USB Vendor Bulk Echo Example

Table of Contents

• Introduction
• Supported Combinations
• Steps to Run the Example
  • Build the example
  • HW Setup
    • AM261x-LP
  • Run the example
    • Install WinUSB Driver (Windows)
    • Verify Enumeration
• Testing the Example
  • Prerequisites
    • 1. Install PyUSB
    • 2. Download libusb
  • Running the Script
• See Also

Introduction

This example is a USB device Vendor class application based on TinyUSB.

The example does the below

• Initializes the TinyUSB USB core driver and Vendor class.
• Exposes a vendor-specific bulk endpoint pair (IN and OUT) to the USB host.
• Any data sent by the USB host on the OUT endpoint is echoed back on the IN endpoint.

Supported Combinations

Parameter	Value
CPU + OS	r5fss0-0_nortos
	r5fss0-0_freertos
Toolchain	ti-arm-clang
Board	am261x-lp
Example folder	examples/usb/device/vendor_bulk_echo

Steps to Run the Example

Build the example

• When using CCS projects to build, import the CCS project for the required combination and build it using the CCS project menu (see Using SDK with CCS Projects).
• When using makefiles to build, note the required combination and build using make command (see Using SDK with Makefiles)

Note

SysConfig will generate an empty ti_usb_descriptor.c for this example. The actual USB descriptors are provided by usb_descriptors.c which is part of the example source.

HW Setup

AM261x-LP

• To test the application, use a Windows PC as a USB host.
• Connect the J10 (Micro B USB Device connector) on AM261x-LP to the USB host.

USB Micro B Device Connector (J10)

Run the example

• Launch a CCS debug session and run the executable, see CCS Launch, Load and Run

Install WinUSB Driver (Windows)

A vendor-specific USB device has no built-in OS driver. On first connection, Windows will show the device as Unknown device in Device Manager.

Unknown device shown in Device Manager

To communicate with the device, install the WinUSB driver using the Zadig tool:

1. Download Zadig from: https://github.com/pbatard/libwdi/releases/download/v1.4.1/zadig-2.7.exe
2. With the example running on the board and the USB cable connected, open Zadig.
3. Click Options → List All Devices.
4. Select Unknown Device #1 (or the equivalent entry) from the dropdown.

Selecting the Unknown Device in Zadig

1. Ensure WinUSB is selected as the target driver, then click Install Driver.

Note

The board must be running the example while using Zadig; otherwise the device may not appear.

Verify Enumeration

After driver installation:

1. Terminate the debug session in CCS.
2. Power-cycle the board.
3. Restart the debug session.

The device should now appear as AM261x Vendor under Universal Serial Bus devices in Device Manager.

AM261x Vendor device enumerated correctly

Testing the Example

A Python test script is provided in the SDK to verify the bulk echo functionality:

tools/usb_test_scripts/usb_vendor_bulk_echo_test.py

The script sends three bulk transfer payloads of increasing size (128 KB, 256 KB, 512 KB) to the device and verifies that the echoed data matches exactly. It reports the result, elapsed time, and throughput for each test.

Prerequisites

1. Install PyUSB

Install the PyUSB library using pip:

pip install pyusb

2. Download libusb

PyUSB requires the libusb backend DLL on Windows.

• Download the latest libusb Windows release from: https://github.com/libusb/libusb/releases
• Extract the archive and locate libusb-1.0.dll under VS2019\MS64\dll\ (for 64-bit systems).
• Place libusb-1.0.dll in the same directory as the test script:

    tools/usb_test_scripts/libusb-1.0.dll
  

Note

If your libusb-1.0.dll is in a different location, update the LIBUSB_DLL_PATH variable at the top of the script accordingly.

Running the Script

With the example running on the board and the USB cable connected, run:

python usb_vendor_bulk_echo_test.py

If all tests pass, the output should look as follows:

Expected test output when all bulk transfer tests pass

See Also

USB