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TCA9534A: the sequence of register setting

Part Number: TCA9534A

Dear all,

I want to use this device as output and default output level as "L".

To achieve this usage, I think to set as following sequence.

>1, set register 1 to change default output value as "L"

>2, set register 3 to define the direction as output

Does this sequence have some problem?

Best regards,

  • Hello Takao-san,
    The default state of all the port pins are as inputs, which means it is floating and could be interpreted as either a HIGH or LOW depending on leakage currents. Once you program it then it can be set as a OUTPUT that is LOW. It will remain LOW until you change it or if a POR event happens. If this is going to control something, then you may want to place a weak pull down resistor to ensure that it stays low at all times.

    Your sequence is correct.

    Francis Houde