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TCA9539: Several questions

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Part Number: TCA9539

Hi all

Would you mind if we ask TCA9539?

<Question1>
When we set OUTPUT0 and OUTPUT1 in a row, we assume that we need configure as follows;
-Command Byte=0x02
-To write OUTPUT0 and OUTPUT1 in a row
Is our recognition correct? 

<Question2>
There is the desription on the datasheet P16.
"The TCA9539 open-drain interrupt (INT) output is activated when any input state differs from its corresponding Input Port register state and is used to indicate to the system master that an input state has changed."

We could understand active timing of /INT(active low), however what timing does /INT return to Hiz?
On the Figure 33 and Figure34, it shows /INT timing.
Does it mean /INT return to Hiz after reading corresponding outputX? 


Kind regards,

Hirotaka Matsumoto

  • Hello Hirotaka-san,

    Hirotaka Matsumoto


    <Question1>
    When we set OUTPUT0 and OUTPUT1 in a row, we assume that we need configure as follows;
    -Command Byte=0x02
    -To write OUTPUT0 and OUTPUT1 in a row
    Is our recognition correct?

    [Bobby] This is correct.

    <Question2>
    There is the desription on the datasheet P16.
    "The TCA9539 open-drain interrupt (INT) output is activated when any input state differs from its corresponding Input Port register state and is used to indicate to the system master that an input state has changed."

    We could understand active timing of /INT(active low), however what timing does /INT return to Hiz?

    [Bobby] Two 'OR' condition: If input returns back to it's previously remembered state OR you perform a read on the input ports.


    On the Figure 33 and Figure34, it shows /INT timing.
    Does it mean /INT return to Hiz after reading corresponding outputX? 

    [Bobby] Correct, After the ACK on reading a port, the device will take in the current value of the input port as the new "remembered state" and deassert the INT (INT goes HI-Z).


    Kind regards,

    Hirotaka Matsumoto

    Please see my comments above in GREEN.

    -Bobby