Debug USB Faster with USB Class-Level Decoding

What are USB Classes?

One of the reasons for USB's popularity is the fact that any standard USB device will work immediately upon being plugged in to any host computer. USB classes make this possible. Groups of similar devices, like Mass Storage Devices and Human Interface Devices (HID), use a standard set of commands and instructions which allow them to share a common USB Class Driver.

What is USB Class-Level Decoding?

Class-level decoding is the translation of the low-level USB data into human-readable USB class-level commands and instructions. This powerful new feature in the Data Center Software makes debugging USB devices even easier. Simply start a capture, plug in a USB device to the Beagle USB 480 Protocol Analyzer, and the software will automatically parse raw packets into human-readable format, all in true real-time.

Here is a comparison between the protocol-level view and the class-level view.

Protocol-Level View The USB data from a Mass Storage device has been organized into packet groups. The data is in its raw format which is difficult to understand.

Class-Level View The USB traffic has been organized into hierarchical Mass Storage specific data groups. Now that the class-level data is decoded, it is easier to understand.

Supported Classes

The Data Center software supports all these classes and more.

Hub Hub Class Notification Human Interface Device (HID) HID Class Descriptor HID Class Request Audio v1.00 Audio Class Descriptor Audio Class Request Video (v1.0 - v1.1) Bulk Data Transfers PIMA 15740 Interpretation Event Interrupt Transfers Still Image (PTP) Bulk Data Transfers PIMA 15740 Interpretation Event Interrupt Transfers Device Firmware Update (DFU) DFU Class Requests DFU Class Descriptors

Mass Storage (Bulk Only) SCSI - MMC SCSI - SBC SCSI - SPC Printer Bulk Data Transfers Printer Class Descriptors Printer Class Requests Communications Device Class (CDC) Abstract Control Model Ethernet Networking Control Model Wireless Handset Control Model Network Control Model (NCM) Mobile Direct Line Model (MDLM) Semantic Models Early Network Control Model (ENCM) Support for more USB classes coming soon.

Features

Info and Data Panes The image to the right shows the USB traffic from a HID Device. The class-level data from a USB mouse has been decoded and the Info Pane at the far right displays the parsed class-level fields for easy viewing. When a field is highlighted in the Info Pane, the relevant portion of the data payload is highlighted in the Data Pane on the bottom. Benefits Class-level data is parsed into a human-readable format. Class-level fields in the data payload are clearly displayed.

Hierarchical Display In the transaction window, IN, OUT, and SETUP packet groups are automatically organized into class-level groupings. In the image to the left, class-level data from a USB Mass Storage Device has been organized into high-level commands. These commands are further organized into individual phases, such as Command Transport and Data Transport. Benefits Grouped class-level transactions are easier to analyze and debug. Switch instantly between class-level and protocol-level views with a single click.

Availability

• Full class-level decoding is supported for data captured by a Beagle USB 480 Protocol Analyzer.
• Descriptor parsing is supported for data captured by a Beagle USB 12 Protocol Analyzer.