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AM335x PMIC I2C communication

Stefano Bisi
Intellectual 460 points
Other Parts Discussed in Thread: TPS65217

Goodmorning

on SWCU093B user guide PMIC TPS65910Ax is wired to I2C_0 port of AM335x Processor.

This connection is mandatory ? Or I can connect  PMIC to another I2C port ? I.E. I2C_2 Port ?

Thank in advance

Stefano

  • 0
    TI__Guru**** 393215 points
    Hi Stefano,
     
    Yes it is. If you connect to another I2C port you will face an enormous task of modifying power management software. I'm not even sure whether this is possible (I seem to remember that M3 firmware is provided as binary).
  • 0 in reply to Biser Gatchev-XID
    Intellectual 460 points

    Hi Biser

    thank you for fast reply; I'm not sure it's M3 which talks to PMIC using I2C_0 since starterware\bootloader contains a source file for A8 which initializes PMIC.

    My question is : does on chip A8 bootloader use I2C_0 before secondary external bootloader does ? Or does M3 really talks using I2C  0 ?

    We are a bit confused since in none manual this topic is explained.

    Stefano

  • 0 in reply to Stefano Bisi
    TI__Guru**** 393215 points
    Hi Stefano,
     
    I found a previous thread on M3 and this is what it says: "The M3 is in AM335x for managing power management functions and it tightly coupled with the PRCM.  It was not intended to be generally programmable...."
     
    If you plan to use Starterware there is a separate forum for it: http://e2e.ti.com/support/embedded/starterware/default.aspx, where you can ask this. However there is another point: I2C0 is on the Wakeup power domain, which is the main reason for it being used for PMIC control, I think.
  • 0 in reply to Biser Gatchev-XID
    Prodigy 215 points

    Hi all,

    In our design the only I2C available to interface to PMIC is the I2C1. We have these constraints from PinMux due other resources we needed (2 UARTs, 2 RMII, etc).

    We do not need the wake up behavior for our application.  The are assuming that the default settings of TPS65217 are enough to power up the AM335X.  After AM335X have powered up we may chance some settings of TPS65217 (through I2C1).

    Questions:

    1) Considering the scenario we described above, is it possible to use I2C1 for PMIC ?

    2) I would not expect so much impact in software due to use I2C1 instead of I2C0. Am I wrong?

    Many thanks

    Rodrigo

  • 0 in reply to Rodrigo Aznar Mendes
    TI__Guru**** 393215 points
    If you don't intend to use SmartReflex and plan to work on a fixed OPP only, it could be possible.