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TIC12400-Q1: Does TIC12400-Q1/10024-Q1 have a functionality to latch IN_STAT_COMP until the bits are read?

Adam Torma
Mastermind 45340 points
Part Number: TIC12400-Q1
Other Parts Discussed in Thread: TIC12400

e2e,

Our customer would like to use MSDI in their system of powertrain. /INT signal is used for awakening up the MCU. The signal for awakening up the MCU is from several inputs such as an ignition switch or any other internal causes. They would like to distinguish where the signal comes from. However, the system has a MCU that needs few hundreds milliseconds to wake up. Some signals last for a few milliseconds. If the signal ends before the MCU READs INT_STAT_COMP bits, the MCU cannot distinguish what the interruption is.

 

Thank you,

Adam

  • 0
    TI__Expert 6395 points

    The TIC12400 does not latch the status of the INX pins once the interrupt is generated.  The IN_STAT_COMP register will always reflect the latest status of the pins at the end of the polling cycle.  

    If the MCU does not wake up before the status changes AND a new polling cycle runs, it could miss a switch status change.  The TIC12400 has ways to prevent this, such as increasing the polling cycle time to be longer than the MCU wake up time to ensure that a new cycle cannot begin before the MCU wakes up.

    Regards,

    Andrew

  • 0 in reply to Andrew_Mason
    TI__Intellectual 2000 points

    Hello Andrew_Mason,

    If the tPOLL_TIME is much longer than the time for pushing switch, can TIC12400 miss the switch-state change in polling mode?

    Regards,
    RYO

  • 0 in reply to RYO
    TI__Expert 6395 points
    Hello RYO,

    That is possible. You will have to find a balance between switch detection time, the MCU wake up time and the desired current consumption.

    Depending on the system default state the current consumption benefits typically start to fall off around 32 ms polling time. The EVM GUI has a current consumption calculator that can help with this as well to get a rough idea of the current consumption trade offs with polling time.

    Hope this helps,
    Andrew