Skip to content
Permalink
d62d5dbd33
Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?

mtb-example-psoc4-msclp-low-power-csx-button/README.md

Go to file
 
 
Cannot retrieve contributors at this time
PSoC™ 4: MSCLP low-power mutual-capacitance button Requirements Supported toolchains (make variable 'TOOLCHAIN') Supported kits (make variable 'TARGET') Hardware setup Software setup Using the code example Create the project Open the project Operation Operation at other voltages Measure current at different power modes Table 1. Measured current for different modes Tuning procedure Stage 1: Set the initial hardware parameters Stage 2: Set the sense clock frequency Stage 3: Fine-tune for required SNR and refresh rate Stage 4: Tune the threshold parameters Process time measurement Scan time Measurement Debugging Design and implementation Set up the VDDA supply voltage and Debug mode in Device Configurator Resources and settings Firmware flow Related resources Other resources Document history
893 lines (498 sloc) 49.1 KB
Raw Blame

PSoC™ 4: MSCLP low-power mutual-capacitance button

This code example demonstrates how to use the CAPSENSE™ middleware to detect a finger touch on a mutual-capacitance-based button widget in PSoC™ 4000T device with a multi-sense converter low-power (MSCLP) CAPSENSE™ block.

In addition, this code example also explains how to manually tune the mutual-capacitance-based button for optimum performance with respect to parameters such as reliability, power consumption, and response time using the CSX-RM sensing technique and CAPSENSE™ Tuner GUI. Here, 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

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')

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 5 V.

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 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.

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

    Note: 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 "MSCLP low-power CSX button tuning" application with the desired name "MSCLPMutualCapButtonTuning" configured for the CY8CPROTO-040T BSP into the specified working directory, C:/mtb_projects:

project-creator-cli --board-id CY8CPROTO-040T --app-id mtb-example-psoc4-msclp-low-power-csx-button --user-app-name MSCLPMutualCapButtonTuning --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 the Project Creator tool is opened 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 USB cable through the KitProg3 USB connector as shown in Figure 1.

    Figure 1. Connecting the CY8CPROTO-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).

    In other IDEs

    Follow the instructions in your preferred IDE.

    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 TOOLCHAIN=<toolchain>

    Example:

    make program TOOLCHAIN=GCC_ARM

  3. After programming, the application starts automatically.

    Note: After programming, you see the following error message if Debug mode is disabled. Ignore the error or enable the Debug mode to resolve this error.

    "Error: Error connecting Dp: Cannot read IDR"

  4. To test the application, place your finger over the CAPSENSE™ button and notice that the LED2 turns ON when touched and turns OFF when the finger is lifted.

  5. 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 {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). 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, select the I2C checkbox under KitProg3 and configure as shown in Figure 2.

      • 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 as shown in Figure 3.

      Figure 3. Establish 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 Synchronized mode. Navigate to the Widget View tab, and you can see the Button0 widget highlighted in blue when you touch it as shown in Figure 5.

      Figure 5. Widget View of the CAPSENSE™ Tuner


    7. You can view the raw count, baseline, difference count, and status for each sensor in the Graph View tab. For example, to view the sensor data for Button0, select Button0_Rx0 under Button0.

      Figure 6. Graph View for the CAPSENSE™ Tuner


    8. Observe the Widget/Sensor parameters section in the CAPSENSE™ Tuner window as shown in Figure 6.

    9. Switch to the SNR Measurement tab for measuring the SNR, verify that the SNR is greater than 5:1 and the signal count is above 50, select the Button0 and Button0_Rx0 sensors, and then click Acquire Noise as shown in Figure 7.

      Figure 7. CAPSENSE™ Tuner – SNR measurement: Acquire noise


    10. Once the noise is acquired, place the metal finger (6 mm finger is used in this example) at a position on the button and then click Acquire Signal. Ensure that the metal finger remains on the button as long as the signal acquisition is in progress. Observe that the SNR is above 5:1 and the signal count is above 50.

      The calculated SNR on this button is displayed as shown in Figure 8. Based on your end- system design, test the signal with a finger that matches the size of your normal use case. Typically, finger-size targets are ~4 to 8 mm. Consider testing with smaller sizes that should be rejected by the system to ensure that they do not reach the finger threshold.

      Figure 8. CAPSENSE™ Tuner - SNR measurement: Acquire signal


      Note : Refer to the PSoC™ 4: MSCLP low-power CSD button to observe these power state transitions, indicated by changing the blinking rate of a LED.


Operation at other voltages

CY8CPROTO-040T supports operating voltages of 1.8 V, 3.3 V, and 5 V. Refer to the Kit user guide to set the preferred operating voltage and refer to section setup the VDDA supply voltage and Debug mode.

This application's functionalities are optimally tuned for 5 V. However, basic functionalities works on other voltages.

For better performance, tune the application according to the preferred voltages.

Measure current at different power modes

See the code example CE238817 that describes the steps of current measurement at different power modes.

Table 1. Measured current for different modes

Power mode Refresh rate (Hz) Current consumption (µA)
Active 128 66
Active low-refresh rate
(ALR)		 32 18
Wake-on-Touch
(WoT)		 16 3.0

Note : The above WoT current was measured on a kit having Deep Sleep current of 1.7 µA. If the kit has a Deep Sleep current of 2.5 µA (typical), the WoT current is expected to be ~4.4 µA.

Tuning procedure

Create a custom BSP for your board

  1. Create a custom BSP for your board having 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 as shown in Figure 9.

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

Figure 9. CSD button widget tuning flow

Do the following to tune the button widget:

Stage 1: Set the 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.

    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 button pin is connected to CAPSENSE™ channel (MSCLP 0). Therefore, enable CAPSENSE™ channel in the device configurator as shown in Figure 10.

    Figure 10. Enable MSCLP channels 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 the 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 the button widget 'Button0' is configured as a CSX-RM (mutual-cap) as shown in Figure 11.

    Figure 11. CAPSENSE™ Configurator - Basic tab


  6. Go to General > Advanced tab and do the following as shown in Figure 12.

    1. Select CAPSENSE™ IMO Clock frequency as 46 MHz.

    2. Set the Modulator clock divider to 1 to obtain the maximum available modulator clock frequency.

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

    4. Use Wake-on-Touch settings to set the refresh rate and frame timeout while in the lowest-power mode (Wake-on-Touch mode). Set Wake-on-Touch scan interval (µs) based on the required low-power state scan refresh rate. For example, to get a 16 Hz refresh rate, set the value to 62500.

    5. Set the Number of frames in Wake-on-Touch as the maximum number of frames to be scanned in WoT mode, if there is no touch detected. This determines the maximum time the device will be kept in the lowest-power mode if there is no user activity. Calculate the maximum time by multiplying this parameter with the Wake-on-Touch scan interval (µs) value.

      For example, to get 10 seconds as the maximum time in WoT mode, set the Number of frames in Wake-on-Touch to 160 for the scan interval set as 62500 µs.

      Note: For tuning low-power widgets, the Number of frames in Wake-on-Touch must be less than the Maximum number of raw counts in SRAM based on the number of sensors in WoT mode as follows:

      Table 2. Maximum number of raw counts in SRAM

      Number of low
      power widgets      		 Maximum number of
      raw counts in SRAM
      1 245
      2 117
      3 74
      4 53
      5 40
      6 31
      7 25
      8 21

      Figure 12. CAPSENSE™ Configurator – General settings


    6. Retain the default settings for all regular and low-power widget filters. You can enable or update the filters later depending on the SNR requirements in Stage 3: Fine-tune for required SNR and refresh rate.

      Filters reduce the peak-to-peak noise, and using software filters results in a higher scan time.

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

    7. Go to the CSD and CSX settings tab and make the following changes as shown in Figure 13 and Figure 14.

      Table 3. CSD and CSX Parameters

      Parameters CSD CSX
      Inactive sensor connection Shield Ground
      Shield mode Active NA
      Total shield count 9 NA
      Raw count calibration level 70 40

      Raw count calibration level(%) helps in achieving the required CDAC calibration levels (85% of maximum count by default) for all sensors in the widget, while maintaining the same sensitivity across the sensor elements. This can be reduced, if the application reaches the saturation level on a touch event.

      Figure 13. CAPSENSE™ Configurator - Advanced CSD settings

      Figure 14. CAPSENSE™ Configurator - Advanced CSX settings

    8. Go to Advanced > Widget Details tab. Select Button0 from the left pane, and then set the following as shown in Figure 15.

      • Sense 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: 60

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

      • Finger threshold: 20

      • Noise threshold: 10

      • Negative noise threshold: 10

      • Low-baseline reset: 30

      • Hysteresis: 5

      • ON debounce: 3

        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 4.

        Figure 15. CAPSENSE™ Configurator - Widget Details tab


    9. Go to the Scan Configuration tab to select the pins, scan slots, and then do the following as shown in Figure 16.

      • 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 the 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 minimum pulse width is 5Tau, i.e., the voltage is reaching minimum 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 21

    Figure 18. Improper charge cycle of a sensor

    Figure 22

    1. Program the board and launch thev CAPSENSE™ Tuner.

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

    3. If the charging is incomplete, increase the Sense clock divider. Do this in CAPSENSE™ Tuner by selecting the sensor and editing the Sense clock divider parameter in the Widget/Sensor Parameters panel as shown in Figure 19.

      Note: The sense clock divider should be divisible by 2. This ensures that two 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 to save the configuration 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 should 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 the slot.

    Stage 3: Fine-tune for required SNR and refresh rate

    To ensure reliable operation, the sensor should be tuned to have a minimum SNR of 5:1 and a minimum signal of 50. The sensitivity can be increased by increasing the number of sub-conversions and the noise can be decreased by enabling filters.

    Note: If the sensor raw count saturates (equals Max Raw count) on touch, reduce the Raw count calibration level(%). which helps in avoiding saturation.

    The steps for optimizing these parameters are as follows:

    1. Measure the SNR as mentioned in the Operation section.

    2. If the SNR is less than 5:1, increase the number of sub-conversions. Edit the number of sub-conversions (Nsub) directly in the Widget/Sensor parameters tab of the CAPSENSE™ Tuner.

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

    3. Load the parameters to the device and measure SNR as mentioned in Steps 10 and 11 in the Operation section.

      Repeat steps 1 to 3 until the following conditions are met:

      • Measured SNR from the previous stage is greater than 5:1
      • Signal count is greater than 50

    4. If the system is very noisy (>40% of signal), enable filters.

      This example has the CIC2 filter enabled, which increases the resolution for the same scan time. See AN234231 - Achieving lowest-power capacitive sensing with PSoC™ 4000T for detailed information on the CIC2 filter. Whenever CIC2 filter is enabled, it is recommended to enable the IIR filter for optimal noise reduction. Therefore, this example has the IIR filter enabled as well.

      1. Open CAPSENSE™ Configurator from ModusToolbox™ Quick Panel and select the appropriate filter as shown in Figure 20.

        Figure 20. Filter settings in CAPSENSE™ Configurator


      2. Enable the filter based on the type of noise in your system. See AN85951 – PSoC™ 4 and PSoC™ 6 MCU CAPSENSE™ design guide for more details.

      3. Click Save and close CAPSENSE™ Configurator. Program the device to update the filter settings.

        4. Note : Increasing the number of sub-conversions and enabling filters will increase the scan time which in turn decreases the responsiveness of the sensor. Increase in the scan time also increases power consumption. Therefore, the number of sub-conversions and filter configurations must be optimized to achieve a balance between SNR, power, and refresh rate.

      Stage 4: Tune the threshold parameters

      Various thresholds, relative to the signal, need to be set for each sensor. Do the following in CAPSENSE™ Tuner to set up the thresholds for a widget:

      1. Switch to the Graph View tab and select Button0.

      2. Touch the sensor and monitor the touch signal in the Sensor Signal graph, as shown in Figure 21.

        Figure 21. Sensor signal when the sensor is touched


      3. When the signal is measured, set the thresholds according to the following recommendations:

        • Finger threshold = 80% of the signal

        • Noise threshold = 40% of the signal

        • Negative noise threshold = 40% of the signal

        • Hysteresis = 10% of the signal

        • Debounce = 3 (Default)

      4. Set the threshold parameters in the Widget/Sensor Parameters section of the CAPSENSE™ Tuner as shown in Figure 22.

        Figure 22. Widget threshold parameters


      5. Click Apply to Device as shown in Figure 23 to apply the settings to the device and the project.

        Figure 23. Apply settings to device

        After applying the configuration, test the performance by touching the button. If your sensor is tuned correctly, you will observe the touch status go from 0 to 1 in the Status panel of the Graph View tab as shown in Figure 24. The status of the button is also indicated by LED2 in the kit; LED2 turns ON when the finger touches the button and turns OFF when the finger is removed.

        Figure 24. Sensor status in CAPSENSE™ Tuner


      6. Click Apply to Project as shown in Figure 25. The change is updated in the design.cycapsense file. Close CAPSENSE™ Tuner and launch CAPSENSE™ Configurator. You should see all the changes made in the CAPSENSE™ Tuner are reflected in the CAPSENSE™ Configurator.

        Figure 25. Apply settings to Project

        Figure 29

        Sensor tuning parameters obtained based on the CY8CPROTO-040T, is shown in Table 4.

        Table 4. Sensor tuning parameters obtained based on sense for CY8CPROTO-040T

        Parameter Button0 LowPower0
        Signal 60 526
        Finger threshold 48 420
        Noise threshold 24 210
        Negative noise threshold 24 210
        Hysteresis 6 NA
        ON debounce 3 3
        Low baseline reset 30 30

      Process time measurement

      To set the optimum refresh rate of each power mode, measure the process time of the application.

      Perform the following steps to measure the process time of the blocks in the application code while excluding the scan time:

      1. Enable ENABLE_RUN_TIME_MEASUREMENT macro in main.c as follows:

        #define ENABLE_RUN_TIME_MEASUREMENT (1u)

        This macro enables the system tick configuration and runtime measurement functionalities.

      2. Place the start_runtime_measurement() function call before the application code and the stop_runtime_measurement() function call after it. The stop_runtime_measurement() function will return the execution time in microseconds(µs).

           #if ENABLE_RUN_TIME_MEASUREMENT
      uint32_t run_time = 0;
      start_runtime_measurement();
   #endif

   /* User Application Code Start */
   .
   .
   .
   /* User Application Code Stop */

   #if ENABLE_RUN_TIME_MEASUREMENT
      run_time = stop_runtime_measurement();
   #endif

      3. Run the application in Debug mode with breakpoints placed at the active_processing_time and alr_processing_time variables as follows:

           #if ENABLE_RUN_TIME_MEASUREMENT
      active_processing_time=stop_runtime_measurement();
   #endif
   and 
   #if ENABLE_RUN_TIME_MEASUREMENT
      alr_processing_time=stop_runtime_measurement();
   #endif

      4. Read the variables by adding them into Expressions view tab.

      5. Update related macros with earlier measured processing times in main.c as follows:

        #define ACTIVE_MODE_PROCESS_TIME     (xx)

#define ALR_MODE_PROCESS_TIME        (xx)

      Scan time Measurement

      Scan time is necessary to calculate the refresh rate of the application power modes. The total scan time of all the widgets in this code example is 12 µs.

      The scan time can be calculated as follows:

      The scan time includes the MSCLP initialization time, Cmod, and the total sub-conversions of the sensor.

      To control the Cmod initialization sequence, set the "Enable coarse initialization bypass" configurator option as listed in Table 5.

      Table. 5 Enable coarse initialization bypass

      Enable coarse initialization bypass Behaviour
      TRUE Cmod initialization happens only once before scanning the sensors of the widget
      FALSE Cmod initialization happens before scanning each sensor of the widget

      Use the following equations to measure the widgets scan time based on coarse initialization bypass options selected:

      Equation 2. Scan time calculation of a widget with coarse initialization bypass enabled

      Equation 3. Scan time calculation of a widget with coarse initialization bypass disabled

      where,

      $n$ - Total number of sensors in the widget

      $N_{init}$ - Number of init sub-conversions

      $N_{sub}$ - Number of sub-conversions

      $SnsClkDiv$ - Sense clock divider

      $F_{mod}$ - Modulator clock frequency

      $k$ - Measured Initialization time (MSCLP+Cmod).

      The value of $k$ measured for this application is ~9.865 µs. It remains constant for all widgets.

      $k$ can be measured using oscilloscope, as shown in Figure 26.

      Figure 26. '$k$' value measurement


      Update the following macros in main.c using the calculated scan time. For this application, the value remains the same for both macros.

      #define ACTIVE_MODE_FRAME_SCAN_TIME     (xx)

#define ALR_MODE_FRAME_SCAN_TIME        (xx)

      Note : If the application has more than one widget, add the scan time of individual widgets calculated.


      Debugging

      You can debug this project 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.

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

      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.

      Design and implementation

      The project contains a button 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 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 successful tuning of the button is indicated by an LED in the pioneer kit; the LED2 is turned ON when the finger touches the button and turned OFF when the finger is removed from the button.

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

      1. Open Device configurator from the Quick Panel.

      2. Go to the System tab. Select the Power resource, and set the VDDA value under Operating Conditions as shown in Figure 27.

        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 28.

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

      Resources and settings

      The EZI2C configurations used for tuner communications are shown in Figure 29.

      Figure 29. EZI2C settings


      Table 6. Application resources

      Resource Alias/object Purpose
      SCB (EZI2C) (PDL) CYBSP_EZI2C EZI2C slave driver to communicate with CAPSENSE™ Tuner
      CAPSENSE™ CYBSP_MSC CAPSENSE™ driver to interact with the MSCLP hardware and interface the CAPSENSE™ sensors
      Digital pin CYBSP_USER_LED2, CYBSP_USER_BTN To show the button operation

      Firmware flow

      Figure 30. 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
      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 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.

      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: CE238820 - PSoC™ 4: MSCLP low-power mutual-capacitance button

      Version Description of change
      1.0.0 New code example
      2.0.0 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, 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.