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Original question:

TCA9554: TI TCA9554 drop-in of NXP PCA9554

TCA9554: Writing register 0x01 before 0x03

Luc
Prodigy 30 points

Part Number: TCA9554

Hi,

To be clear.
As per default all I/O pins are configured as inputs.
When I would write to 0x01 (configuring the logic levels for outputs) and only after that, writing to 0x03 which of the ports should be configured as outputs or inputs, the status is directly adapted for the outputs.

So there is no need to write again to 0x01 or a delayed response when to the defenition of the output, correct?

  • +1
    TI__Guru 61838 points

    Hi Luc,

    Luc said:
    So there is no need to write again to 0x01 or a delayed response when to the defenition of the output, correct?

    Correct. 

    Set the logic of the pins configured to output by writing to 0x01. 

    Then set the direction of the pins from INPUT --> OUTPUT through configuration register 0x03. 

    Once 0x03 register is set, the logic selected in register 0x01 will immediately apply to the pins configured as output. 

    Regards,

    Tyler