emUSB Host: CDC echo application

This code example shows how to set up an Infineon MCU's USB block as a communication device class (CDC) host using the emUSB-Host middleware. It implements echo functionality from the host side and requires a USB device configured to echo the CDC signals back to the host. This example is currently supported on PSoC™ 6 MCU.

View this README on GitHub.

Provide feedback on this code example.

Requirements

• 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

Supported toolchains (make variable 'TOOLCHAIN')

• GNU Arm® embedded compiler v10.3.1 (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™ 6 Wi-Fi Bluetooth® pioneer kit (CY8CKIT-062-WIFI-BT) – Default value of TARGET
• PSoC™ 62S2 Wi-Fi Bluetooth® pioneer kit (CY8CKIT-062S2-43012)
• PSoC™ 62S1 Wi-Fi Bluetooth® pioneer kit (CYW9P62S1-43438EVB-01)
• PSoC™ 62S2 evaluation kit (CY8CEVAL-062S2, CY8CEVAL-062S2-LAI-4373M2, CY8CEVAL-062S2-MUR-43439M2, CY8CEVAL-062S2-LAI-43439M2)

Hardware setup

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

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 If you do not upgrade, you will see an error like "unable to find CMSIS-DAP device" or "KitProg firmware is out of date".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 code example programs the target as a USB host with a CDC Echo functionality. An external USB device with CDC echo functionality is required for the demonstration of the USB host capability. An already configured CDC echo device is used or refer to the USB CDC device echo code example for configuring an Infineon MCU device with USB CDC echo functionality.

Software setup

Install a terminal emulator if you don't have one. Instructions in this document use Tera Term.

This example requires no additional software or tools.

Using the code example

Create the project and open it using one of the following:

In Eclipse IDE for ModusToolbox™ software

1. Click the New Application link in the Quick Panel (or, use File > New > ModusToolbox™ Application). This launches the Project Creator tool.

2. 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.

3. In the Project Creator - Select Application dialog, choose the example by enabling the checkbox.

4. (Optional) Change the suggested New Application Name.

5. 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.

6. 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 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.

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-usb-host-cdc-echo" application with the desired name "USB-host-CDC" 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-usb-host-cdc-echo --user-app-name USB-host-CDC --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™ tools package 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

Following example adds the CY8CKIT-062-WIFI-BT BSP to the already created application and makes it the active BSP for the app:

library-manager-cli --project "C:/mtb_projects/USB-host-CDC" --add-bsp-name CY8CKIT-062-WIFI-BT --add-bsp-version "latest-v4.X" --add-bsp-location "local"

library-manager-cli --project "C:/mtb_projects/USB-host-CDC" --set-active-bsp APP_CY8CKIT-062-WIFI-BT

In third-party IDEs

Use one of the following options:

• Use the standalone Project Creator tool:

  1. Launch Project Creator from the Windows Start menu or from {ModusToolbox™ software install directory}/tools_{version}/project-creator/project-creator.exe.

  2. In the initial Choose Board Support Package screen, select the BSP, and click Next.

  3. In the Select Application screen, select the appropriate IDE from the Target IDE drop-down menu.

  4. Click Create and follow the instructions printed in the bottom pane to import or open the exported project in the respective IDE.

• Use command-line interface (CLI):

  1. Follow the instructions from the In command-line interface (CLI) section to create the application.

  2. Export the application to a supported IDE using the make <ide> command.

  3. Follow the instructions displayed in the terminal to create or import the application as an IDE project.

For a list of supported IDEs and more details, see the "Exporting to IDEs" section of the ModusToolbox™ tools package user guide (locally available at {ModusToolbox™ software install directory}/docs_{version}/mtb_user_guide.pdf).

Note: For enabling/disabling power in VBUS line, ensure defining the following macro in usbh_config.c for the corresponding kit in use.

Table 1. Macro for enabling/disabling power in VBUS line

Kit	Macro	Pin_number
CY8CKIT-062-WIFI-BT	USBH_POWER_CONTROL_PIN	P13_2
CY8CKIT-062S2-43012	USBH_POWER_CONTROL_PIN	P1_2
CYW9P62S1-43438EVB-01	USBH_POWER_CONTROL_PIN	P1_2

Operation

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

2. Open a terminal program and select the KitProg3 COM port. Set the serial port parameters to 8N1 and 115200 baud.

3. Program the board using one of the following:

   Using Eclipse IDE for ModusToolbox™ software

   1. Select the application project in the Project Explorer.

   2. In the Quick Panel, scroll down, and click <Application Name> Program (KitProg3_MiniProg4).

   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
   

4. After programming, the application starts automatically. Confirm that "emUSB Host: CDC Echo Application" is displayed on the UART terminal.

   Figure 1. Terminal output on program startup

   

5. The user LED blinks slowly to indicate a wait state. The USB host waits to connect with a USB device.

6. Use a USB cable to conect the USB CDC echo device to the kit's USB host port(see the kit user guide for its location). Note: Kits that are used as USB device and has USB Micro-B connector on it will require an external power via the board's kitprog port.The user must connect the OTG cable to host kits which has Micro-B connector. Note that when CY8CKIT-062-WIFI-BT kit is used as a host and the kits which are used as a USB device for communication, need not be powered through kitprog port.

Refer to the USB CDC device echo code example for configuring an Infineon MCU (currently supported on PSoC™ 6) with USB CDC echo functionality.

7. When connected, the host acknowledges the addition of a USB CDC device, enumerates it and starts the echo using the communication device class (CDC). The USB host sends a data packet at every 5 seconds containing the device details like VendorId and ProductId, as well as the data stream that is sent and received.

   Figure 2. USB device connected

   

8. The USB device echoes the data stream back to the host to demonstrate the CDC echo functionality. The packets are continuously sent and received until the physical connection via the cable is disconnected.

   Figure 3. USB device disconnected

   

9. For disconnection, if the USB device needs external power, first remove the Kitprog connection powering the kit and then disconnect the device kit from the host kit. The USB host stops the communication, acknowledges the removal of the USB device as shown in Figure 3 and returns to the wait state until another USB device is connected to start the echo communication.

Debugging

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.

Design and implementation

This code example uses the FreeRTOS on the CM4 CPU. The following tasks are created in main.c:

• USB host CDC task - Initializes and functions emUSB host stack
• USB host task - This task iterates over the list of active timers and invokes the registered callback functions in case the timer has expired.
• USB host ISR task - This task waits for events from the interrupt handler of the host controller and processes them.

The main function is responsible for initializing the device, ports and all other necessary peripherals. It creates the USB host CDC task usbh_cdc_task which is responsible for initializing the emUSB host middleware stack with CDC class.

The emUSB host stack utilizes two dedicated RTOS tasks. These tasks are created using FreeRTOS for this code example. The first task usbh_task is responsible for managing the internal software timers. It calls the target API USBH_Task() and also invokes the registered callback functions, if the timer runs out. The second task, usbh_isr_task calls the target API USBH_ISRTask(), processes the interrupts generated by the USB host controller and treats it as a highest priority.

The priorities of both tasks have to be higher than the priority of any other application task which uses emUSB host. For more information regarding the usage of emUSB host target APIs, refer to the emUSB host user guide (locally available at <mtb_shared>/emusb-host//docs)

The usbh_cdc_task() routine then sets the configuration flags and gets into a wait state requesting the status of the USB bus using the USBH_CDC_AddNotification target API and usb_device_notify application function. The USB host slowly blinks the user LED indicating to be in the wait state.

When a USB CDC device with echo functionality is connected to the host via a USB cable, the usb_device_notify application function sets a non-zero value for device_ready and the firmware then initiates device_task() which handles the echo communication. The device_task() routine retrieves the device information, enumerates and configures the CDC device to start the echo communication. It also configures the data packets that are sent by the host to the device. The USB host sends a string data packet using USBH_CDC_Write target API. The echo communication is successful when the USB CDC device echoes the packet back to the host. This is done using the USBH_CDC_Read target API. The host prints the logs accordingly on the terminal. The host waits for 5 seconds after which it re-initiates the echo communication to the USB device. This process continues until the USB device is physically disconnectes. When the device disconnectes, usb_device_notify application function sets a zero value for device_ready and the usbh_cdc_task() goes to the wait state till the next connection between the host and device occurs.

Figure 4. USB host CDC task flow diagram

Resources and settings

Table 2. Application resources

Resource	Alias/object	Purpose
USB (HAL)	usb_0_obj	USB host block configured with CDC Echo functionality
UART (HAL)	cy_retarget_io_uart_obj	UART HAL object used by Retarget-IO for Debug UART port
GPIO (HAL)	CYBSP_USER_LED	User LED

Related resources

Resources	Links
emUSB Host reference	emUSB Host - USB host stack for embedded applications
USB Implementers Forum	USB implementers forum - A non-profit organization created to promote and support USB
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 MCU 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	psoc6-middleware – Links to all PSoC™ 6 MCU middleware mqtt – MQTT client library and documents wifi-connection-manager – Wi-Fi connection manager (WCM) library and documents wifi-mw-core – Wi-Fi middleware core library and documents freeRTOS – FreeRTOS library and documents
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

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.

For PSoC™ 6 MCU devices, see How to design with PSoC™ 6 MCU - KBA223067 in the Infineon Developer community.

Document history

Document title: CE236486 - emUSB host: CDC echo application

Version	Description of change
1.0.0	New code example
1.1.0	Added support for CY8CKIT-062S2-43012, CYW9P62S1-43438EVB-01, CY8CEVAL-062S2, CY8CEVAL-062S2-LAI-4373M2, CY8CEVAL-062S2-MUR-43439M2, and CY8CEVAL-062S2-LAI-43439M2
1.2.0	Updated design.modus file for CY8CKIT-062-WIFI-BT, Readme.md

---

© Cypress Semiconductor Corporation, 2020-2023. This document is the property of Cypress Semiconductor Corporation, an Infineon Technologies company, and its affiliates ("Cypress"). This document, including any software or firmware included or referenced in this document ("Software"), is owned by Cypress under the intellectual property laws and treaties of the United States and other countries worldwide. Cypress reserves all rights under such laws and treaties and does not, except as specifically stated in this paragraph, grant any license under its patents, copyrights, trademarks, or other intellectual property rights. If the Software is not accompanied by a license agreement and you do not otherwise have a written agreement with Cypress governing the use of the Software, then Cypress hereby grants you a personal, non-exclusive, nontransferable license (without the right to sublicense) (1) under its copyright rights in the Software (a) for Software provided in source code form, to modify and reproduce the Software solely for use with Cypress hardware products, only internally within your organization, and (b) to distribute the Software in binary code form externally to end users (either directly or indirectly through resellers and distributors), solely for use on Cypress hardware product units, and (2) under those claims of Cypress’s patents that are infringed by the Software (as provided by Cypress, unmodified) to make, use, distribute, and import the Software solely for use with Cypress hardware products. Any other use, reproduction, modification, translation, or compilation of the Software is prohibited.
TO THE EXTENT PERMITTED BY APPLICABLE LAW, CYPRESS MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARD TO THIS DOCUMENT OR ANY SOFTWARE OR ACCOMPANYING HARDWARE, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. No computing device can be absolutely secure. Therefore, despite security measures implemented in Cypress hardware or software products, Cypress shall have no liability arising out of any security breach, such as unauthorized access to or use of a Cypress product. CYPRESS DOES NOT REPRESENT, WARRANT, OR GUARANTEE THAT CYPRESS PRODUCTS, OR SYSTEMS CREATED USING CYPRESS PRODUCTS, WILL BE FREE FROM CORRUPTION, ATTACK, VIRUSES, INTERFERENCE, HACKING, DATA LOSS OR THEFT, OR OTHER SECURITY INTRUSION (collectively, "Security Breach"). Cypress disclaims any liability relating to any Security Breach, and you shall and hereby do release Cypress from any claim, damage, or other liability arising from any Security Breach. In addition, the products described in these materials may contain design defects or errors known as errata which may cause the product to deviate from published specifications. To the extent permitted by applicable law, Cypress reserves the right to make changes to this document without further notice. Cypress does not assume any liability arising out of the application or use of any product or circuit described in this document. Any information provided in this document, including any sample design information or programming code, is provided only for reference purposes. It is the responsibility of the user of this document to properly design, program, and test the functionality and safety of any application made of this information and any resulting product. "High-Risk Device" means any device or system whose failure could cause personal injury, death, or property damage. Examples of High-Risk Devices are weapons, nuclear installations, surgical implants, and other medical devices. "Critical Component" means any component of a High-Risk Device whose failure to perform can be reasonably expected to cause, directly or indirectly, the failure of the High-Risk Device, or to affect its safety or effectiveness. Cypress is not liable, in whole or in part, and you shall and hereby do release Cypress from any claim, damage, or other liability arising from any use of a Cypress product as a Critical Component in a High-Risk Device. You shall indemnify and hold Cypress, including its affiliates, and its directors, officers, employees, agents, distributors, and assigns harmless from and against all claims, costs, damages, and expenses, arising out of any claim, including claims for product liability, personal injury or death, or property damage arising from any use of a Cypress product as a Critical Component in a High-Risk Device. Cypress products are not intended or authorized for use as a Critical Component in any High-Risk Device except to the limited extent that (i) Cypress’s published data sheet for the product explicitly states Cypress has qualified the product for use in a specific High-Risk Device, or (ii) Cypress has given you advance written authorization to use the product as a Critical Component in the specific High-Risk Device and you have signed a separate indemnification agreement.
Cypress, the Cypress logo, and combinations thereof, WICED, ModusToolbox, PSoC, CapSense, EZ-USB, F-RAM, and Traveo are trademarks or registered trademarks of Cypress or a subsidiary of Cypress in the United States or in other countries. For a more complete list of Cypress trademarks, visit www.infineon.com. Other names and brands may be claimed as property of their respective owners.