This example shows how to use a smart I/O peripheral in PSoC™ 4 device to implement a clock buffer that can operate in chip low-power modes. It can also be used to drive a heavier load than one GPIO is rated for by replicating the signal and driving two pins.
Provide feedback on this code example.
- 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™ 4000S, PSoC™ 4100S Plus, PSoC™ 4100S Max, and PSoC™ 4500S
- 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™ 4100S Max Pioneer Kit (
CY8CKIT-041S-MAX) – Default value ofTARGET - PSoC™ 4100S Plus Prototyping Kit (
CY8CKIT-149) - PSoC™ 4000S CAPSENSE™ Prototyping Kit (
CY8CKIT-145-40XX) - PSoC™ 4500S Pioneer Kit (
CY8CKIT-045S)
- Connect IN_PIN to a square wave source (e.g. from a signal generator) that is less than 1 MHz and to an oscilloscope.
- Connect OUT_PIN_0 and OUT_PIN_1 to an oscilloscope.
- Connect TRIG_PIN to GND (Alternatively use an external active high switch).
For all the four kits (CY8CKIT-41S-MAX,CY8CKIT-149,CY8CKIT-145-40XX, and CY8CKIT-045S) smart I/O uses port 2.
Table 1. Smart I/O pin connections
| Pin Name | Resource |
|---|---|
| IN_PIN | P2[1] |
| TRIG_PIN | P2[2] |
| OUT_PIN_0 | P2[3] |
| OUT_PIN_1 | P2[5] |
- For CY8CKIT-045S OUT_PIN_1 is configured to P2[6].
Note: Some of the PSoC™ 4 kits ship with KitProg2 installed. The ModusToolbox™ software 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 If you do not upgrade, you will see an error like "unable to find CMSIS-DAP device" or "KitProg firmware is out of date".
The smart I/O peripheral is a port-wide resource; you must define its port before it can be used.
Default port is Port 2 for CY8CKIT-041S-MAX, CY8CKIT-149, CY8CKIT-145-40XX, and CY8CKIT-045S.
Table 2. STATUS_PIN resource connection
| Pin Name | CY8CKIT-41S-MAX | CY8CKIT-149 | CY8CKIT-145-40XX | CY8CKIT-045S |
|---|---|---|---|---|
| STATUS_PIN | P7[3] | P1[4] | P3[6] | P1[6] |
Note: STATUS_PIN is connected to LED.
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).
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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 "mtb-example-psoc4-clock-buffer-with-smart-io" application with the desired name "ClockBufferSmartIO" configured for the CY8CKIT-041S-MAX BSP into the specified working directory, C:/mtb_projects:
project-creator-cli --board-id CY8CKIT-041S-MAX --app-id mtb-example-psoc4-clock-buffer-with-smart-io --user-app-name ClockBufferSmartIO --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).
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Connect the board to your PC using the provided USB cable through the KitProg3 USB connector.
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Program the board using one of the following:
Using Eclipse IDE
-
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).
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 -
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After programming, observe that the signal going into IN_PIN is replicated on OUT_PIN_0 and OUT_PIN_1. These are operational during deep-sleep mode; the two signals can be externally ganged to drive a higher load.
-
Connect TRIG_PIN to VDD and then connect it back to GND. Alternatively push the external active high switch connected to TRIG_PIN. Observe that the LED connected to STATUS_PIN lights up for approximately 1 second. Observe that the OUT_PIN_0 and OUT_PIN_1 continue to operate regardless of chip power mode.
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.
In other IDEs
Follow the instructions in your preferred IDE.
Note: As the program enters the deepsleep mode debugging will not work as desired. As debug connection will be interrupted.
The design consists of a smart I/O peripheral with only the pins on the port as its inputs and outputs. It does not use any peripherals or internal chip signals. The peripheral performs a signal replication function by taking in an external signal (such as an external clock) and driving it out to two pins. This effectively implements a signal buffer functionality. The two pins can then be ganged externally to the chip to drive a load that is higher than rated for a single GPIO pin.
The smart I/O peripheral is operational during the device’s deep-sleep mode. This design shows how multiple signals can be used in the smart I/O peripheral to trigger an interrupt that is the result of a logical operation on those signals.
For the clock buffer, an external signal is input through I/O 1, which in turn is connected to IN_PIN. This signal is repeated and output to I/O 3 and I/O 5. These are connected to OUT_PIN_0 and OUT_PIN_1 respectively.
For interrupt generation, the peripheral accepts a digital input signal through I/O 2, which is connected to TRIG_PIN. This signal is logically ANDed with I/O 1 by using LUT0. The result is output to I/O 0, triggers the GPIO interrupt on INTR_PIN. The INTR_PIN is configured to generate a GPIO interrupt on a rising edge signal. A digital output STATUS_PIN is used to signal the LED via firmware for device wakeup indication.
The firmware is implemented in main.c and performs the following functions:
- Initialize and enable GPIO interrupt
- Starts the smart I/O peripheral
- Device enters deep sleep mode
- When the interrupt is triggered, the device wakes up and drives the STATUS_PIN high for 1 second
- STATUS_PIN is driven LOW; device re-enters deep sleep
Note: This code example is designed for the specified ports on the stated devices. The design is portable to other PSoC™ 4 devices with smart I/O, but it may require LUT reconfiguration due to the close relationship between the device port and the peripheral.
Table 3. Application resources
| Resource | Alias/object | Purpose |
|---|---|---|
| SmartIO | SMART_IO | Perform simple logic operations on peripheral and GPIO signals at the GPIO port |
| Pins | OUT_PIN_0, OUT_PIN_1, INTR_PIN, IN_PIN, TRIG_PIN, STATUS_PIN | GPIO Signals |
| Interrupt | switch_isr | Switch interrupt |
The smart I/O peripheral is configured in "Asynchronous mode".
Figure 1: Smart I/O routing configuration
Figure 2 shows the LUT configurations. Only combinatorial elements are used; the block is operational in chip deep sleep mode. LUT0 accepts I/O 1 and I/O 2 as inputs. The LUT configuration performs a logical AND of these signals and outputs the result to I/O 0. This is used to trigger the wakeup event on the GPIO. LUT1 is configured to repeat the I/O 1 signal. Its output is fed to LUT3 and LUT5. Note that that there are two reasons why two LUTs are used per path (LUT1->LUT3 and LUT1->LUT5):
-
LUT4 to LUT7 cannot accept I/O [3:0] or chip [3:0] as inputs. An intermediary LUT must be used.
-
LUT3 can directly accept I/O 1 as input but LUT5 cannot. If the design requires that the signals appearing in I/O 3 and I/O 5 must be in sync, an intermediary LUT should be used to minimize path delay difference.
LUT3 and LUT5 are configured to repeat the LUT1 output signal. These are then output through I/O 3 and I/O 5 respectively.
Note: For CY8CKIT-045S, pin P2[6] is used instead of P2[5], hence LUT6 is configured instead of LUT5.
Figure 2. Smart I/O LUT configuration
| Resources | Links |
|---|---|
| Application notes | AN79953 – Getting started with PSoC™ 4 |
| Code examples | Using ModusToolbox™ software on GitHub Using PSoC™ Creator |
| Device documentation | Download datasheets, TRMs, and other documents from the PSoC™ 4 product page |
| 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™ 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.
Document title: CE236713 – PSoC™ 4: Clock buffer with smart I/O
| 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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