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TCA9554A: I2C interrupted 8 extended I/Os. Can it be used as a GPIO? Can I2C's extended I/O output a fixed frequency always, that is, DCLK?

user5707026
Genius 3145 points
Part Number: TCA9554A
Other Parts Discussed in Thread: TCA9534, TCA6408A, TCA9538

Hi Engineer,

1. I2C interrupted 8 extended I/Os. Can it be used as a GPIO?
2. Can I2C's extended I/O output a fixed frequency always, that is, DCLK?
3. If the I/O port of the MCU is not enough, is there a good solution recommended? Is the type of serial interface to parallel interface. The whole cost is very small.

Thanks 

BRs

Elsa Duan

  • 0
    TI__Guru 62920 points
    Hi Elsa,

    I don't understand what you mean by your first question. What would be the difference between an extended IO and a GPIO?

    In general this device is used as a way of increasing the number of GPIOs in a system when there are too few available on an MCU. The IO expander provides 8 additional GPIOs and their states are communicated to the MCU using the I2C interface. This is a 2-wire serial interface.

    It would be possible to manually toggle any output of the IO expander high and low to create a clock waveform, but it could not be done automatically. You would need to configure the signal high, then low, then high, etc. This would mean that the effective clock frequency would need to be much less than the I2C data rate.

    Regards,
    Max
  • 0 in reply to Miguel Robertson
    Genius 3145 points
    Hi Max,
    Thanks for your great advice.
    About realizing, If you have any part number recommend to me?
    Thanks again.

    Elsa
  • 0 in reply to user5707026
    TI__Guru 72401 points
    Hey Elsa,

    Can you provide more information on what is important to you so we can suggest a device?

    Possible careabouts:
    1) size?
    2) price?
    3) Number of I/Os needed?
    4) Interrupt feature?
    5) Reset feature?
    6) Separate Vccs for ports and I2C logic?

    Thanks,
    -Bobby
  • 0 in reply to BOBBY
    Genius 3145 points
    Hi Bobby,
    1 no size limit;
    2 the more low price more better;
    3 8 I/O;
    4 I2C interrupt feature;
    5 Level reset;
    6 No, use the Vcc of MCU;

    Thanks
  • 0 in reply to user5707026
    TI__Guru 72401 points

    Hey Elsa,

    In terms of cost, TCA9534 seems to be the lowest on our 1k pricing (note no reset pin).

    If you do want a reset pin and INT feature then TCA6408A would be the first choice and TCA9538 would be pick number 2.

    Thanks,

    -Bobby

  • 0 in reply to BOBBY
    Genius 3145 points
    ok
    Clear.
    Thanks