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TPS25750: Operation of I2Cs with and without I2Cm

naohiko_nakamura
Prodigy 40 points
Part Number: TPS25750

Dear TI team.

We have connected the MPU to the I2Cs of the TPS25750 for I2C communication.
To make the TPS25750 work by itself, I implemented an EEPROM containing configuration data to the I2Cm of the TPS25750.
Then, I2Cs communication between the MPU and the TPS25750 became impossible.
Is this behavior normal?
(Is it a specification that only one of I2Cs and I2Cm communication of TPS25750 can be used?)

Best Regards,

  • 0
    TI__Mastermind 37855 points

    Hello Nakamura-san,

    I have assigned this thread to Chris T.

    Please give us a couple days to respond.

    Thanks and Regards,

    Chris L.

  • 0 in reply to Christopher Lim1
    TI__Genius 12905 points

    Nakamura-san,

    It is not a specification that one can be used at a time. I do not know why I2Cs is not working anymore but some things to check:

    Is I2Cs SCL/SDA pulled up by LDO_3V3? 

    Is LDO_3V3 at 3.3V?

    Is VIN_3V3 at 3.3V?

    Do you see I2C communication on I2Cs? 

    Sweep possible TPS25750 addresses (0x20, 0x21, 0x22, 0x23)

    Thanks,

    Chris 

  • 0 in reply to Christodulos Tsongas
    Prodigy 40 points

    Thanks, Chris!
    The I2C SCL/SDA is pulled up by LDO_3V3.
    I will measure the voltages on I2C_LDO and VIN_3V3.
    I2C communication for I2Cs is done, but I do not know if the setting is complete.
    Do you know what command should be issued to indicate completion?

  • 0 in reply to naohiko_nakamura
    TI__Genius 12905 points

    Nakamura-san,

    naohiko_nakamura said:
    I2C communication for I2Cs is done

    Do you mean I2Cs is working? 

    naohiko_nakamura said:
    but I do not know if the setting is complete.

    What settings are you talking about?

    naohiko_nakamura said:
    Do you know what command should be issued to indicate completion?

    Simply reading-back the 0x03 register would be best. 0x03 register is 4 bytes.

  • 0 in reply to Christodulos Tsongas
    Prodigy 40 points

    Thank you Chris,

    Do you mean I2Cs is working? 

    →Sorry, I made a mistake, it is I2Cm, not I2Cs.

  • 0 in reply to naohiko_nakamura
    Prodigy 40 points

    Thank you Chris,

    Do you mean I2Cs is working? 

    →Sorry, I made a mistake, it is I2Cm, not I2Cs.

    My mistake seems to be confusing you and I will explain again the current situation.
    Attached is my circuit configuration.
    For I2Cs, there are no devices connected other than the MPU and the TPS25750.
    For I2Cm, there are no devices connected other than EEPROM and TPS25750.
    5V and 3.3V on the schematic are supplied from the power supply IC on the same board.
    Both VIN_3V3 and LDO_3V3 were 3.3V.
    I2Cs communication is possible or not depending on whether EEPROM is mounted or not.

    [Question 1] If the setting data in the EEPROM is incorrect, can I2Cs be used?
    [Question 2] Are there any conditions such as LDO3V3 must not be used as a pull-up power supply for I2Cm?

  • +1 in reply to naohiko_nakamura
    TI__Genius 12905 points
    naohiko_nakamura said:
    [Question 1] If the setting data in the EEPROM is incorrect, can I2Cs be used?

    No the I2Cs interface is always setup. I cannot help further on this without log captures of the I2Cs interface. You can also load your configuration into a EVM and see if results are different.

    naohiko_nakamura said:
    [Question 2] Are there any conditions such as LDO3V3 must not be used as a pull-up power supply for I2Cm?

    Some but they are rarely seen. There is no reason to use other pull-up power supplies. 

  • 0 in reply to Christodulos Tsongas
    Prodigy 40 points

    Thanks Chris,

    I found out why I2Cs cannot communicate with my configuration.
    The cause was that I was using 3.3V power supply instead of LDO3V3 as pull-up power supply for I2Cs.
    After changing the pull-up power supply of I2Cs to LDO3V3 as a trial, I2C communication of I2Cs became possible,
    The return value of I2Cs 0x03 register became "0x04 0x41 0x50 0x50 0x20".
    This can be read as 'APP' mode, so it appears that the TPS25750 is correctly loading the configuration data from the EEPROM.
    Thank you for your support!