This code example demonstrates the generation of asymmetric PWM signals using two compare/capture registers available in the TCPWM block of the PSoC™ 6 MCU devices. Compared to the asymmetric PWM realized with only one compare function (where the CPU is used to update the compare value twice every PWM cycle), this solution uses two independent buffered compare values and causes less load on the CPU (where the CPU is used to update the compare value once every PWM cycle). This document discusses these advantages and applications in field-oriented control (FOC).
Provide feedback on this code example.
- ModusToolbox™ software v3.0
- Board support package (BSP) minimum required version: 4.0.0
- Programming language: C
- Associated parts: All CY8C62x4 parts
- GNU Arm® embedded compiler v10.3.1 (
GCC_ARM) - Default value ofTOOLCHAIN - Arm® compiler v6.16 (
ARM) - IAR C/C++ compiler v9.30.1 (
IAR)
- PSoC™ 62S4 pioneer kit (
CY8CKIT-062S4) - Default value ofTARGET
This example uses the board's default configuration. See the kit user guide to ensure that the board is configured correctly.
Install a terminal emulator if you don't have one. Instructions in this document use Tera Term.
Create the project and open it using one of the following:
In Eclipse IDE for ModusToolbox™ software
-
Click the New Application link in the Quick Panel (or, use File > New > ModusToolbox Application). This launches the Project Creator tool.
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Pick a kit supported by the code example from the list shown in the Project Creator - Choose Board Support Package (BSP) dialog.
When you select a supported kit, the example is reconfigured automatically to work with the kit. To work with a different supported kit later, use the Library Manager to choose the BSP for the supported kit. You can use the Library Manager to select or update the BSP and firmware libraries used in this application. To access the Library Manager, click the link from the Quick Panel.
You can also just start the application creation process again and select a different kit.
If you want to use the application 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.
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In the Project Creator - Select Application dialog, choose the example by enabling the checkbox.
-
(Optional) Change the suggested New Application Name.
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The Application(s) Root Path defaults to the Eclipse workspace which is usually the desired location for the application. If you want to store the application in a different location, you can change the Application(s) Root Path value. Applications that share libraries should be in the same root path.
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Click Create to complete the application creation process.
For more details, see the Eclipse IDE for ModusToolbox™ software user guide (locally available at {ModusToolbox™ software install directory}/ide_{version}/docs/mt_ide_user_guide.pdf).
In command-line interface (CLI)
ModusToolbox™ software provides the Project Creator as both a GUI tool and the command line tool, "project-creator-cli". The 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™ software 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™ software installation instead of a standard Windows command-line application. This shell provides access to all ModusToolbox™ software 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.
This tool has the following arguments:
| Argument | Description | Required/optional |
|---|---|---|
--board-id |
Defined in the <id> field of the BSP manifest |
Required |
--app-id |
Defined in the <id> 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 |
The following example will clone the "mtb-example-psoc6-pwm-dual-compare-capture" application with the desired name "Psoc6PwmDualCC" configured for the CY8CKIT-062S4 BSP into the specified working directory, C:/mtb_projects:
project-creator-cli --board-id CY8CKIT-062S4 --app-id mtb-example-psoc6-pwm-dual-compare-capture --user-app-name Psoc6PwmDualCC --target-dir "C:/mtb_projects"
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™ software user guide (locally available at {ModusToolbox™ software install directory}/docs_{version}/mtb_user_guide.pdf).
In third-party IDEs
Use one of the following options:
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Use the standalone Project Creator tool:
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Launch Project Creator from the Windows Start menu or from {ModusToolbox™ software install directory}/tools_{version}/project-creator/project-creator.exe.
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In the initial Choose Board Support Package screen, select the BSP, and click Next.
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In the Select Application screen, select the appropriate IDE from the Target IDE drop-down menu.
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Click Create and follow the instructions printed in the bottom pane to import or open the exported project in the respective IDE.
-
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Use command-line interface (CLI):
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Follow the instructions from the In command-line interface (CLI) section to create the application, and then import the libraries using the
make getlibscommand. -
Export the application to a supported IDE using the
make <ide>command. -
Follow the instructions displayed in the terminal to create or import the application as an IDE project.
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For a list of supported IDEs and more details, see the "Exporting to IDEs" section of the ModusToolbox™ software user guide (locally available at {ModusToolbox™ software install directory}/docs_{version}/mtb_user_guide.pdf).
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Connect the board to your PC using the provided USB cable through the KitProg3 USB connector.
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Open a terminal program and select the KitProg3 COM port. Set the serial port parameters to 8N1 and 115200 baud.
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Program the board using one of the following:
Using Eclipse IDE for ModusToolbox™ software
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Select the application project in the Project Explorer.
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In the Quick Panel, scroll down, and click <Application Name> Program (KitProg3_MiniProg4).
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 and target are specified in the application's Makefile but you can override those values manually:make program TARGET=<BSP> TOOLCHAIN=<toolchain>Example:
make program TARGET=CY8CKIT-062S4 TOOLCHAIN=GCC_ARM -
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After programming, the application starts automatically. Confirm that the title of this document (PSoC™ 6 MCU: TCPWM in PWM Mode with Dual Compare/Capture) and instructions are printed on the terminal.
Figure 1. CE title and instructions
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Tap out the following pins to an oscilloscope:
- P5_0 - PWM output (periodic square wave)
- P6_4 - Terminal count (marks the end of the period)
- P6_5 - Overflow (marks the center of the period)
-
Verify on the oscilloscope that a center-aligned square wave with a 50% duty cycle is generated on P5_0. Use the signals from P6_4 and P6_5 to verify the alignment.
Figure 2. Initial waveform
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Follow the instructions printed on the terminal to modify the waveform. Verify the output on the oscilloscope simultaneously.
Figure 3. Increase the duty cycle
Figure 4. Decrease the duty cycle
Figure 5. Shift the waveform left
Figure 6. Shift the waveform right
You can debug the example 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™ software 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.
This code example demonstrates generating asymmetric PWM signals using dual compare/capture. The configuration required for the TCPWM block is done in a custom design.modus file.
An asymmetric PWM signal is a center-aligned PWM, which is shifted either to the left or right. In this mode, the counter counts up until its counter value reaches the period and then counts down until it becomes zero (repeats itself). The value in the CC0 register is used as a match when counting up, and the value in the CC1 register is used as a match when counting down. When the counter value matches the CC0 register value, the PWM signal goes HIGH and when the counter value matches the CC1 register value, the PWM signal goes LOW. Thus, by having different CC0 and CC1 register values, you can generate asymmetric PWM signals of any width and phase.
Figure 7. TCPWM configurations in custom design file
The Debug UART is used to accept commands from the terminal. A callback is generated upon every command received. The CC0_Buff and CC1_Buff register values are modified according to the command. A swap is then triggered to exchange CC and CC_Buff values.
The advantage of using dual compare/capture registers to generate asymmetric PWM signals is the reduction in CPU bandwidth usage. With only one CC register, the application must write new values to CC_Buff registers every half a cycle. With two CC registers, the application need to write new values to CC_Buff registers only once every cycle, thereby reducing the CPU bandwidth usage by half.
Asymmetric PWMs are widely used in field-oriented control to drive gates of MOSFET bridges. The duty cycle of the PWM signals is modulated in the form of a sine wave to generate the required vectors. Asymmetric PWMs are used to introduce temporary phase shifts to measure single-shunt current. The single-shunt design reduces the cost and complexity of the motor control application significantly.
Table 1. Application resources
| Resource | Alias/object | Purpose |
|---|---|---|
| TCPWM (PDL) | TCPWM0_GRP1_CNT0 | PWM block to generate asymmetric waveforms |
| UART (HAL) | cy_retarget_io_uart_obj | UART HAL object used by Retarget-IO for debug UART port |
| GPIO (PDL) | pwm_output | Brings out the PWM output signal |
| GPIO (PDL) | terminal_count | Brings out the terminal count signal |
| GPIO (PDL) | overflow | Brings out the overflow signal |
| Resources | Links |
|---|---|
| Application notes | AN228571 – Getting started with PSoC™ 6 MCU on ModusToolbox™ software AN221774 – Getting started with PSoC™ 6 MCU on PSoC™ Creator AN210781 – Getting started with PSoC™ 6 MCU with Bluetooth® Low Energy connectivity on PSoC™ Creator AN215656 – PSoC™ 6 MCU: Dual-CPU system design |
| Code examples | Using ModusToolbox™ software on GitHub Using PSoC™ Creator |
| Device documentation | PSoC™ 6 MCU datasheets PSoC™ 6 technical reference manuals |
| Development kits | Select your kits from the Evaluation board finder page |
| Libraries on GitHub | mtb-pdl-cat1 – PSoC™ 6 peripheral driver library (PDL) mtb-hal-cat1 – Hardware abstraction layer (HAL) library retarget-io – Utility library to retarget STDIO messages to a UART port |
| Middleware on GitHub | capsense – CAPSENSE™ library and documents psoc6-middleware – Links to all PSoC™ 6 MCU middleware |
| Tools | Eclipse IDE for ModusToolbox™ software – ModusToolbox™ software is a collection of easy-to-use software and tools enabling rapid development with Infineon MCUs, covering applications from embedded sense and control to wireless and cloud-connected systems using AIROC™ Wi-Fi and Bluetooth® connectivity devices. PSoC™ Creator – IDE for PSoC™ and FM0+ MCU 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.
For PSoC™ 6 MCU devices, see How to design with PSoC™ 6 MCU - KBA223067 in the Infineon community.
Document title: CE230816 - PSoC™ 6 MCU: TCPWM in PWM mode with dual compare/capture
| Version | Description of change |
|---|---|
| 1.0.0 | New code example |
| 2.0.0 | Update to support v2.X CY8CKIT-062S4 BSP |
| 3.0.0 | Major update to support ModusToolbox™ v3.0 and BSPs v4.x. This version is not backward compatible with previous versions of ModusToolbox™ software |
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