This example demonstrates how to set up the USB block of an Infineon MCU using the audio class of Segger's emUSB-Device middleware to implement an audio recorder. It is currently supported on PSoC™ 6 MCU. This code example uses digital microphones with the pulse density modulation (PDM) to pulse code modulation (PCM) converter hardware block. Audio data captured by the microphones is streamed over USB to a PC using the audio device class. An audio recorder software tool, such as Audacity, running on a computer initiates the recording and streaming of audio data.
Figure 1. Block diagram
The PDM/PCM interface requires two wires - PDM Clock and PDM Data. Up to two digital PDM microphones can share the same PDM data line. One microphone samples in the falling edge and the other on the rising edge.
Provide feedback on this code example.
- ModusToolbox™ v3.2 or later (tested with v3.2)
- Board support package (BSP) minimum required version: 4.0.0
- Programming language: C
- Associated parts: All PSoC™ 6 MCU parts
- GNU Arm® Embedded Compiler v11.3.1 (
GCC_ARM) – Default value ofTOOLCHAIN - Arm® Compiler v6.16 (
ARM) - IAR C/C++ Compiler v9.40.2 (
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™ 62S2 Wi-Fi Bluetooth® Pioneer Kit (
CY8CKIT-062S2-43012) - PSoC™ 62S1 Wi-Fi Bluetooth® Pioneer Kit (
CYW9P62S1-43438EVB-01) - PSoC™ 62S1 Wi-Fi Bluetooth® Pioneer Kit (
CYW9P62S1-43012EVB-01) - PSoC™ 62S2 Evaluation Kit (
CY8CEVAL-062S2,CY8CEVAL-062S2-LAI-4373M2,CY8CEVAL-062S2-MUR-43439M2,CY8CEVAL-062S2-LAI-43439M2,CY8CEVAL-062S2-MUR-4373EM2,CY8CEVAL-062S2-MUR-4373M2,CY8CEVAL-062S2-CYW43022CUB)
This code example requires a PDM microphone. If using an Arduino-compatible kit, you can use the TFT display shield board CY8CKIT-028-TFT, which has a PDM microphone. This shield comes with CY8CKIT-062-WIFI-BT kit. It can also be purchased standalone and be used with other supported kits listed.
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. 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 If you do not upgrade, you will see an error like "unable to find CMSIS-DAP device" or "KitProg firmware is out of date".
See the ModusToolbox™ tools package installation guide for information about installing and configuring the tools package.
Install a terminal emulator if you don't have one. Instructions in this document use Tera Term.
This example uses the Audacity tool to stream the audio recording from Infineon MCU detected as microphone. You can also use any other software tool that is able to stream audio data.
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 "emUSB-Device: Audio device" application with the desired name "USBAudioDevice" configured for the CY8CPROTO-062-4343W BSP into the specified working directory, C:/mtb_projects:
project-creator-cli --board-id CY8CPROTO-062-4343W --app-id mtb-example-usb-device-audio-freertos --user-app-name USBAudioDevice --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 board to your Windows computer 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
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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. Confirm that the title of the code example is displayed on the serial terminal and the kit user LED keeps blinking until the USB cable is plugged to the USB device connector.
Figure 2. USB audio device startup
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Connect another USB cable to the USB device connector (see the kit user guide for its location). If using the CY8CKIT-062-WIFI-BT or any other Arduino-compatible kit, ensure the TFT shield is connected to the main board.
-
On the Windows computer, verify that a new USB device is enumerated as a microphone and named as "USB audio recorder".
Figure 3. USB audio device enumeration
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Note that the kit user LED is turned OFF and a USB audio device connected status is displayed on the serial terminal as shown in Figure 4.
Figure 4. USB audio device connected
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Open an audio recorder software tool in the computer. If you do not have one, download the open-source software Audacity. Make sure to select the correct microphone in the audio recorder tool as shown in Figure 5.
Figure 5. Microphone on Audacity
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Start a recording session in the audio recorder software and play a sound, or speak over the microphone in the kit. Subsequently the kit user LED is turned ON indicating that the device has started recording.
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To exercise the microphone's mute control, open the Control Panel from Windows Start menu and double-click on the Sound menu in it. In the Sound window, navigate to the Recording tab and select the detected Microphone (Audio Control).
-
Double-click the selected Microphone (Audio Control) to open its properties. In the Microphone Properties window, toggle the Mute
button under the Levels tab to mute/unmute the microphone.Figure 6. USB audio device mute
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Stop the recording session and play it to confirm that the audio was recorded correctly. Also observe that the kit user LED is turned OFF indicating the end of recording session.
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Once the USB cable gets disconnected from the USB device, USB audio device disconnected status is displayed on the serial terminal as shown in Figure 7.
Figure 7. USB audio device disconnected
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 ofmain(). 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 ofmain(). See KBA231071 to learn about this and for the workaround.
In other IDEs
Follow the instructions in your preferred IDE.
The PDM/PCM hardware block can sample one or two PDM digital microphones. In this application, the hardware block is configured to sample stereo audio at 4 ksps (default) with 16-bits resolution. The sample audio data is eventually transferred to the USB data endpoint buffer.
- This example can support audio sampling rate up to 44.1 ksps on PSoC™ 6. Because when the USB host and PSoC™ 6 audio subsystem are out of sync, the PDM/PCM block can generate variable number of bytes (196/188) at every 1 ms to be sent to the USB host. If all the bytes are not sent, the PDM/PCM FIFO will eventually overflow or underflow, causing disruption in the audio streaming to the USB host. As the ISO transfer is limited to 192-bytes in the PSoC™ 6 driver, variable number of bytes generated by the audio subsystem cannot be transferred at audio sample rate greater than or equal to 48 ksps with 16-bits resolution.
Note: This limitation is not applicable for DMA driver.
- You can change the sample frequencies by generating the “USB audio design” files by useing the example (.uad) files provided in 'configs' folder and include it in application. For more information see, USB Audio Device Generator tool section.
- The USB descriptor implements the audio device class with one endpoint:
- Audio IN Endpoint: Sends the data to the USB host
The firmware consists of a main() function which creates an "Audio App Task". This task invokes audio_class_init_data() function to add the audio interface to USB stack. It configures the device descriptor for enumeration using USBD_SetDeviceInfo() API. Once the configuration is done, "Audio App Task" calls audio_in_init() function to initialize the PDM PCM block. At the end it creates the "Audio In Task" and calls the target API USBD_Start() to start the USB stack. This task keeps track of the USB connection/disconnection events by monitoring the suspend and resume conditions on the bus.
The application has DMA enabled by default. Follow these steps to disable the DMA feature and ensure that the application functions without DMA:
- Remove the
USBD_ENABLE_DMAfrom the DEFINE variable in the Makefile. - Disable all DMA DataWire in the DMA tab from the device configurator.
- Turn off all DMA channel for endpoints in the USB personality from the device configurator.
- Disable the 'Enable DMA mode' in the USB personality from the device configurator.
A microphone configuration must be defined by creating an “USB audio design” file (extension .uad). This file specifies all characteristics of the audio device and is converted by the USBAudioDeviceGenerator.exe tool into a C source file and a C header file, that should be used to build the audio application. The tool provided in emUSB-Device middleware library. For more details, see Section 17.2 from emUSB-Device User Guide & Reference Manual.
The /configs/Microphone_configs_48kHz files contains the default audio configuration for the application and also provides the USB audio design file (Microphone_configs_48kHz.uad).
The USB Audio Device Generator tool is a command-line tool that can be invoked from a command shell:
USBAudioDeviceGenerator.exe [-s] [-o=<output-file>] <USB-audio-design-file>
-s = Silent execution (except for errors).
-o = Base name for the generated .c and .h files.
If not specified, the name of the USB audio design file is used.
Table 1. Application resources
| Resource | Alias/object | Purpose |
|---|---|---|
| USBDEV (HAL) | CYBSP_EMUSB_DEV | USB device block configured with audio descriptor |
| UART (HAL) | CYBSP_DEBUG_UART_TX, CYBSP_DEBUG_UART_RX | UART Tx and Rx pins used by Retarget-IO for printing on the console |
| GPIO (HAL) | CYBSP_USER_LED | User LED is turned ON when audio is recorded |
| PDM/PCM (HAL) | pdm_pcm | Interfaces with the microphone |
| Resources | Links |
|---|---|
| Application notes | AN228571 – Getting started with PSoC™ 6 MCU on ModusToolbox™ AN215656 – PSoC™ 6 MCU: Dual-CPU system design |
| Code examples | Using ModusToolbox™ 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 – 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 | emUSB-Device – emUSB-Device emUSB-Device API reference – emUSB-Device API Reference psoc6-middleware – Links to all PSoC™ 6 MCU middleware |
| 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: CE236785 - emUSB-Device: Audio recorder
| Version | Description of change |
|---|---|
| 1.0.0 | New code example |
| 2.0.0 | Updated to support ModusToolbox™ v3.2 Updated to support new audio class and DMA Added support for CY8CEVAL-062S2-MUR-4373EM2, CY8CEVAL-062S2-MUR-4373M2, and CY8CEVAL-062S2-CYW43022CUB kits |
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