Support Question of the Week: Aardvark Multi-Purpose Host Adapter or Beagle Low-Cost Protocol Analyzer?

Q: I have an Aardvark I2C/SPI Host Adapter. I have been able to monitor I2C traffic up to approximately 300 kbps, but now I need to monitor at 400 kbps. Can I make Aardvark adapter work at this speed or are there other options?

A: Thanks for your question! The Aardvark I2C/SPI Host Adapter is a general-purpose I2C device with master and slave capabilities.  Although it is capable of some slower speed monitoring, it is no longer supported for that application. We recommend it for active communication on the bus as a master or slave.

Monitoring I2C traffic is a “legacy” feature of the Aardvark I2C/SPI Host Adapter. As an I2C host adapter the Aardvark adapter can operate at a maximum bit rate of 800 kbps as a master or slave. For SPI, the Aardvark adapter operates at bit rates up to 8 MHz as an SPI master and 4 MHz as an SPI slave. However, as an I2C protocol analyzer monitoring a device, the speed of the Aardvark adapter is limited to 125 kHz.

Aardvark I2C/SPI Host Adapter, multi-function device Figure 1: Aardvark I2C/SPI Host Adapter
  • The Aardvark adapter can continuously monitor I2C traffic up to 125 kHz. It may be possible to monitor higher bitrates for small transactions; however reliability is not guaranteed for this condition.
  • Once enabled, the I2C monitor automatically monitors the attached I2C bus and returns data back to the host asynchronously.

For monitoring I2C, we recommend using the Beagle I2C/SPI Protocol Analyzer. This low-cost protocol analyzer is a non-intrusive bus monitor, is more robust and much faster, and low-cost. This device should meet both your budget and technical requirements, and provide an excellent ROI (return of investment).

Beagle I2C/SPI Low-Cost Protocol Analyzer, p/n TP320121 Figure 2: Beagle I2C/SPI Low-Cost Protocol Analyzer

Following is a summary of the Beagle I2C/SPI Protocol Analyzer capabilities. For more details, please refer to the Beagle Protocol Analyzer Data Sheet.

  • Non-intrusively monitor I2C up to 4 MHz
  • Non-intrusively monitor SPI up to 24 MHz Note: This capture performance is dependent on CPU speed and SPI bus throughput.
  • Non-intrusively monitor MDIO up to 2.5 MHz (Clause 22 and Clause 45, IEEE RFC802.3.
  • Real-Time Data Capture.
  • Bit-level timing down to 20 ns resolution.

For easy use, we provide Data Center Software, which is free. This graphical user interface (GUI) interfaces with Beagle protocol analyzers, provides views of real-time capture, the ability to configure the capture mode and more. Example APIs are also available, which you can use as-is or modify for your use. Following are some documents that may interest you:

Product Selector Guide
Total Phase Protocol Analyzers
Beagle Protocol Analyzer Data Sheet
Data Center Software User's Manual

We hope this answers your question. If you have other questions about our Protocol Analyzers or other Total Phase products, feel free to email us at or

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