threshold: Twice the highest noise or 40% of the LTI signal (whichever is greater)

• Hysteresis

  Do the following:

  1. Place the finger in the LTI position.

  2. Set the Data type to DiffCount and Value type to Max-Min in the Touchpad View tab and click Clear.

  3. Record the max-min count value (Max_Min_count) of the selected 2x2 sensors.

  Figure 24. Obtaining the hysteresis

  
  4. Hysteresis = Max_Min_count/2 = 63/2 = 31

• ON Debounce: 3 (Set to 1 for gesture detection)

• Low Baseline Reset: Default value of 30

• Velocity: Default value of 2500

  Note: For multiple finger detection, if the velocity value is low, two touches at different positions are considered to be two different finger touches. On the other hand, if it is set at a higher value, it is considered to be the same finger moving to a different position.

Table 2. Software tuning parameters obtained for CY8CKIT-040T

Parameter	CY8CKIT-040T kit
Number of Sub-conversions	341
Finger threshold	273
Noise threshold	136
Negative noise threshold	136
Low baseline reset	30
Hysteresis	31
ON debounce	3
Velocity	2500

Stage 6: Set gesture parameters

You can set the gesture parameters directly in the Widget/Sensor Parameters tab of the CAPSENSE™ Tuner and observe the results in the Gesture Monitor/Gesture View.

Note: Click on the parameter to understand the definition and its valid range.

Figure 25. Gesture parameters

In this application gesture parameters have been set for the typical use case, but user can change these parameters as per the need of their application use case.

Apply settings to firmware

1. Click Apply to Device and Apply to Project in the CAPSENSE™ Tuner window to apply the settings to the device and project, respectively. Close the tuner.

Figure 26. Apply to Project

Debugging

You can debug the example to step through the code.

In Eclipse 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.

In other IDEs

Follow the instructions in your preferred IDE.

By default, the debug option is disabled in the device configurator. To enable the debug option, see the Set up VDDA supply and debug mode in Device Configurator section. To achieve low power consumption, it is recommended to disable it.

Design and implementation

The project contains a touchpad widget configured in CSX-RM Sensing mode. See the Tuning procedure section for step-by-step instructions to configure the other settings of the CAPSENSE™ Configurator.

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™ 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 onboard KitProg, which in turn enables reading the CAPSENSE™ raw data by the CAPSENSE™ Tuner; see Figure 29.

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 successful tuning of the touchpad is indicated by the RGB LED in the evaluation kit; the LED1 brightness increases when finger is moved from bottom to up and LED3 brightness increases when finger is moved from left to right on the touchpad.

The MOSI (master output slave input) pin of the SPI slave peripheral is used to transfer data to the three serially connected LEDs for controlling color, brightness, and ON or OFF operation. The three LEDs form a daisy-chain connection and the communication happens over the serial interface to create an RGB configuration. The LED accepts a 32-bit input code, with three bytes for red, green, and blue color, five bits for global brightness, and three blank ‘1’ bits. See the LED datasheet for more details.

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

1. Open Device Configurator from the Quick panel.

2. Go to the Systems tab, select the Power resource, and set the VDDA value under Operating Conditions as shown in Figure 28.

Figure 27. Setting the VDDA supply in the system tab of Device Configurator

3. By default, the debug mode is disabled for this application to reduce power consumption. Enable the debug mode to enable the SWD pins as shown in Figure 29:

   Figure 28. Enable Debug mode in the System tab of Device Configurator

   

Resources and settings

See the Operation section for step-by-step instructions to configure the CAPSENSE™ Configurator.

Figure 29. Device Configurator - EZI2C peripheral parameters

Figure 30. SPI settings

Table 3. Application resources

Resource	Alias/object	Purpose
SCB (I2C) (PDL)	CYBSP_EZI2C	EZI2C slave driver to communicate with CAPSENSE™ Tuner GUI
CAPSENSE™	CYBSP_MSCLP0	CAPSENSE™ driver to interact with the MSCLP hardware and interface the CAPSENSE™ sensors
Digital pin	CYBSP_USER_LED	To visualise the touchpad response

Firmware flow

Figure 31. Firmware flowchart

Related resources

Resources	Links
Application notes	AN79953 – Getting started with PSoC™ 4 AN85951 – PSoC™ 4 and PSoC™ 6 MCU CAPSENSE™ design guide AN234231 - Achieving lowest-power capacitive sensing with PSoC™ 4000T
Code examples	Using ModusToolbox™ on GitHub Using PSoC™ Creator
Device documentation	PSoC™ 4 datasheets PSoC™ 4 technical reference manuals
Development kits	Select your kits from the Evaluation board finder
Libraries on GitHub	mtb-hal-cat2 – Hardware Abstraction Layer (HAL) library
Middleware on GitHub	capsense – CAPSENSE™ library and documents
Tools	Eclipse IDE for ModusToolbox™ – ModusToolbox™ – ModusToolbox™ software is a collection of easy-to-use libraries and tools enabling rapid development with Infineon MCUs for applications ranging from wireless and cloud-connected systems, edge AI/ML, embedded sense and control, to wired USB connectivity using PSoC™ Industrial/IoT MCUs, AIROC™ Wi-Fi and Bluetooth® connectivity devices, XMC™ Industrial MCUs, and EZ-USB™/EZ-PD™ wired connectivity controllers. ModusToolbox™ incorporates a comprehensive set of BSPs, HAL, libraries, configuration tools, and provides support for industry-standard IDEs to fast-track your embedded application development. PSoC™ Creator – IDE for PSoC™ and FM0+ MCU development

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.

The Bluetooth® word mark and logos are registered trademarks owned by Bluetooth SIG, Inc., and any use of such marks by Infineon is under license.

Document history

Document title: CE235339 - PSoC™ 4: MSCLP multitouch mutual-capacitance touchpad tuning

Version	Description of change
1.0.0	New code example This version is not backward compatible with ModusToolbox™ software v2.4
1.0.1	Project dependency update
1.1.0	Minor folder structure changes that doesn't break backward compatibility.
1.2.0	Minor README and configuration update.
2.0.0	Major update to support ModusToolbox™ software v3.1 This version is not backward compatible with ModusToolbox™ software v3.0
2.1.0	Gesture demonstration added on a mutual-capacitance-based touchpad widget
2.1.1	Minor configuration and readme update
3.0.0	Major update to support ModusToolbox™ v3.2 and CAPSENSE™ Middleware v5.0. This version is not backward compatible with previous versions of ModusToolbox™ software.

All other trademarks or registered trademarks referenced herein are the property of their respective owners.

The Bluetooth® word mark and logos are registered trademarks owned by Bluetooth SIG, Inc., and any use of such marks by Infineon is under license.

---

© Cypress Semiconductor Corporation, 2022-2023. This document is the property of Cypress Semiconductor Corporation, an Infineon Technologies company, and its affiliates ("Cypress"). This document, including any software or firmware included or referenced in this document ("Software"), is owned by Cypress under the intellectual property laws and treaties of the United States and other countries worldwide. Cypress reserves all rights under such laws and treaties and does not, except as specifically stated in this paragraph, grant any license under its patents, copyrights, trademarks, or other intellectual property rights. If the Software is not accompanied by a license agreement and you do not otherwise have a written agreement with Cypress governing the use of the Software, then Cypress hereby grants you a personal, non-exclusive, nontransferable license (without the right to sublicense) (1) under its copyright rights in the Software (a) for Software provided in source code form, to modify and reproduce the Software solely for use with Cypress hardware products, only internally within your organization, and (b) to distribute the Software in binary code form externally to end users (either directly or indirectly through resellers and distributors), solely for use on Cypress hardware product units, and (2) under those claims of Cypress’s patents that are infringed by the Software (as provided by Cypress, unmodified) to make, use, distribute, and import the Software solely for use with Cypress hardware products. Any other use, reproduction, modification, translation, or compilation of the Software is prohibited.
TO THE EXTENT PERMITTED BY APPLICABLE LAW, CYPRESS MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARD TO THIS DOCUMENT OR ANY SOFTWARE OR ACCOMPANYING HARDWARE, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. No computing device can be absolutely secure. Therefore, despite security measures implemented in Cypress hardware or software products, Cypress shall have no liability arising out of any security breach, such as unauthorized access to or use of a Cypress product. CYPRESS DOES NOT REPRESENT, WARRANT, OR GUARANTEE THAT CYPRESS PRODUCTS, OR SYSTEMS CREATED USING CYPRESS PRODUCTS, WILL BE FREE FROM CORRUPTION, ATTACK, VIRUSES, INTERFERENCE, HACKING, DATA LOSS OR THEFT, OR OTHER SECURITY INTRUSION (collectively, "Security Breach"). Cypress disclaims any liability relating to any Security Breach, and you shall and hereby do release Cypress from any claim, damage, or other liability arising from any Security Breach. In addition, the products described in these materials may contain design defects or errors known as errata which may cause the product to deviate from published specifications. To the extent permitted by applicable law, Cypress reserves the right to make changes to this document without further notice. Cypress does not assume any liability arising out of the application or use of any product or circuit described in this document. Any information provided in this document, including any sample design information or programming code, is provided only for reference purposes. It is the responsibility of the user of this document to properly design, program, and test the functionality and safety of any application made of this information and any resulting product. "High-Risk Device" means any device or system whose failure could cause personal injury, death, or property damage. Examples of High-Risk Devices are weapons, nuclear installations, surgical implants, and other medical devices. "Critical Component" means any component of a High-Risk Device whose failure to perform can be reasonably expected to cause, directly or indirectly, the failure of the High-Risk Device, or to affect its safety or effectiveness. Cypress is not liable, in whole or in part, and you shall and hereby do release Cypress from any claim, damage, or other liability arising from any use of a Cypress product as a Critical Component in a High-Risk Device. You shall indemnify and hold Cypress, including its affiliates, and its directors, officers, employees, agents, distributors, and assigns harmless from and against all claims, costs, damages, and expenses, arising out of any claim, including claims for product liability, personal injury or death, or property damage arising from any use of a Cypress product as a Critical Component in a High-Risk Device. Cypress products are not intended or authorized for use as a Critical Component in any High-Risk Device except to the limited extent that (i) Cypress's published data sheet for the product explicitly states Cypress has qualified the product for use in a specific High-Risk Device, or (ii) Cypress has given you advance written authorization to use the product as a Critical Component in the specific High-Risk Device and you have signed a separate indemnification agreement.
Cypress, the Cypress logo, and combinations thereof, ModusToolbox, PSoC, CAPSENSE, EZ-USB, F-RAM, and TRAVEO are trademarks or registered trademarks of Cypress or a subsidiary of Cypress in the United States or in other countries. For a more complete list of Cypress trademarks, visit www.infineon.com. Other names and brands may be claimed as property of their respective owners.