I need to capture high-speed eSPI traffic, what do you recommend?

Question from the Customer:

I’m trying to monitor eSPI traffic at 48 MHz. However, the method I’m currently using degrades the eSPI signals.  To get clean signals, the bus had to be slowed down to 8MHz before it was reliable again. Unfortunately, that does not support the functionalities that I need to verify and support.

In addition, I want to monitor at least two sideband signals along with the traffic. I see this option should be available with your Promira Serial Platform and eSPI Analysis Application – how is that done?

I have one last question about connecting to the system under test (SUT). I am concerned that attaching the 34-pin cable that comes with the Promira platform could degrade the eSPI signal. Do you have any other cables you could recommend to minimize the impact of attaching the analyzer to the bus?

Response from Technical Support:

Thanks for your questions! The Promira Serial Platform with the eSPI Analysis Application can monitor communication between an eSPI master and slaves up to 66 MHz with support for single, dual and quad I/O.  It works with our Data Center Software to stream all of the eSPI bus data to your PC in real time.

Promira Serial Platform eSPI Analysis Application

About sidebands - you can use the Virtual Wire channel to communicate the state of sideband pins or GPIO tunneled through eSPI as in-band messages. The Promira platform has 11 digital IO signals that can be configured as input or output signals.

  • Digital input supports inserting events into the data stream.
  • Digital output supports matching certain events as well as sending output to other devices, such as oscilloscopes.

This allows you to synchronize events (such as a Virtual wire channel transaction) on the bus with other signals you may be measuring. A digital input event (falling edge or rising edge) can trigger a capture. Digital output behavior can be configured as set low, set high, toggle from initially low to high, or toggle from initially high to low.

In addition, an eSPI Simple Match can also trigger a capture. A capture event can toggle a digital output pin for detecting a Virtual wire channel transaction. To simplify capturing data with filters and triggers, take a look at the Data Center Software.  If you choose to work with Promira API software, we also provide eSPI Active Example Files.

For signal integrity, the cable we provide is only 6 inches long to minimize signal degradation. We have other cables that can be purchased separately:

Additionally, the Promira platform allows for flexible cabling, meaning you can create a custom cable to fit your specific needs and attach it to the Promira hardware without opening the case.

We hope this answers your question. Additional resources that you may find helpful include the following:

More questions? More projects? You can contact us and request a demo that applies to your application, as well as ask questions about the Promira Serial Platform and other Total Phase products.

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