PSoC™ 4: Comparing two external voltages using LPComp

The code example demonstrates how to compare two external signals connected at the LPComp inputs and indicate the result using LEDs.

View this README on GitHub.

Provide feedback on this code example.

Requirements

• ModusToolbox™ v3.1 or later (tested with v3.1)
• Board support package (BSP) minimum required version: 3.1.0
• Programming language: C
• Associated parts: PSoC™ 4100S Plus, PSoC™ 4000S, and PSoC™ 4500S

Supported toolchains (make variable 'TOOLCHAIN')

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

Supported kits (make variable 'TARGET')

• PSoC™ 4100S Plus Prototyping Kit (CY8CKIT-149) – Default value of TARGET
• PSoC™ 4000S CAPSENSE™ Prototyping Kit (CY8CKIT-145-40XX)
• PSoC™ 4500S Pioneer Kit (CY8CKIT-045S)

Hardware setup

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

2. Connect a function generator output to a Vplus pin.

Note: Make common ground between the board and the function generator.

3. Supply a reference voltage (0.8 V) from an external source to the Vminus pin.

4. When default device configurator configurations are enabled:

• Connect a jumper wire from P2[7] to P2[2] (LED) for CY8CKIT-149 and CY8CKIT-145-40XX.
• Connect a jumper wire from P3[7] to P0[0] for CY8CKIT-045S.

Pins	CY8CKIT-149	CY8CKIT-145-40XX	CY8CKIT-045S
Vplus	P0[0]	P0[0]	P0[2]
Vminus	P0[1]	P0[1]	P0[3]

Note: Some of the PSoC™ 4 kits ship with KitProg2 installed. The ModusToolbox™ requires KitProg3. Before using this code example, make sure that the board is upgraded to KitProg3. The tool and instructions are available in the Firmware Loader GitHub repository. If you do not upgrade, you will see an error like "unable to find CMSIS-DAP device" or "KitProg firmware is out of date".

Software setup

See the ModusToolbox™ tools package installation guide for information about installing and configuring the tools package. This example requires no additional software or tools.

Using the code example

Create the project

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

Use Project Creator GUI

1. Open the Project Creator GUI tool.

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

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

   Note: To use this code example for a kit not listed here, you may need to update the source files. If the kit does not have the required resources, the application may not work.

3. On the Select Application page:

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

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

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

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

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

   d. Click Create to complete the application creation process.

Use Project Creator CLI

The 'project-creator-cli' tool can be used to create applications from a CLI terminal or from within batch files or shell scripts. This tool is available in the {ModusToolbox™ install directory}/tools_{version}/project-creator/ directory.

Use a CLI terminal to invoke the 'project-creator-cli' tool. On Windows, use the command-line 'modus-shell' program provided in the ModusToolbox™ installation instead of a standard Windows command-line application. This shell provides access to all ModusToolbox™ tools. You can access it by typing "modus-shell" in the search box in the Windows menu. In Linux and macOS, you can use any terminal application.

The following example clones the "mtb-example-psoc4-comparing-two-external-voltages-using-lpcomp" application with the desired name "ComparingTwoExternalVoltagesUsingLpcomp" configured for the CY8CKIT-149 BSP into the specified working directory, C:/mtb_projects:

project-creator-cli --board-id CY8CKIT-149 --app-id mtb-example-psoc4-comparing-two-external-voltages-using-lpcomp --user-app-name ComparingTwoExternalVoltagesUsingLpcomp --target-dir "C:/mtb_projects"

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

Argument	Description	Required/optional
--board-id	Defined in the field of the BSP manifest	Required
--app-id	Defined in the field of the CE manifest	Required
--target-dir	Specify the directory in which the application is to be created if you prefer not to use the default current working directory	Optional
--user-app-name	Specify the name of the application if you prefer to have a name other than the example's default name	Optional

Note: The project-creator-cli tool uses the git clone and make getlibs commands to fetch the repository and import the required libraries. For details, see the "Project creator tools" section of the ModusToolbox™ tools package user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mtb_user_guide.pdf).

Open the project

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

Eclipse IDE

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

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

Visual Studio (VS) Code

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

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

Keil µVision

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

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

IAR Embedded Workbench

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

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

Command line

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

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

Operation

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

2. To generate a sine wave, configure the function generator output to the Vplus pin. The sine wave must be equal to or higher than 0 V (in this code example, it uses 0 V to 1.6 V and 1 Hz).

3. The reference voltage must be higher than the minimum voltage of the sine wave and lower than the maximum voltage of the sine wave (in this code example, it uses 0.8 V).

4. In main.c, to demonstrate how PDL drivers are used to manually configure the peripherals, set the PDL_CONFIGURATION #define to 1, otherwise, set it to 0.

5. Enable the output of the function generator.

6. 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
   

7. Confirm that LED toggles follow the sine wave frequency.

Note: The following table shows the LEDs and PDL configurations for the supported PSoC™ 4 kits.

Table 1. PDL configurations for PSoC™ 4 kits

BSP	PDL_CONFIGURATION = 0	PDL_CONFIGURATION = 1
CY8CKIT-149	LED 7 (P2[2])	LED 6 (P2[0])
CY8CKIT-145-40XX	LED 4 (P2[2])	LED 2 (P2[0])
CY8CKIT-045S	User LED (P0[0])	User LED (P1[6])

Debugging

You can debug the example to step through the code.

In Eclipse IDE

Use the <Application Name> Debug (KitProg3_MiniProg4) configuration in the Quick Panel. For details, see the "Program and debug" section in the Eclipse IDE for ModusToolbox™ user guide.

Note: (Only while debugging) On the CM4 CPU, some code in main() may execute before the debugger halts at the beginning of main(). This means that some code executes twice – once before the debugger stops execution, and again after the debugger resets the program counter to the beginning of main(). See KBA231071 to learn about this and for the workaround.

In other IDEs

Follow the instructions in your preferred IDE.

Design and implementation

This design consists of one LPComp, one GPIO for the status LED, and two GPIOs for analog inputs. The positive terminal (Vplus) connects to the output of a function generator to input the sine wave (in this example, the sine wave has a 0.8-V offset, 1.6-Vpp, and 1-Hz frequency). The negative terminal (Vminus) connects to the reference voltage (in this example, the voltage is 0.8 V). The comparison result from the comparator out terminal is routed directly to the LED pin. Because of this routing, the LED indicates the comparison result without any additional firmware code.

The status LED shows the voltage comparison result. If the positive terminal input is higher than the negative terminal input, the LED is OFF; it is ON otherwise.

Resources and settings

Table 2. Application resources

Resource	Alias/object	Purpose
Low Power Comparator (PDL)	LPComp	Compare two low-power voltages.
Analog pin	Vplus	Read/Write analog values.
Analog pin	Vminus	Read/Write analog values.
LED (BSP)	CYBSP_USER_LED	User LED to show output.

Related resources

Resources	Links
Application notes	AN79953 – Getting started with PSoC™ 4
Code examples	Using ModusToolbox™ on GitHub
Device documentation	PSoC™ 4 datasheets PSoC™ 4 technical reference manuals
Development kits	Select your kits from the Evaluation board finder page
Libraries on GitHub	mtb-pdl-cat2 – PSoC™ 4 Peripheral Driver Library (PDL) mtb-hal-cat2 – Hardware Abstraction Layer (HAL) library
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. PSoC™ Creator – IDE for PSoC™ and FM0+ MCU development

Other resources

Infineon provides a wealth of data at www.infineon.com to help you select the right device, and quickly and effectively integrate it into your design.

Document history

Document title: CE236921 - PSoC™ 4: Comparing two external voltages using LPComp

Version	Description of change
1.0.0	New code example
1.1.0	Added support for CY8CKIT-045S and updated to support ModusToolbox™ v3.1

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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.

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