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TMP411 / clear the state of the #ALERT pin

K.Yaita
Guru 29710 points
Other Parts Discussed in Thread: TMP411

Hi Team,

My customer considers to use ALERT mode(AL/TH bit = 0) for TMP411.
I believe an SMBus alert response address command(00011001) must be used to clear the ALERT pin.
Is there another method to clear the ALERT pin?

I heard my customer's system is I2C(not to SMBus) and he couldn't use SMBus Alert command.

Best Regards,
Yaita

  • 0
    TI__Mastermind 30600 points

    Hi Yaita,

     

    There are three ways to clear the AL pin, the method you mentioned is one of them:

     

    (1)    GENERAL CALL RESET - Send Two-Wire General Call command 06h (0000 0110b) to address 00h (0000 0000b). TMP411 executes a software reset. This software reset restores the power-on reset state to all TMP411 registers, aborts any conversion in progress, and clears the ALERT and THERM pins. This command resets all slave devices on the bus.

    (2)    SMBus Alert command (00011001) – it is the same for I2C. If the ALERT pin of the TMP411 is active, it becomes inactive at the completion of the SMBus Alert command. If there are multiple slave devices on the bus and more than one device responds to SMBus Alert command, there is going to be arbitration, TMP411 AL pin may or may not resets depending on whether it wins the arbitration.

    (3)    Master reads the device address, as long as the condition that caused the alert no longer persists(over or under limits), and the Status Register has been reset, the ALERT pin resets.

     

    Regard, Guang

    Apps-Sensing Products

  • 0 in reply to Guang Zhou
    Guru 29710 points

    Hi Guang-san,

    Thank you for your reply!

    >(3)    Master reads the device address, as long as the condition that caused the alert no longer persists(over or under limits),
    >and the Status Register has been reset, the ALERT pin resets.

    Is "reads the device address" the same in meaning as "read  Status Register(pointer address 02h)"?
    My customer confirmed it but he couldn't see the ALERT pin resets, so I would like to confirm.

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Mastermind 30600 points

    Hi Yaita-san,

     

    I believe you are correct.

     

    First make sure the condition that triggered the warning in the first place has been corrected, reset the corresponding warning bits in the Status register and then issue a read command. The register pointer in the read command can be any register pointer, not necessarily has to be the Status register. The Alert pin should reset.

     

    This is my understanding, and I’ll do some research to confirm.

     

    Regard, Guang

    Apps-Sensing Products

  • 0 in reply to Guang Zhou
    Guru 29710 points

    Hi Guang-san,

    My customer confirmed the Alert pin function to set "Local Temparature High Limiｔ" register lower than actual and check Alert pin went "Low", after that he set back the register value.
    And then, he confirmed [D7:D0] of status register went all "0"(read status register), but Alert pin couldn't reset(keep "Low" state).



    I really appreciate if you research to confirm.

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Mastermind 30600 points

    Hi Yaita-san,

     

    It turns out there are only two ways you can reset the ALERT pin, GCR and SMBUS Alert reset. The third one I initially mentioned is a misunderstanding on my part, my apologies.

     

    SMBUS Alert reset command is the right way to go.

     

    Regard, Guang

    Apps-Sensing Products

  • 0 in reply to Guang Zhou
    Guru 29710 points

    Hi Team,

    Thank you for your research.

    However, Datasheet page.20 shows the following.



    I can't catch the meaning of "ALERT resets when the master reads the device address".
    Is it typo?

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Mastermind 30600 points

    Hi Yaita-san,

     

    The sentence you quoted indeed is confusing. It really should have been replaced with “SMbus Alert Reset command”.

     

    Regard, Guang

    Apps-Sensing Products

  • 0 in reply to Guang Zhou
    Guru 29710 points

    Hi Guang-san,

    Thank you for your reply.
    Could you modify the datasheet?
    My customer required it.

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Mastermind 30600 points

    Hi Yaita-san,

     

    We are in the process of revising data sheets, I’ll check where TMP411 fits on the list of "to-do", and make sure this issue gets addressed in the next revision.

     

    Regard, Guang

    Apps-Sensing Products

     

  • 0 in reply to Guang Zhou
    Guru 29710 points

    Hi Guang-san,

    I appreciate for your support.

    Best Regards,
    Yaita