Data Center Software Series: Understanding the Bus Pane

The Data Center Software is Total Phase’s free bus monitoring software that is used in conjunction with the line of Beagle Protocol Analyzers, Komodo CAN Duo Interface, USB Power Delivery Analyzer, and Promira Serial Platform with the eSPI Analysis Application. This software provides an interface that is used to capture, monitor, and debug I2C, SPI, USB, USB Power Delivery, CAN, and eSPI communication between devices in real time. Additionally, it allows engineers to gather valuable insights into their embedded systems, providing various details about the devices under test and captured data, including low-level bus events, enumeration details, packet data, bus errors, and much more.

The Data Center Software includes numerous tools within the interface that allow users to review important details regarding the devices and bus data; one of them being the Bus Pane. In this article, we’ll provide an overview of the Bus Pane and how it can be used to gather important information about the bus under test.

About the Bus Pane

The Bus Pane is found in the Navigator window of the Data Center Software and shows the devices that have been detected on the serial bus. It provides detailed device information including addresses, configurations, and endpoint descriptors. Users can view the number of packets and bytes sent and received in real time. The Bus Pane also provides Statistics and Enumeration details of the devices and bus transactions.

Using the Bus Tree

In the Navigator window, I2C, SPI, USB, USB Power Delivery, CAN, and eSPI devices that are detected on the bus are displayed and distinguished by the device IDs or addresses. For SPI devices, all the traffic is lumped into one device per capture since the Beagle I2C/SPI Protocol Analyzer can only monitor one slave select at a time. When performing a simultaneous USB 3.0/2.0 capture, separate bus trees are available for USB 2.0 and USB 3.0 because both buses exists separately, but in parallel.

Bus Pane Data Center Software Example of the Bus Pane

By clicking and expanding a device, a hierarchy of descriptor information will be revealed, including configuration, interface, and endpoint descriptors. Clicking on any level of the tree will show a parsed view of those descriptors and any child descriptors.

The Transactions and Bytes columns list the number of each that have been sent or received from each endpoint, interface, configuration, and entire device.

Right-clicking in the Bus tree will reveal a pop-up menu that gives the user the option to apply a filter so that specific devices can be shown or hidden in the Transaction window. This menu provides the following options:

  • Filter: Show Only - Only show records of the selected category.
  • Filter: All Except - Only show records that are not part of the selected category. (Bus Pane Only)
  • Filter: Disable - Disable the active filter.
  • Find First - Find the first instance for the selected category. (Statistics Pane Only)
  • Find Last - Find the last instance for the selected category. (Statistics Pane Only)
  • Fully Collapse Branch - Collapse the current branch from the selected element down.
  • Fully Expand Branch - Expand the current branch from the selected element down.
  • Expand All - Expand the entire statistics tree.
  • Collapse All - Collapse the entire statistics tree.

This content menu also includes a Manage Configs option where users can manage the configuration information for the device and/or apply a new configuration.

Manage Configs Data Center Software Manage Configs Option in Pop-up Menu

Additionally, users can click on a packet in the Transaction window and the related device will be highlighted in the Bus pane.

Statistics Details

The Statistics Pane provides a real-time count of packets, errors, and other protocol specific constructs as data is being captured. The Statistics Pane is tied to the Bus Pane. When a bus is selected in the Bus Pane, the aggregate of the bus-level data and the bus connected devices data will be displayed in the statistics table. When a device or endpoint is selected, only its data will be displayed.

When the individual statistics are expanded in the Statistics Pane, the sub data will vary, presenting data counts of subcategories of the expanded statistic. If a particular statistic is available for a device and a bus is selected in the Bus Pane, expanding the bottom node of the tree will display data counts for its internal devices.

The Statistic column provides a hierarchical view of all the statistics available. The Available column provides a count of the total number of packets, transfers, and events counted during the capture. If a filter is applied, the Visible column shows the number of packets, transfers, and errors that match the current filter.

By using the Previous and Next buttons, users can quickly jump to a statistic of interest by selecting the category in the Statistics Pane.

Additionally, to download the statistics information for further review, users can click the Save button to save the statistics from the Stats Pane in semicolon-delimited CSV format.

Below are bus statistics that are captured for I2C, SPI, USB, USB Power Delivery, CAN, and eSPI communication.

SPI Statistics Bus Pane SPI Bus Statistics Details
I2C Statistics Bus Pane I2C Bus Statistics Details

CAN Bus A Statistics Bus Pane CAN Bus A Statistics Details
CAN Bus B Statistics Bus Pane CAN Bus B Statistics Details

 

USB 2.0 Statistics Bus Pane USB 2.0 Statistics Details
USB 3.0 Statistics Bus Pane USB 3.0 Statistics Details

 

eSPI Statistics Bus Pane eSPI Bus Statistics Details
USB Power Delivery Statistics Bus Pane USB Power Delivery Statistics Details

 

Enumeration Details

For USB, once devices undergo the entire enumeration sequence, the descriptor information for these devices will be displayed in the Bus Pane. If a capture is stopped prematurely or interrupted, it could result in missing or incomplete descriptor information. In these cases, it is possible to manually apply a device configuration to the device.

For a summary of the descriptor information on specific devices, users can click on the device in the Bus Pane and the Enumeration tab will provide a summary of details for that device. Here, users can view information including the device details, VID, PID, and configurations.

In this example, we can see the device descriptor details for a USB Flash drive:

Enumeration Tab Bus Pane Example of Enumeration Tab

The Bus Pane in the Data Center Software is a helpful feature for debugging bus communication as it provides insight into the devices detected on the bus and allows users to easily filter for specific devices and its correlating data. This feature also summarizes relevant device descriptor information and other bus statistics that can be useful when analyzing and interpreting the data. For more information on this functionality or the Data Center Software and other Total Phase tools, please contact us at sales@totalphase.com.