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TCA9535: Interruptions do not work properly

Part Number: TCA9535

Hello all,

    Now we have a trial production of a machine, the button did not interrupt to come;The button did not respond for a period of time under 1.8v voltage.The IIC communication is normal, and the interrupt pin is always low (no button is pressed) when there is a problem.The host does not initiate I2C communication when it is interrupted.Use 1.8v on one end of the multimeter current range, and connect the interrupt pin on the other end. After an instantaneous current of more than 10 milliamps, the circuit will return to normal, and the interrupt pin level will be higher

  • Hi Wade,

    Is the problem that the INT pin is always low and so button pushes are not detected? If so, have you tried reading the input port register? This should clear the interrupt until the next input state change occurs. If you have tried this and the interrupt is still low, can you verify that the input port register value matches the values observed (via multimeter) at each pin during the read?

    If you never see a high level on INT then it would be good to double check that R25 is properly connected, since the output uses an open drain driver.

    Max
  • Hey Wade,

    1) When this device device is turned on, what is the INT pin (high or low)?
    2) When does the INT pin latch low? (when you press a button or randomly)?
    3) After the pin latches low, does a read fix the issue?
    4) Looking at your schematic, I see that A2 looks like it is floating, do you actually have to tied to GND or Vcc somewhere else or is it really floating?
    5) Can you show us with a scope shot of what Vcc looks like when you turn on and off the device?
    6) Do you know how much current is going into Vcc? (you can use R21 to look at the supply current with a multimeter)

    Thanks,
    -Bobby
  • Hi Wade,

    Were you able to resolve this issue? If not, could you please help us better understand things by addressing some of the questions above?

    Thanks,
    Max