This code example uses a SPI resource and smart I/O in PSoC™ 6 MCU to implement the Inter-IC Sound (I2S) master interface (Tx only).
Provide feedback on this code example.
- ModusToolbox™ software v3.0 or later (tested with v3.0)
- Board support package (BSP) minimum required version: 4.0.0
- Programming language: C
- Associated parts: All PSoC™ 6 MCU 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™ 6 Wi-Fi Bluetooth® prototyping kit (
CY8CPROTO-062-4343W) – Default value ofTARGET - PSoC™ 6 Wi-Fi Bluetooth® pioneer kit (
CY8CKIT-062-WIFI-BT) - PSoC™ 6 Bluetooth® LE pioneer kit (
CY8CKIT-062-BLE) - PSoC™ 6 Bluetooth® LE prototyping kit (
CY8CPROTO-063-BLE) - PSoC™ 62S2 Wi-Fi Bluetooth® pioneer kit (
CY8CKIT-062S2-43012) - PSoC™ 64 "Secure Boot" Wi-Fi Bluetooth® pioneer kit (
CY8CKIT-064B0S2-4343W) - PSoC™ 62S4 pioneer kit (
CY8CKIT-062S4) - PSoC™ 62S2 evaluation kit (
CY8CEVAL-062S2,CY8CEVAL-062S2-LAI-4373M2,CY8CEVAL-062S2-MUR-43439M2,CY8CEVAL-062S2-LAI-43439M2)
You need a third-party module - Pmod I2S2: stereo audio input and output to properly run this application. You need to manually wire the following connections:
| I2S signal | Kit pins | Pmod IS2S pins |
|---|---|---|
| TX_SCK | P9[2] | J1.3 |
| TX_DATA | P9[0] | J1.4 |
| TX_WS | P9[3] | J1.2 |
| MCLK | See the Table-1 | J1.1 |
| GND | GND | GND |
| VCC | V3.3 | VCC |
See Table 1 to determine the MCLK pin for the respective kits:
Table 1: MCLK_PIN selection for different targets
| Kit | MCLK_PIN |
|---|---|
| CY8CPROTO-062-4343W | P5 [6] |
| CY8CKIT-062-WIFI-BT | P5 [6] |
| CY8CKIT-062-BLE | P5 [6] |
| CY8CPROTO-063-BLE | P5 [6] |
| CY8CKIT-062S2-43012 | P5 [6] |
| CY8CKIT-064B0S2-4343W | P5 [6] |
| CY8CKIT-062S4 | P5 [6] |
| CY8CEVAL-062S2 | P5 [6] |
| CY8CEVAL-062S2-LAI-4373M2 | P5 [6] |
| CY8CEVAL-062S2-MUR-43439M2 | P5 [6] |
| CY8CEVAL-062S2-LAI-43439M2 | P5 [6] |
Note: Only Port 9 and Port 8 support smart I/O; this means that the I2S master can be placed only on pins 0–3 of these two ports. Note the following when using these connections:
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On PSoC™ 6 Bluetooth® LE pioneer kit (CY8CKIT-062-BLE), add a zero-ohm resistor at R131.
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On PSoC™ 6 Wi-Fi Bluetooth® pioneer kit (CY8CKIT-062-WIFI-BT), add a zero-ohm resistor at R162.
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On PSoC™ 62S4 pioneer kit (CY8CKIT-062S4), remove resistor R68 and add a zero-ohm resistor at R135.
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On PSoC™ 62S2 evaluation kit (CY8CEVAL-062S2), disconnect zero-ohm resistor from R100 and connect to R104.
Note: The PSoC™ 6 Bluetooth® LE pioneer kit (CY8CKIT-062-BLE) and the PSoC™ 6 Wi-Fi Bluetooth® pioneer kit (CY8CKIT-062-WIFI-BT) 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".
This example requires no additional software or tools.
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.
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(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}/docs_{version}/mt_ide_user_guide.pdf).
In command-line interface (CLI)
ModusToolbox™ software provides the Project Creator as both a GUI tool and 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.
The "project-creator-cli" 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 clones the "mtb-example-psoc6-smartio-i2s" application with the desired name "SmartIoI2S" configured for the CY8CKIT-062-WIFI-BT BSP into the specified working directory, C:/mtb_projects:
project-creator-cli --board-id CY8CKIT-062-WIFI-BT --app-id mtb-example-psoc6-smartio-i2s --user-app-name SmartIoI2S --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).
To work with a different supported kit later, use the Library Manager to choose the BSP for the supported kit. You can invoke the Library Manager GUI tool from the terminal using make library-manager command or use the Library Manager CLI tool "library-manager-cli" to change the BSP.
The "library-manager-cli" tool has the following arguments:
| Argument | Description | Required/optional |
|---|---|---|
--add-bsp-name |
Name of the BSP that should be added to the application | Required |
--set-active-bsp |
Name of the BSP that should be as active BSP for the application | Required |
--add-bsp-version |
Specify the version of the BSP that should be added to the application if you do not wish to use the latest from manifest | Optional |
--add-bsp-location |
Specify the location of the BSP (local/shared) if you prefer to add the BSP in a shared path | Optional |
The following example adds the CY8CPROTO-062-4343W BSP to the already created application and makes it the active BSP for the app:
~/ModusToolbox/tools_3.0/library-manager/library-manager-cli --project "C:/mtb_projects/SmartIoI2S" --add-bsp-name CY8CPROTO-062-4343W --add-bsp-version "latest-v4.X" --add-bsp-location "local"
~/ModusToolbox/tools_3.0/library-manager/library-manager-cli --project "C:/mtb_projects/SmartIoI2S" --set-active-bsp APP_CY8CPROTO-062-4343W
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.
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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).
If using a PSoC™ 64 "Secure" MCU kit (like CY8CKIT-064B0S2-4343W), the PSoC™ 64 device must be provisioned with keys and policies before being programmed. Follow the instructions in the "Secure Boot" SDK user guide to provision the device. If the kit is already provisioned, copy-paste the keys and policy folder to the application folder.
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Connect the board to your PC using the provided USB cable through the KitProg3 USB connector.
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Ensure that the
MCLK_PINmacro is assigned the value mentioned in Table 1 for the respective kits. -
Connect a speaker or headphone to the Pmod I2S2 audio jack (green connector).
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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 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, the application starts automatically. Press the user button to play the short audio "PSoC™ Rocks".
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 design provides middleware files (i2s_master.c/h) to implement the I2S master (Tx only). It requires an SPI resource and smart I/O. All the initialization of these blocks are handled by the middleware. You need to configure only the clocks and pin assignment for the SPI and smart I/O.
The I2S Interface timing diagram is shown below. It streams audio data for two channels - left and right. The Word Select (WS) signal indicates the channel that is currently streaming.
Figure 1. I2S timing diagram (from I2S Bus spec)
Due to the similarities to the SPI interface, you can leverage the SPI master to generate the clock (SCK) and the data signal (SD). The WS signal can be derived from the SPI-SS signal; however, it needs to keep toggling on every channel. In this implementation, the I2S channel length is 32 bits. Smart I/O is configured to toggle the WS signal every 32 cycles of SCK. It initially toggles when the SPI-SS signal asserts (beginning of transmission). Because the PSoC™ 6 SPI can support data width up to 16 bits only, the SPI FIFO needs to be written twice for every I2S channel.
Table 1. SPI and SGPIO mapping
| SPI signal | I2S signal | Description |
|---|---|---|
| SCLK | TX_SCK (SCK) | Clock driven by the I2S master |
| MOSI | TX_DATA (SD) | Data driven by the I2S master |
| SS | TX_WS (WS) | Indicates which channel transmits |
The clock that drives the I2S/SPI depends on the required frame rate. Typical frame rate values are 8/16/22.05/32/44.1/48 kHz. The formula to calculate the clock frequency based on the required frame rate is:
In this implementation, the channel length is fixed to 32 and SPI oversample is fixed to 4.
Usually an audio codec requires a master clock (MCLK). In this case, a PWM is used to generate MCLK. This clock is usually 256x faster than the frame rate (see the audio codec's datasheet).
Table 2 shows a quick summary of frequencies to be configured in the system for a given frame rate:
Table 2. SPI and SGPIO mapping
| Frame rate | I2S SCK | SPI clock | MCLK | Peripheral clock |
|---|---|---|---|---|
| 8 kHz | 0.512 MHz | 2.048 MHz | 2.048 MHz | 4.096 MHz |
| 16 kHz | 1.024 MHz | 4.096 MHz | 4.096 MHz | 16.384 MHz |
| 22.05 kHz | 1.4112 MHz | 5.6448 MHz | 5.6448 MHz | 22.5792 MHz |
| 32 kHz | 2.048 MHz | 8.192 MHz | 8.192 MHz | 32.768 MHz |
| 44.1 kHz | 2.822 MHz | 11.2896 MHz | 11.2896 MHz | 45.1584 MHz |
| 48 kHz | 3.072 MHz | 12.288 MHz | 12.288 MHz | 49.152 MHz |
In this example, the PLL is configured to source the CPU clocks (HFCLK0) and be 3x the peripheral clock. This examples uses the 16-kHz frame rate.
The firmware is designed to play a short audio record place in flash (wave.h/c) when the kit's button is pressed.
The I2S master init function requires an SPI resource and a smart I/O resource as arguments. The SPI resource is configured to generate an interrupt when the FIFO is half full. When the I2S master write function is invoked, it writes data to the SPI FIFO until it is full. Once the FIFO level drops to half, it triggers the interrupt and more data is written to the FIFO. The firmware also registers a callback to be executed when the I2S Write operation finishes.
The smart I/O resource is configured to translate the SPI-SS to I2S-WS signal. It uses the internal LUTs and data unit (DU) to count 32 cycles of the SPI-SCLK, and then toggle the I2S-WS output. It also delays the SPI-MOSI line to match the I2S bit arrangement.
Table 3. Application resources
| Resource | Alias/object | Purpose |
|---|---|---|
| SCB (SPI) (PDL) | SPI_I2S | Simulates the I2S master |
| Smart I/O (PDL) | SMARTIO | Used by the I2S master middleware to translate SPI to I2S |
| GPIO (HAL) | CYBSP_USER_BTN | User button |
| GPIO (HAL) | CYBSP_USER_LED | User LED |
| PWM (HAL) | mclk_pwm | Generates the MCLK for the audio codec |
| Resources | Links |
|---|---|
| Application notes | AN228571 – Getting started with PSoC™ 6 MCU on ModusToolbox™ software AN215656 – PSoC™ 6 MCU: Dual-CPU system design |
| Code examples | Using ModusToolbox™ software on GitHub |
| Device documentation | PSoC™ 6 MCU datasheets PSoC™ 6 technical reference manuals |
| Development kits | Select your kits from the evaluation board finder |
| 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. |
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 Developer community.
Document title: CE231443 – PSoC™ 6 MCU: Smart I/O I2S master
| Version | Description of change |
|---|---|
| 1.0.0 | New code example |
| 1.1.0 | Updated to support ModusToolbox software v2.3. Added support for CY8CKIT-062S4 |
| 1.2.0 | Added support for CY8CEVAL-062S2, CY8CEVAL-062S2-LAI-4373M2 |
| 1.3.0 | Removed target specific macros from the source code |
| 2.0.0 | Major update to support ModusToolbox™ v3.0. This version is not backward compatible with previous versions of ModusToolbox™ |
| 2.1.0 | Added support for CY8CEVAL-062S2-MUR-43439M2, CY8CEVAL-062S2-LAI-43439M2 and corrected pin assignments for MCLK on all BSPs |
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