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Original question:

TCA6408 & PCA9534 Interrupt issue

PCA9534A: Resetting of Interrupt for PCA9534A

KARTHIK KRISHNA JAYACHANDRAN
Intellectual 380 points
Part Number: PCA9534A

Hello,

In the data sheet, page number:16 it was mentioned that "Resetting the interrupt circuit is achieved when data on the port is changed to the original setting, data is read from the port that generated the interrupt."

What does original settings mean?  

  • +1
    Guru 310880 points

    The original setting is the input state at the time when the port was last read.

    For example, assume that the input is low, and that you read the port. Now the interrupt is disabled. If the input goes high, the interrupt activates. If the input then goes low again before the port has been read, the interrupt is deactiveated.

    This means that a short pulse on some input will result only in a short pulse on the interrupt output, and that you might not be able to detect on which pin it happened.