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Linux/TMP411: Does a SMB timeout reset the whole device with all registers or is only the SMBus affected?

Thomas Stadtherr
Prodigy 20 points
Part Number: TMP411

Tool/software: Linux

We intend to use the TMP411E, which should be fully register and pin compatible with the ADT7461. Because of the SMB, there is a minimum SCL frequency of 1kHz, otherwise a timeout will be caused, which resets the device. When we set the two maximum temperature registers, we dont't intend to access the SMBus afterwards, so there will be no more SCL clock on the device. If we don't disable the timeout function, this will cause a reset condition. The question is now: does this exclusively reset the SMBus or does this reset affect  the whole device including all registers like e.g. the maximum temperature regs? When only resetting the SMBus, this would be a great feature to prevent the device from "hanging" when a non finished frame had occoured.

  • 0
    TI__Mastermind 35895 points
    Thomas,

    SMBus timeout does not reset the contents of the registers.

    Idling the bus will not cause an SMBus timeout. An SMBus timeout occurs when the I2C Master stops communication unexpectedly. In the event that communication stops while the sensor is responding with a logic low, it will let go of the bus after the 30ms timeout. This prevents the bus from being locked up until power cycle, which would be the case in an explicitly I2C implementation.

    Thanks,
    Ren
  • 0 in reply to Ren Schackmann
    Prodigy 20 points
    Hello Ren,
    this is exactly what I hoped to hear.
    Thank you very much.
    Thomas