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TCA9539: TCA9539RTWR I2C timeout

gorden tsai
Prodigy 210 points
Part Number: TCA9539

Hi Sir:

  Does  TCA9539RTWR  offer I2C bus time out feature when a serial interface

transmission is interrupted ?

Thanks

Gorden

  • 0
    TI__Guru 62920 points
    Hi Gorden,

    The device does not have an automatic timeout, although if it is causing the I2C bus to be held up then it can be manually reset via the RESET pin.

    Regards,
    Max
  • 0
    TI__Guru 73181 points

    Hey Gordon,

    I have not heard of I2C standard defining a time out parameter. doing a ctl+f and searching time out in both SMbus and I2C standard, I was not able to locate anything about this.

    None of our devices have a time out feature because it was never defined in I2C spec.

    Thanks,
    -Bobby

    Edit: SMbus does define timeout (had to search timeout without a space) however our devices are defined using I2C standard.

  • 0 in reply to BOBBY
    Prodigy 210 points
    Hi guy:
    Same like as below function :
    1. The TI TLA202x offer a I2C timeout feature that can be used to recover communication when a serial interface
    transmission is interrupted. If the host initiates contact with the TLA202x but subsequently remains idle for 25 ms
    before completing a command, the TLA202x interface is reset. If the TLA202x interface resets because of a
    timeout condition, the host must abort the transaction and restart the communication again by issuing a new
    START condition.
    2.The Maxim MAX7311 16Bit I/O Expander have I2C Bus time out function also ,can reference it.
    3.I would like to know,Which of TI 2C general purpose I/O products which one of parts has support I2C time out
    except TCA9539.

    Thanks
    Gorden
  • 0 in reply to gorden tsai
    TI__Guru 73181 points

    Hey Gorden,

    "I would like to know,Which of TI 2C general purpose I/O products which one of parts has support I2C time out except TCA9539."

    None of our IO expanders have an I2C time out feature.

    May I ask what end equipment/application you are trying to design? This is the first request we've had for an I2C timeout for our IO expanders. This seems like a gap in our portfolio and I would like to understand in which end equipment this feature is necessary. Likely I can pass this on to our systems engineer who may in the future, specify a time out feature in our future IO expanders.

    Thanks,

    -Bobby

  • 0 in reply to BOBBY
    Prodigy 210 points
    HI Bobby:
    Thanks reply
    Our application is IR PTZ Speed Dome.
    My last question :If I2C Bus interface transmission is interrupted,Our MCU send STOP condition and then issue start condition which TCA9539
    can re-connect I2C BUS communication ?

    Thanks
    Gorden
  • 0 in reply to gorden tsai
    TI__Guru 73181 points

    Hey Gordon,

    "If I2C Bus interface transmission is interrupted,Our MCU send STOP condition and then issue start condition which TCA9539
    can re-connect I2C BUS communication ?"

    No, the TCA9539 will get stuck if you are in the middle of a transaction. You will need to send 9 clock pulses onto the SCL line before performing another I2C start condition.

    Thanks,

    -Bobby

  • 0 in reply to BOBBY
    Prodigy 210 points
    Hi Bobby:
    Yes ,This is good information to me


    Thanks
    Gorden