Decoding the I2C Bus Monitor (#MIIC-101) Log File FAQ (Frequently Asked Questions)

How do I decode the I2C/SMBus Monitor (#MIIC-101) Log File?

The ASCII Remote Select (page 24) of the I2C/SMBus Monitor (#MIIC-101) User's Guide has the protocol. For your convenience, the information is provided below.

Each I2C/SMBus event is coded into three ASCII character tokens. The first character is the token type. The last two characters is either the slave address for the first byte, or message data for the remaining bytes. The data in the stop token is always 00H, and is always followed with a carriage return.


    1- Start with Ack
    2- Start without Ack
    3- Data with Ack
    4- Data without Ack
    5- Stop
AA - 8-bit Slave Address (00...FFH) for Start tokens.
HH - 8-bit Data (00...FFH) for Data tokens.

Our parsers breaks a message into three character strings, then switch on the first character. The only exception is the <CR> at the end of each message. You may or may not want to wait for the carriage return, for if the bus locks up in the middle of a message, you may not get the Stop and carriage return.

Can't find the answer to your question here? Then e-mail your question to us at

I2C is just a mouse click away TM