This code example implements a low-power, liquid-tolerant, and robust capacitive-sensing solution with the PSoC™ 4000T device using the CY8CKIT-040T CAPSENSE™ Evaluation Kit.
This code example demonstrates the advanced features of the multi-sense converter low-power (MSCLP), 5th-generation CAPSENSE™ block in PSoC™ 4000T. This kit has onboard capacitive sensors (a self-capacitance touch button, a proximity sensor, and a touchpad) that operate in an ultra-low-power mode and only respond to a valid finger touch. The sensors are deactivated when any liquid is present on the sensors. The kit has onboard LEDs to indicate different touch operations.
Use only the CY8CKIT-040T CAPSENSE™ kit for testing this code example.
Provide feedback on this code example.
- ModusToolbox™ v3.2 or later
Note: This code example version requires ModusToolbox™ version 3.2 and is not backward compatible with v3.1 or older versions.
- Board support package (BSP) minimum required version: 3.1.0
- Programming language: C
- Associated parts: PSoC™ 4000T
- GNU Arm® Embedded Compiler v11.3.1 (
GCC_ARM) – Default value ofTOOLCHAIN - Arm® Compiler v6.16 (
ARM) - IAR C/C++ Compiler v9.30.1 (
IAR)
- PSoC™ 4000T CAPSENSE™ Evaluation Kit (
CY8CKIT-040T) – Default value ofTARGET
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.
See the ModusToolbox™ tools package installation guide for information about installing and configuring the tools package. This example requires no additional software or tools.
The ModusToolbox™ tools package provides the Project Creator as both a GUI tool and a command line tool.
Use Project Creator GUI
-
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).
-
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.
-
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 "PSoC™ 4: MSCLP robust low-power liquid-tolerant CAPSENSE™" application with the desired name "MSCLPliquidTolCAPSENSE" 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-capsense-demo --user-app-name MSCLPliquidTolCAPSENSE --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 cloneandmake getlibscommands 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).
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).
-
Connect the USB cable between the CY8CKIT-040T kit and the PC as shown in Figure 1.
Figure 1. Connecting the CY8CKIT-040T kit with the PC
-
Program the board using one of the following:
Using Eclipse IDE
-
Select the application project in the Project Explorer.
-
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 programcommand 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 -
-
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 the debug mode will solve this error.
"Error: Error connecting Dp: Cannot read IDR" -
Touch any of the sensors with your finger. LEDs turn ON indicating the activation of different CAPSENSE™ sensors in the following pattern:
- LED1 turn ON in blue when the button is touched
- LED1 and LED3 turn ON in green when the touchpad is touched
- LED1 brightness increases when the finger is swiped from left to right
- LED3 brightness increases when the finger is swiped from bottom to top
-
For the liquid tolerance use cases mentioned, observe that all the LEDs are OFF, indicating that no false trigger occurs due to the presence of water. See the kit user guide to learn more about the test procedure.
-
Use a water dropper (shipped with the kit package) to place water droplets on top of the sensors.
-
Spray water over the sensors as shown in Figure 2.
-
Dip the kit in water, up to the immersible line as shown in Figure 3.
-
You can splash or pour water over the kit below the immersible line as shown in Figure 4 and Figure 5.
Note: Ensure to not have water above the immersible line while testing out liquid tolerance.
-
-
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.
-
Ensure that the status LED is ON and not blinking. This indicates that the onboard KitProg3 is in CMSIS-DAP bulk mode. See Firmware-loader to learn how to update the firmware and switch modes in KitProg3.
-
In the tuner application, click on the Tuner Communication Setup icon or select Tools > Tuner Communication Setup.
In the window that appears, select the I2C checkbox under KitProg3 and configure it as shown in Figure 7.
- I2C address: 8
- Sub-address: 2-Bytes
- Speed (kHz): 400
These are the same values set in the EZI2C resource.
-
Click Connect or select Communication > Connect to establish a connection.
-
Click Start or select Communication > Start to start data streaming from the device.
The Widget/Sensor Parameters tab is updated with the parameters configured in the CAPSENSE™ Configurator window. The tuner displays the data from the sensor in the Widget View, Graph View, and Touchpad View tabs.
-
Set the Read mode to Synchronized mode. Navigate to the Widget View tab and observe that the different sensor widgets is highlighted in blue color when you touch it.
-
Go to the Graph View tab to view the raw count, baseline, difference count, status and touchpad position for each sensor. To view the sensor data for a button, select BUTTON_Sns0 under BUTTON (see Figure 9). To view the touchpad sensor data, select TOUCHPAD_Col0 under TOUCHPAD (see Figure 10).
-
Go to the Touchpad View tab to view the heatmap, that visualizes the finger movement.
- Go to 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 10.
To observe the CAPSENSE™ data at a higher refresh rate and for specific sensors, see Using Bridge Control Panel to view CAPSENSE™ data – KBA237056.
CY8CKIT-040T kit 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's functionalities are optimally tuned for 1.8 V. However, you can observe its basic functionalities working across other voltages.
It is recommended to tune the application to the preferred voltages for better performance.
-
Disable the serial LED and tuner macros to measure the current used for CAPSENSE™ sensing in each power mode in main.c and self-test library from the CAPSENSE™ configurator as follows:
#define ENABLE_SERIAL_LED (0u) #define ENABLE_TUNER (0u) -
Disable the self-test library from the CAPSENSE™ Configurator as shown in Figure 12.
-
Disable the debug mode (if enabled). By default, it is disabled. To enable, see the setup the VDDA supply voltage and debug mode in Device Configurator section. Enabling the debug mode keeps the SWD pins active in all device power modes including the Deep Sleep mode. This leads to an increase in power consumption.
-
Connect the kit to a power analyzer such as KEYSIGHT – N6705C using a current measure header to evaluate the low-power feature of the device as shown in Figure 13.
-
Control the power analyzer device through the laptop using the software tool Keysight BenchVue Advanced Power Control and Analysis.
-
Select the Current measurement option from the Instrument Control setup and turn ON the output channel as shown in Figure 14.
-
Capture the data using the Data Logger option from the tool. The average current consumption is measured using the cursors on each power mode as shown in Figure 15.
-
If there is touch detection on one of the sensors, the device is in Active state. Measure the device current during the active state of operation. If the refresh rate is set to 128 Hz, the approximate device current would be 309 µA when the touchpad is touched (see Figure 16).
-
If there is no touch detection on any of the sensors for some time, the CAPSENSE™ block moves to a state called Active low-refresh rate (ALR). If the refresh rate of this state is set to 32 Hz, the approximate device current would be 81 µA.
-
Further inactivity in any of the sensors, moves the CAPSENSE™ block to a low-power state, that is the Wake-on-Touch (WoT) state. The device current in this state is approximately 5 µA, if the refresh rate is set to 16 Hz.
The following table shows the current values measured for VDD = 1.8 V:
Table 1. Device current at different application states
| Application state | Refresh rate (Hz) | Current (µA) |
|---|---|---|
| Wake-on-touch | 16 | 5 |
| Active low-refresh rate | 32 | 81 |
| Active | 128 | 309 |
-
Create a custom BSP for your board having any device, by following the steps given in the ModusToolbox™ BSP Assistant user guide. In this code example, it is created for the "CY8C4046LQI-T452" device.
-
Open the design.modus file from {Application root directory}/bsps/TARGET_APP_<BSP-NAME>/config/ folder obtained in the previous step and enable CAPSENSE™ to get the design.cycapsense file. The CAPSENSE™ configuration can then be started from scratch as follows.
This code example has the optimum tuning parameters for all the sensors. See the following code examples that describe the tuning procedures of different sensors:
-
CE235178 for self-capacitance button tuning procedure
-
CE235338 for self-capacitance touchpad tuning procedure
-
CE235111 for tuning the low-power widget of the PSoC™ 4000T device
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 the VDDA and debug mode section. To achieve low power consumption, it is recommended to disable it.
The project uses CAPSENSE™ middleware; see the 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 design has a ratiometric implementation of the following sensors, as shown in Figure 17.
-
One Wake-on-Touch widget (1 element), also called "low-power widget"
-
One self-capacitance button widget (1 element)
-
One touchpad widget with 9 elements (4 rows and 5 columns)
-
Proximity sensor of the board configured as a self-capacitance guard sensor (1 element)
-
Proximity sensor of the board configured as a mutual-capacitance guard sensor (1 element)
The design also has an EZI2C peripheral and an SPI master peripheral.
The EZI2C slave peripheral is used to monitor the information of a sensor's raw and processed data on a PC using the CAPSENSE™ Tuner available in the Eclipse IDE for ModusToolbox™ via I2C communication.
The master out slave in (MOSI) pin of the SPI slave peripheral is used to transfer data to the three serially connected LEDs for controlling color, brightness, and ON/OFF operation.
This project uses the self-capacitance and mutual-capacitance guard sensors to detect the presence of liquid on the board. The following liquid tolerance use cases can be detected using this project:
- Dipping the kit in water
- Spraying water over the sensors
- Presence of water droplets on top of the sensors
- Pouring water over the kit
- Splashing water over the kit
The firmware is designed to support the following CAPSENSE™ states by using the PSoC™ 4000T device:
- Active state
- Active low-refresh rate state
- Wake-on-Touch state
- Liquid active state
The firmware state machine and its operation in four different states in the device are explained in the following steps:
-
Initializes and starts all hardware components after reset.
-
The device starts CAPSENSE™ operation in the Active state. The following steps will occur in this state:
-
The device scans all CAPSENSE™ sensors present on the board.
-
During the ongoing scan operation, the CPU moves to the Deep Sleep state.
-
The interrupt generated on scan completion wakes the CPU, which processes the sensor data and transfers the data to CAPSENSE™ Tuner through EZI2C.
-
Turns on the serial LED with specific colors and patterns to indicate the specific touch operation.
In Active state, a scan of the selected sensors is carried out with the highest refresh rate of 128 Hz.
-
-
Enters the Active low-refresh rate state when there is no touch detected for a timeout period. During this state, a scan of selected sensors is carried out with a lower refresh rate of 32 Hz. Power consumption in the Active low-refresh rate state is lower, compared to the Active state. The state machine returns to the Active state if there is any touch detected on any sensor.
-
Enters the Wake-on-Touch state when there is no touch detected in the Active low-refresh rate state for a timeout period. In this state, the CPU completely moves to Deep Sleep, and does not get involved in CAPSENSE™ operation. This is the lowest power state of the device. In the Wake-on-Touch state, the CAPSENSE™ hardware executes the scanning of the selected sensors called "low-power widgets" and processes the scan data for these widgets. If any touch is detected, the CAPSENSE™ block wakes up the CPU and the device moves back to the Active state.
-
Enters the Liquid active state when one of the guard sensors is activated. This state restricts normal scan operation and avoids any false touch by deactivating the scan operation of active sensors. When the liquid is removed from the senor, CAPSENSE™ moves to the Active state.
There are three onboard LEDs connected to the SPI MOSI pin of the device. 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 colors.
-
Open Device Configurator from the Quick Panel.
-
Go to the System tab. Select the Power resource, and set the VDDA value under Operating Conditions as shown in Figure 19.
-
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 20.
The following ModusToolbox™ resources are used in this example:
Table 2. Application resources
| Resource | Alias/object | Purpose |
|---|---|---|
| SCB (I2C) (PDL) | CYBSP_EZI2C | EZI2C slave driver to communicate with CAPSENSE™ Tuner |
| CAPSENSE™ | CYBSP_MSCLP0 | CAPSENSE™ driver to interact with the MSCLP hardware and interface the CAPSENSE™ sensors |
| Digital pin | CYBSP_MASTER_SPI | SPI Master driver to serial LEDs which visualize touchpad and button response |
| 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 page |
| 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. |
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 title: CE234752 – PSoC™ 4: MSCLP robust low-power liquid-tolerant CAPSENSE™
| Version | Description of change |
|---|---|
| 1.0.0 | New code example |
| 1.0.1 | Minor readme update |
| 1.1.0 | Updated code example for improving liquid tolerance |
| 2.0.0 | Major update to support ModusToolbox™ v3.0 This version is not backward compatible with previous versions of ModusToolbox™ |
| 3.0.0 | Major update to support ModusToolbox™ v3.1 and the BSP changes This version is not backward compatible with previous versions of ModusToolbox™ |
| 3.0.1 | Minor configuration and readme update |
| 4.0.0 | 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 referenced product or service names and trademarks 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.