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TCA6424A: Interrupt self-clearing on "data on the port changed to the original setting"

Maxim Adelman
Prodigy 30 points
Part Number: TCA6424A

I'd like to understand how exactly does the interrupt self-clear on the input change. I.e., what is meant by "resetting the interrupt circuit is achieved when data on the port is changed to the original setting". For one thing, there is no "data" on the port - there is a voltage level. But furthermore, what exactly is the "original setting"? The description is similar in the TC6416A datasheet, so I presume the question applies to that as well.

Experimentally, looking on the IO Expander EVM (http://www.ti.com/tool/IO-EXPANDER-EVM

  • 0
    Prodigy 30 points
    The posting was cut off for some reason. Continuing below:

    ---

    I observe the following:

    1. With all ports configured as inputs and toggle switches in input mode, interrupt is held high. If I depress a toggle switch, interrupt goes low. If I then release a toggle switch, it goes high.

    2. If I read the input register while holding a toggle switch, interrupt will go high. Then if I release the toggle switch, it will go low again. If I hold the button again, it will go high again, and so on.

    I.e., my interpretation of this is interrupt is cleared if the input signal returns to the level it was at immediately prior to the last edge that caused the interrupt to be asserted. Please confirm that this is indeed the case.
  • 0 in reply to Maxim Adelman
    TI__Guru 62910 points
    Maxim,

    Glad you were able to find the answer! If you have any other questions on the device please don't hesitate to start a new thread.

    Regards,
    Max