emUSB-Device: Quad USB to UART bridge

This sample program showcases the implementation of the USB Bulk device class to create four USB-UART bridges utilizing PSoC™ 6. Upon enumeration, the program presents itself as four Bulk interfaces on a PC. Each UART corresponds to a Bulk interface (for example, UART0 mapped to Bulk Interface 0). Any data transmitted via the Bulk interface will be seen on the corresponding UART port TX pin, while any data received through the MCU's UART RX pin will be seen on the corresponding Bulk Interface.

View this README on GitHub.

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Requirements

• ModusToolbox™ v3.1 or later (tested with v3.1)
• 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 v11.3.1 (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™ 62S2 Wi-Fi Bluetooth® Pioneer Kit (CY8CKIT-062S2-43012) - Default value of TARGET
• PSoC™ 6 Wi-Fi Bluetooth® Prototyping Kit (CY8CPROTO-062-4343W)
• PSoC™ 6 Wi-Fi Bluetooth® Pioneer Kit (CY8CKIT-062-WIFI-BT)
• PSoC™ 62S1 Wi-Fi Bluetooth® Pioneer Kit (CYW9P62S1-43438EVB-01)
• PSoC™ 62S2 Wi-Fi Bluetooth® Prototyping Kit (CY8CPROTO-062S2-43439)
• 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. 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 If you do not upgrade, you will see an error like "unable to find CMSIS-DAP device" or "KitProg firmware is out of date".

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

The ModusToolbox™ tools package provides the Project Creator as both a GUI tool and a command line tool.

Use Project Creator GUI

1. 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).

2. 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.

3. 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 "quad-uart-bridge" application with the desired name "uad-uart-bridge" configured for the CY8CKIT-062S2-43012 BSP into the specified working directory, C:/mtb_projects:

project-creator-cli --board-id CY8CKIT-062S2-43012 --app-id mtb-example-usb-device-quad-uart-bridge --user-app-name quad-uart-bridge --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 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™ install directory}/docs_{version}/mtb_user_guide.pdf).

Open the project

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).

Operation

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.

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

   1. Select the application project in the Project Explorer.

   2. 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 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-Device: Quad USB to UART bridge application" is displayed on the UART terminal.

   Figure 1. KitProg3 Terminal

   

5. Connect another USB cable from your PC (or reuse the same cable used to program the kit) to the DEVICE USB connector (see the kit user guide for its location, this is not the same USB port used for programming).

6. If the Bulk USB device is successfully enumerated by the PC, Orange LED (LED8) will become solid otherwise it will blinks.

7. Four UART has to be configured using the GPIOs for each kit. Below table details GPIOs configured as UART for CY8CKIT-062S2-43012 kit and for other supported kits refer UART Pin configuration for supported kits section.

   UART	Pin	MUC IO	EVK jumper pin
   UART 0	RX	P0[2]	J22.1 (IO0)
   UART 0	TX	PO[3]	J22.2 (IO1)
   UART 1	RX	P10[0]	J2.1 (A0)
   UART 1	TX	P10[1]	J2.2 (A1)
   UART 2	RX	P5[4]	J4.5 (D4)
   UART 2	TX	P5[5]	J4.6 (D5)
   UART 3	RX	P13[4]	J22.6 (IO5)
   UART 3	TX	P13[5]	J22.7 (IO6)

8. Connect four USB-to-UART modules to all four UART Ports. You can use any USB-to-UART modules, such as MiniProg4 from another kit, to connect to UART ports. Ensure that the UART TX pin is connected to RX pin of USB-to-UART module.

9. Serial port parameters for all four UARTs are set to 8N1 and 115200 baud.

10. Open all four UART ports using serial terminal application like 'Tera Term'. If the connection is right, below message will be seen on terminal app.

Figure 2. UART Terminals

11. Open all four Bulk Interface COM ports using serial terminal application like 'Tera Term'. If the Bulk Interface COM ports are not getting detected follow the steps detailed in the Installing the USB driver section.
12. You can start writing in any one UART terminal application and you can see the same text in corresponding USB Bulk terminal and vice-versa.

Note: The example shown in Figure 3 illustrates the terminal output for UART 0 and Bulk Interface 0.

Figure 3. Terminal Output for UART0

13. You can use Hercules terminal app to send & receive long txt file to verify the data communication with long data files.

UART Pin configuration for supported kits

Kit	UART 0 (RX)	UART 0 (TX)	UART 1 (RX)	UART 1 (TX)	UART 2 (RX)	UART 2 (TX)	UART 3 (RX)	UART 3 (TX)
CY8CKIT-062S2-43012	P0[2]	P0[3]	P10[0]	P10[1]	P5[4]	P5[5]	P13[4]	P13[5]
CY8CPROTO-062-4343W	P9[0]	P9[1]	P10[0]	P10[1]	P5[4]	P5[5]	P13[4]	P13[5]
CY8CKIT-062-WIFI-BT	P12[0]	P12[1]	P10[0]	P10[1]	P9[0]	P9[1]	P6[0]	P6[1]
CYW9P62S1-43438EVB-01	P0[2]	P0[3]	P10[0]	P10[1]	P9[0]	P9[1]	P6[0]	P6[1]
CY8CPROTO-062S2-43439	P10[0]	P10[1]	P9[0]	P9[1]	P5[4]	P5[5]	P13[4]	P13[5]
CY8CEVAL-062S2	P10[0]	P10[1]	P9[0]	P9[1]	P6[0]	P6[1]	P5[4]	P5[5]
CY8CEVAL-062S2-LAI-4373M2	P10[0]	P10[1]	P9[0]	P9[1]	P6[0]	P6[1]	P5[4]	P5[5]
CY8CEVAL-062S2-MUR-43439M2	P10[0]	P10[1]	P9[0]	P9[1]	P6[0]	P6[1]	P5[4]	P5[5]
CY8CEVAL-062S2-LAI-43439M2	P10[0]	P10[1]	P9[0]	P9[1]	P6[0]	P6[1]	P5[4]	P5[5]

Debugging

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 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.

In other IDEs

Follow the instructions in your preferred IDE.

## Design and implementation This document provides details on how the Quad Serial USB to UART example project for PSoC™ 62 (CY8CKIT-062S2-43012) is implemented.

This sample program showcases the implementation of the USB Bulk device class to create four USB-UART bridges utilizing PSoC™ 6. Upon enumeration, the program presents itself as four Bulk interfaces on a PC. Each UART corresponds to a Bulk interface, Ex. UART0 mapped to Bulk Interface 0. Any data transmitted via the Bulk interface will be seen on the corresponding UART port TX pin, while any data received through the MCU's UART RX pin will be seen on the corresponding Bulk Interface.

Figure 1. Architecture diagram

The TX state machine is responsible to handle the packets received from the USB to the UART. The following figure shows the state machine diagram:

Figure 2. TX State Machine diagram

States	Function
Idle state	No packet in process
Receive state	Moves the data from the USB buffer to the UART Tx buffer
Send state	Initiates the UART Tx transmission

The RX state machine is responsible to handle the packets received from the UART to the USB. The following figure shows the state machine diagram:

Figure 3. RX State Machine diagram

States	Function
Idle state	No packet in process
Receive state	Moves the data from the UART Rx buffer to the USB Tx buffer
Send state	Send the UART data over the USB. If all data size is smaller than buffer size, goes to the IDLE state. If the data size is bigger than the buffer size, goes to the Send More state. If the data size is equal to the buffer size, goes to the Send Zero Packet state.
Send more	Send the remaining bytes from the buffer. countRx is equal to the remaining bytes.
Send zero packet	Sends a null packet with no data. This is required when the total number of bytes to be send is multiple of the buffer size.

Installing the USB driver

This USB interface can be used with WinUSB, LibUSB or USB Serial (CDC) driver. But we have tested with USB Serial (CDC) driver. Follow below steps to install USB Serial (CDC) driver in Windows 10 or above.

1. Open the Device Manager. If the driver is not installed the USB device will be detected as four unknown devices or USB bulk devices.

   

2. Download and install Zadig tool from this Link.

3. Open Zadig and choose Options > List all devices. This will show all USB devices along with the four unknown devices.

4. Install the USB Serial(CDC) driver for all four interfaces.

5. Unplug and plug the USB cable again and check device manager. If the drivers are successfully installed four Bulk Interfaces will be appears under Port (COM & LPT) devices in the device managers.

   

Related resources

Resources	Links
Application notes	AN228571 – Getting started with PSoC™ 6 MCU on ModusToolbox™ AN215656 – PSoC™ 6 MCU: Dual-CPU system design AN79953 – Getting started with PSoC™ 4 AN85951 – PSoC™ 4 and PSoC™ 6 MCU CAPSENSE™ design guide
Code examples	Using ModusToolbox™ on GitHub
Device documentation	PSoC™ 6 MCU datasheets PSoC™ 6 technical reference manuals PSoC™ 4 datasheets PSoC™ 4 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 mtb-pdl-cat2 – PSoC™ 4 Peripheral Driver Library (PDL) mtb-hal-cat2 – Hardware Abstraction Layer (HAL) library
Middleware on GitHub	capsense – CAPSENSE™ library and documents 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.

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.

Document history

Document title: CE237944 - emUSB-Device: Quad USB to UART bridge

Version	Description of change
1.0.0	New code example
1.0.1	README Update

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