• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 2 answers
  • Subscribers 34 subscribers
  • Views 348 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TCA9539-Q1: How to INT pin work？My measure shows INT is always low. It does not meet expectation

ling xinjie
Intellectual 325 points
Part Number: TCA9539-Q1
Other Parts Discussed in Thread: TCA9539

Tool/software:

Hi TI

I test TCA9539QPWRQ1 in my design，and I test INT is always low，in your datasheet shows when trigger a ACK，INT will be turn high，is there any dependency condition？

How to check weather my config is right？

  • 0
    Guru 316690 points

    You have to read the port that generated the interrupt. In general, you have to read both ports to be sure.

  • 0
    TI__Mastermind 47328 points

    Hi Ling,

    Like Clemens has stated, you must read the port that generated the interrupt in the first place. This means you should most likely read both INPUT ports to be sure (0x00 & 0x01). 

    Also, do you have a pull-up resistor connected from INT to VCC. /INT is an open-drain output, it needs a pull-up resistor for the HIGH logic state. 

    Regards,

    Tyler

  • 0 in reply to Tyler Townsend
    Intellectual 325 points

    Hi Tyler & Clemens

    Thanks for your help, I have been add pull up resistance.

    In my application，TCA9539 connect 16 channel input，and I want to monitor these ports who occur voltage level flip.

    Do you mean that must read 16 channel ports，and  then INT will return low？ Can you give me more detailed guidance？

    Thanks again.

  • +1 in reply to ling xinjie
    TI__Mastermind 47328 points

    Hi Ling,

    The /INT will return HIGH through a pull-up resistor once the interrupt has been cleared. To clear the interrupt, you must read from the input port that caused the interrupt. For example, if P00 triggered an interrupt, a read of input port register 0 will clear the interrupt after an ACK bit has been received by the host controller. 

    Regards,

    Tyler