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TPS65987D: Any differences in I2C1 and I2C3 for master?

Brian Antheunisse
Expert 5305 points
Part Number: TPS65987D
Other Parts Discussed in Thread: TPS65987, BQ25703

 Hi guys,

One thing I’ve noticed that is different between the eval board and reference design, and the hardware design guide and the I2C guideline doc, is that the design guide and document both indicate that I2C1 should be used as a slave connected to the embedded controller; I2C2 should be reserved for use with a Thunderbolt controller; and I2C3 should be used as a master to control I2C slave devices such as the mux, battery charger, etc.

 

However, this is not how the eval board or the ref design use the I2C ports. In the BQ25703/TPS65987 ref design, I2C port 1 is used as the master to control the battery charger. I2C ports 2 and 3 are not connected to anything, it seems.

 

In the eval board, I2C1 is used as the master for the on-board slaves; I2C2 is the slave connected to the FTDI controller; and I2C3 is not used (although it is possible to swap the I2C1 and I2C3 connections to the expansion pack connector if desired.)

 

It’s not a big deal, since the ports can be configured in different ways (except for I2C2.)  I’m just curious why TI made these boards and didn’t follow their own recommendations for how to use the TPS65987 I2C ports. I’m wondering if there is something we should know about the ports that maybe didn’t show up in the hardware guide or programming guide.

Thanks!

Brian

  • 0
    TI__Mastermind 36756 points

    Hi Brian,

    In systems where all 3 I2C ports need to be used, it is best to follow the datasheet recommendation. However, in the case of the TPS65987EVM and the TIDA-01627, only 1 or 2 of the I2C ports were needed. Since I2C1 and I2C3 can be I2C masters, these were used for testing that functionality. I2C2 on the TPS65987EVM goes to the FTDI as I2C2 is a slave only port.

    If this answers your question, PLEASE select This resolved my issue

    Thank you,
    Eric