README.md

# 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.](https://github.com/Infineon/mtb-example-psoc4-msclp-csx-touchpad)

[Provide feedback on this code example.](https://cypress.co1.qualtrics.com/jfe/form/SV_1NTns53sK2yiljn?Q_EED=eyJVbmlxdWUgRG9jIElkIjoiQ0UyMzUzMzkiLCJTcGVjIE51bWJlciI6IjAwMi0zNTMzOSIsIkRvYyBUaXRsZSI6IlBTb0MmdHJhZGU7IDQ6IE1TQ0xQIG11bHRpdG91Y2ggbXV0dWFsLWNhcGFjaXRhbmNlIHRvdWNocGFkIHR1bmluZyIsInJpZCI6Inlhc2h2aSIsIkRvYyB2ZXJzaW9uIjoiMy4wLjAiLCJEb2MgTGFuZ3VhZ2UiOiJFbmdsaXNoIiwiRG9jIERpdmlzaW9uIjoiTUNEIiwiRG9jIEJVIjoiSUNXIiwiRG9jIEZhbWlseSI6IlBTT0MifQ==)


## Requirements

- [ModusToolbox™](https://www.infineon.com/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](https://www.infineon.com/cms/en/product/microcontroller/32-bit-psoc-arm-cortex-microcontroller/psoc-4-32-bit-arm-cortex-m0-mcu/psoc-4000/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](https://www.infineon.com/CY8CKIT-040T) (`CY8CKIT-040T`) – Default `TARGET`




## Hardware setup

This example uses the board's default configuration. See the [kit user guide](https://www.infineon.com/002-34870) to ensure that the board is configured correctly to use VDDA at 1.8 V.

> **Note:** The PSoC™ 4 kits (except [CY8CKIT-040T](https://www.infineon.com/CY8CKIT-040T) and [CY8CKIT-041S-MAX](https://www.infineon.com/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](https://github.com/Infineon/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](https://www.infineon.com/ModusToolboxInstallguide) 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.

<details><summary><b>Use Project Creator GUI</b></summary>

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](https://www.infineon.com/ModusToolboxProjectCreator) (locally available at *{ModusToolbox&trade; 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](#supported-kits-make-variable-target).

   > **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.

</details>

<details><summary><b>Use Project Creator CLI</b></summary>

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&trade; 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&trade; installation instead of a standard Windows command-line application. This shell provides access to all ModusToolbox&trade; 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&trade; MSCLP mutual capacitance touchpad tuning](https://github.com/Infineon/mtb-example-psoc4-msclp-mutual-capacitance-touchpad)" 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 <id> field of the [BSP](https://github.com/Infineon?q=bsp-manifest&type=&language=&sort=) manifest | Required
`--app-id`   | Defined in the <id> field of the [CE](https://github.com/Infineon?q=ce-manifest&type=&language=&sort=) 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&trade; tools package user guide](https://www.infineon.com/ModusToolboxUserGuide) (locally available at {ModusToolbox&trade; install directory}/docs_{version}/mtb_user_guide.pdf).

</details>



### Open the project

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


<details><summary><b>Eclipse IDE</b></summary>

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&trade; user guide](https://www.infineon.com/MTBEclipseIDEUserGuide) (locally available at *{ModusToolbox&trade; install directory}/docs_{version}/mt_ide_user_guide.pdf*).

</details>


<details><summary><b>Visual Studio (VS) Code</b></summary>

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&trade; user guide](https://www.infineon.com/MTBVSCodeUserGuide) (locally available at *{ModusToolbox&trade; install directory}/docs_{version}/mt_vscode_user_guide.pdf*).

</details>


<details><summary><b>Keil µVision</b></summary>

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

For more details, see the [Keil µVision for ModusToolbox&trade; user guide](https://www.infineon.com/MTBuVisionUserGuide) (locally available at *{ModusToolbox&trade; install directory}/docs_{version}/mt_uvision_user_guide.pdf*).

</details>


<details><summary><b>IAR Embedded Workbench</b></summary>

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&trade; user guide](https://www.infineon.com/MTBIARUserGuide) (locally available at *{ModusToolbox&trade; install directory}/docs_{version}/mt_iar_user_guide.pdf*).

</details>


<details><summary><b>Command line</b></summary>

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&trade; tools package user guide](https://www.infineon.com/ModusToolboxUserGuide) (locally available at *{ModusToolbox&trade; install directory}/docs_{version}/mtb_user_guide.pdf*).

</details>


## 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](https://www.infineon.com/CY8CKIT-040T) kit with the PC**

   <img src="images/kit_connection.png" alt="" width="250" />

2. Program the board using one of the following:

   <details><summary><b>Using Eclipse IDE </b></summary>

      1. Select the application Project in the Project Explorer.

      2. In the **Quick Panel**, scroll down, and click **\<Application Name> Program (KitProg3_MiniProg4)**.
   </details>

   <details><summary><b>Using CLI</b></summary>

     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
      ```
   </details>

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.

   ``` c
   "Error: Error connecting Dp: Cannot read IDR"
   ```

4. To test the application:
   - Slide your finger over the CAPSENSE&trade; 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&trade; data using the CAPSENSE&trade; Tuner application:

    **Monitor data using CAPSENSE&trade; Tuner**

    1. Open CAPSENSE&trade; Tuner from the tools section in the IDE **Quick Panel**.

        You can also run the CAPSENSE&trade; Tuner application in standalone mode from *{ModusToolbox&trade; 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&trade; user guide](https://www.infineon.com/ModusToolboxUserGuide) (locally available at *{ModusToolbox&trade; install directory}/docs_{version}/mtb_user_guide.pdf*) for options to open the CAPSENSE&trade; 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](https://github.com/Infineon/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**

        <img src="images/tuner-comm-setup.png" alt="" width="600" />

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

       **Figure 3. Establish a connection**

        <img src="images/tuner-connect.png" alt="" width="430" />

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

         **Figure 4. Start tuner communication**

         <img src="images/tuner-start.png" alt="" width="430" />

         The **Widget/Sensor parameters** tab gets updated with the parameters configured in the **CAPSENSE&trade; 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&trade; Tuner**

     <img src="images/widget-view.png" alt="" width="600"/>

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&trade; Tuner**

   <img src="images/graph_view.png" alt="" width="600"/>

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&trade; Tuner**

   <img src="images/touchpad-view-tuner.png" alt="" width="600"/>

9. Observe the **Widget/Sensor parameters** section in the CAPSENSE&trade; Tuner window. The compensation CDAC values for each touchpad sensor element calculated by the CAPSENSE&trade; 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**](#stage-4-fine-tune-sensitivity-to-improve-snr) [Tuning procedure](#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&trade; Tuner**

    <img src="images/gesture-view-tuner.png" alt="" width="600"/>

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&trade; Tuner**

      <img src="images/monitor-view-tuner.png" alt="" width="600"/>

## Operation at other voltages

[CY8CKIT-040T](https://www.infineon.com/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](#set-up-the-vdda-supply-voltage-and-debug-mode-in-device-configurator) 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.
      
</details>

<br>

## Tuning procedure

<details><summary><b> Create custom BSP for your board </b></summary>

1. Create a custom BSP for your board with any device by following the steps given in [ModusToolbox&trade; BSP Assistant user guide](https://www.infineon.com/ModusToolboxBSPAssistant). 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&trade; to get the *design.cycapsense* file. CAPSENSE&trade; configuration can then be started from scratch as explained below.
</details>

The following steps explain the tuning procedure. 

> **Note:** See the "Selecting CAPSENSE&trade; hardware parameters" section in the [PSoC&trade; 4 and PSoC&trade; 6 MCU CAPSENSE&trade; design guide](https://www.infineon.com/AN85951) to learn about the considerations for selecting each parameter values.

**Figure 10. CSX touchpad widget and Gesture tuning flow**

<img src="images/flowchart_for_tuning.png" alt="" width="300" />

Do the following to tune the touchpad widget:

[Stage 1: Set initial hardware parameters](#stage-1-set-initial-hardware-parameters)

[Stage 2: Set the sense clock frequency](#stage-2-set-the-sense-clock-frequency)

[Stage 3: Obtain crossover point and noise](#stage-3-obtain-crossover-point-and-noise)

[Stage 4. Fine-tune sensitivity to improve SNR](#stage-4-fine-tune-sensitivity-to-improve-snr)

[Stage 5: Tune threshold parameters](#stage-5-tune-threshold-parameters)

[Stage 6: Set gesture 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&trade; from the **Tools** section in the IDE Quick panel or in standalone mode from *{ModusToolbox&trade; 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&trade; 4000T kit](https://www.infineon.com/CY8CKIT-040T), the touchpad pins are connected to CAPSENSE&trade; channel (MSCLP 0). Therefore, make sure that you enable CAPSENSE&trade; channel in the Device Configurator, as shown in **Figure 11**.

   **Figure 11. Enable MSCLP channel in Device Configurator**

   <img src="images/device-configurator-channel.png" alt="" width="600"/>

      Save the changes and close the window.

4. Launch the CAPSENSE&trade; Configurator tool.
   
   You can launch the CAPSENSE&trade; Configurator tool in Eclipse IDE for ModusToolbox&trade; from the 'CAPSENSE&trade;' 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&trade; 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&trade; CAPSENSE&trade; Configurator tool guide](https://www.infineon.com/ModusToolboxCapSenseConfig) for step-by-step instructions on how to configure and launch CAPSENSE&trade; in ModusToolbox&trade;. 

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

   **Figure 12. CAPSENSE&trade; Configurator - Basic tab**

   <img src="images/capsense_basictab.png" alt="" width="600"/>

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

   - Select **CAPSENSE&trade; 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&trade; 4 and PSoC&trade; 6 MCU CAPSENSE&trade; design guide](https://documentation.infineon.com/html/psoc6/epf1667481159393.html).

      > **Note:** The modulator clock frequency can be set to 46,000 kHz after changing the CAPSENSE&trade; IMO clock frequency to 46 MHz, because the modulator clock is derived from the CAPSENSE&trade; IMO clock. In the **CAPSENSE&trade; 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**](#stage-4-fine-tune-sensitivity-to-improve-snr).
      
      Filters are used to reduce the peak-to-peak noise. Using filters will result in longer scan time.

   **Figure 13. CAPSENSE&trade; Configurator - General settings**

   <img src="images/adv_general.png" alt="" width="600"/>

   > **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&trade; Configurator - Advanced CSX settings**

   <img src="images/adv_csx.png" alt="" width="600"/>

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**](#stage-2-set-the-sense-clock-frequency))

   - **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**](#stage-3-obtain-crossover-point-and-noise). 

   - **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**](#stage-5-tune-threshold-parameters).
   
   - **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&trade; Configurator - Widget details settings**

   <img src="images/adv_widget_detail.png" alt="" width="600" />

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**

   <img src="images/scan-config.png" alt="" width="600"/>

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&trade; 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 17**and **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**

<img src="images/csdrm-waveform.png" alt="Figure 17" width="600"/>



**Figure 18. Improper charge cycle of a sensor**

<img src="images/csdrm-waveform-improper.png" alt="Figure 18" width="600"/>

1. Program the board and launch CAPSENSE&trade; 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&trade; 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**

   <img src="images/sense_clock_divider_setting.png" alt="Figure 19" width="300" />
   

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&trade; Tuner to monitor the CAPSENSE&trade; data and for CAPSENSE&trade; parameter tuning and SNR measurement.

   See the [CAPSENSE&trade; Tuner guide](https://www.infineon.com/ModusToolboxCapSenseTuner) for step-by-step instructions on how to launch and configure the CAPSENSE&trade; Tuner in ModusToolbox&trade; 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](https://www.infineon.com/AN85951) 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**

     <img src="images/touchpad-view-rc.png" alt="" width="600"/>

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**

      <img src="images/touchpad-view-noise.png" alt="" width="600"/>

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

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

      <br>

7. 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**

   <img src="images/lti-position.png" alt="" width="300" />

   > **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**

      <img src="images/touchpad-view-lti.png" alt="" width="600"/>

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


### Stage 4. Fine-tune sensitivity to improve SNR
----------------------

The CAPSENSE&trade; 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&trade; 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**

   ![](images/snr-equation.png)

   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&trade; 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&trade; 4000T](https://www.infineon.com/AN234231) 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&trade; 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**](#stage-4-fine-tune-sensitivity-to-improve-snr):

   - **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**

      <img src="images/touchpad-view-hys.png" alt="" width="600" />

      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 

<br>

### Stage 6: Set gesture parameters

You can set the gesture parameters directly in the **Widget/Sensor Parameters** tab of the CAPSENSE&trade; 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**

   <img src="images/gesture_parameters.png" alt="" width="300" />

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&trade; Tuner window to apply the settings to the device and project, respectively. Close the tuner.

  **Figure 26. Apply to Project**

   <img src="images/apply_to_project.png" alt="" width="600" />



## Debugging

You can debug the example to step through the code.


<details><summary><b>In Eclipse IDE</b></summary>

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&trade; user guide](https://www.infineon.com/MTBEclipseIDEUserGuide).

</details>

<details><summary><b>In other IDEs</b></summary>

Follow the instructions in your preferred IDE.</details>

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](#set-up-the-vdda-supply-voltage-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](#tuning-procedure) section for step-by-step instructions to configure the other settings of the **CAPSENSE&trade; Configurator**.

The project uses the [CAPSENSE&trade; middleware](https://github.com/Infineon/capsense) (see ModusToolbox&trade; user guide for more details on selecting a middleware). See [AN85951 – PSoC&trade; 4 and PSoC&trade; 6 MCU CAPSENSE&trade; design guide](https://www.infineon.com/AN85951) for more details on CAPSENSE&trade; features and usage.

The [ModusToolbox&trade;](https://www.infineon.com/modustoolbox) provides a GUI-based Tuner application for debugging and tuning the CAPSENSE&trade; system. The CAPSENSE&trade; 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&trade; raw data by the CAPSENSE&trade; Tuner; see **Figure 29**.

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

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](https://media.digikey.com/pdf/Data%20Sheets/Everlight%20PDFs/12-23C_RSGHBHW-5V01_2C_Rev4_12-17-18.pdf) 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**

   <img src="images/vdda-settings.png" alt="" width="600"/>

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**

   <img src="images/enable_debug.png" alt="Figure 32" width="600"/>

### Resources and settings

See the [Operation](#operation) section for step-by-step instructions to configure the CAPSENSE&trade; Configurator.

**Figure 29. Device Configurator - EZI2C peripheral parameters**

<img src="images/ezi2c_config.png" alt="" width="600"/>

**Figure 30. SPI settings**

<img src="images/spi-settings.png" alt="" width="600"/>

**Table 3. Application resources**

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

 <br>

### Firmware flow

**Figure 31. Firmware flowchart**

<img src="images/firmware_flow.png" alt="" width="300"/>

## Related resources

Resources  | Links
-----------|----------------------------------
Application notes  | [AN79953](https://www.infineon.com/AN79953) – Getting started with PSoC&trade; 4 <br> [AN85951](https://www.infineon.com/AN85951) – PSoC&trade; 4 and PSoC&trade; 6 MCU CAPSENSE&trade; design guide <br> [AN234231](https://www.infineon.com/AN234231) - Achieving lowest-power capacitive sensing with PSoC&trade; 4000T
Code examples | [Using ModusToolbox&trade;](https://github.com/Infineon/Code-Examples-for-ModusToolbox-Software) on GitHub <br> [Using PSoC&trade; Creator](https://www.infineon.com/cms/en/design-support/software/code-examples/psoc-3-4-5-code-examples-for-psoc-creator)
Device documentation | [PSoC&trade; 4 datasheets](https://www.infineon.com/cms/en/search.html?intc=searchkwr-return#!view=downloads&term=psoc%204&doc_group=Data%20Sheet) <br>[PSoC&trade; 4 technical reference manuals](https://www.infineon.com/cms/en/search.html#!term=psoc%204%20technical%20reference%20manual&view=all)
Development kits | Select your kits from the [Evaluation board finder](https://www.infineon.com/cms/en/design-support/finder-selection-tools/product-finder/evaluation-board)
Libraries on GitHub  | [mtb-hal-cat2](https://github.com/Infineon/mtb-hal-cat2) – Hardware Abstraction Layer (HAL) library
Middleware on GitHub | [capsense](https://github.com/Infineon/capsense) – CAPSENSE&trade; library and documents <br>
Tools | [Eclipse IDE for ModusToolbox&trade;](https://www.infineon.com/modustoolbox) – [ModusToolbox&trade;](https://www.infineon.com/modustoolbox) – ModusToolbox&trade; 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&trade; Industrial/IoT MCUs, AIROC&trade; Wi-Fi and Bluetooth&reg; connectivity devices, XMC&trade; Industrial MCUs, and EZ-USB&trade;/EZ-PD&trade; wired connectivity controllers. ModusToolbox&trade; incorporates a comprehensive set of BSPs, HAL, libraries, configuration tools, and provides support for industry-standard IDEs to fast-track your embedded application development. <br> [PSoC&trade; Creator](https://www.infineon.com/cms/en/design-support/tools/sdk/psoc-software/psoc-creator/) – IDE for PSoC&trade; and FM0+ MCU development

<br>



## Other resources

Infineon provides a wealth of data at [www.infineon.com](https://www.infineon.com) to help you select the right device, and quickly and effectively integrate it into your design.

The Bluetooth&reg; 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&trade; 4: MSCLP multitouch mutual-capacitance touchpad tuning*

 Version | Description of change
 ------- | ---------------------
 1.0.0   | New code example <br> This version is not backward compatible with ModusToolbox&trade; 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&trade; software v3.1 <br> This version is not backward compatible with ModusToolbox&trade; 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&trade; v3.2 and CAPSENSE&trade; Middleware v5.0. This version is not backward compatible with previous versions of ModusToolbox&trade; software.
<br>

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

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

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