Advantages of a USB Protocol Analyzer

Protocol analyzers

USB protocol analyzers come in two basic types: software-only analyzers and hardware-based analyzers

While software USB analyzers are sometimes cheaper than their hardware-based relatives, Total Phase offers hardware analyzers at competitive prices.
To understand what Total Phase's USB hardware-based analyzers do better than software analyzers, it is important to first understand how a software analyzer works.

Software USB analyzers replace the USB software stack on the host computer under test to monitor USB data. You are then completely disconnected from the hardware of the host PC (i.e. the host to be tested

Controllers) depends on which USB information is available for analysis. The host controller is responsible for arbitrating the data flow and also manages activities such as data retransmission in the event of errors. These functions are managed internally in the host controller and are therefore outside the remit of USB software analyzers.

What are the advantages of using a hardware analyzer over a software analyzer?

Non-intrusively monitor USB

By being independent of the system under analysis, the Beagle USB analyzers have no effect on the bus they monitor. In contrast, software analyzers are dependent on the actual hardware of the host computer, even if they replace the USB software stack.

Timing resolution at the nanosecond level

The Beagle USB Analyzers can provide accurate time stamping of USB traffic with an accuracy of nanoseconds. Software analyzers depend on the timing accuracy of the host operating system, which is thousands of times less accurate than that of a dedicated hardware analyzer.

See low-level USB bus states and error states

Because software analyzers are inherently kept in the dark by the host controller hardware, they cannot display bus states and low-level events such as
High-speed negotiation (K / J chirping)
Reset, pause and resume events
IN / NAKs, PING / NAKs, SOF
Transmission errors and retransmissions
and more...

Devices other than the analysis PC

Monitoring By their nature, software analyzers can only monitor USB traffic on the host computer. You cannot collect data between any USB host and a device. For example, software analyzers cannot eavesdrop on USB On-The-Go (OTG) events between devices such as a digital camera and a cell phone. Since most USB software analyzers are only compatible with Microsoft Windows, they are not suitable for debugging embedded hosts.

Monitor suspend & resume

The suspend & resume functionality of USB devices can only be properly monitored with a hardware analyzer. It is not possible to monitor these events with a software analyzer if the computer on which the application is running must be stopped.