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Question from the Customer:

I have a snippet of transaction log from an EEPROM I2C read on the bus. There are some symbols that I do not understand – can you explain them to me?

For example,  (2015-12-14 15:46:04) [S] <54:w>* [P]

I guess this means [S] Start condition, write to 0x54, and ends with a [P] Stop condition. What does * mean? Also, can you give me some insight on the bus activity in line 07 and 08 below?

01 (2015-12-14 15:46:04) [S] <54:w> 08 c8 01 [P]

02 (2015-12-14 15:46:04) [S] <54:w>* [P]

03 (2015-12-14 15:46:04) [S] <54:w>* [P]

04 (2015-12-14 15:46:04) [S] <54:w> 08 c9 01 [P]

05 (2015-12-14 15:46:04) [S] <54:w>* [P]

06 (2015-12-14 15:46:04) [S] <54:w>* [P]

07 (2015-12-14 15:46:04) [S] <54:w> 08 ca 00 [P]

08 (2015-12-14 15:46:04) [S] <54:w> 08 cb 00 [P]

09 (2015-12-14 15:46:04) [S] <54:w>* [P]

10 (2015-12-14 15:46:04) [S] <54:w>* [P]

Response from Technical Support:Thanks for your questions! Here are the definitions of the symbols:

• S is start bit.
• P is stop bit.
• W is write.
• R is read.
• In the I2C data column, NACK’ed bytes are followed by an asterisk (*) to differentiate them from ACK’ed bytes.
• In the I2C address column, an asterisk (*) following the address indicates that the address byte was NACK’ed.

Please note - Aardvark I2C monitoring is a legacy feature that works only up to 125 KHz and is no longer supported by current versions of the Control Center Software.  For optimized and full-featured I2C analysis up to 4 MHz and SPI analysis up to 24 MHz, we offer the Beagle I2C/SPI Protocol Analyzer.

Combined with the Data Center Software, it shows NACK indications, and more robust I2C monitoring features,

• Monitor I2C up to 4 MHz
• Monitor SPI up to 24 MHz
• Real -Time Data Capture
• LiveSearch and LiveFilter
• 20 ns resolution for bit-level timing

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

• Aardvark I2C/SPI Host Adapter User Manual

• Beagle Protocol Analyzer User Manual

• Data Center Software User Manual

• Control Center Serial Software User Manual

If you have other questions about our host adapters or other Total Phase products, feel free to email us at sales@totalphase.com, or if you already own one of our devices and have a technical question, please submit a request for technical support.