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PCA9543A issue

and
Prodigy 205 points
Other Parts Discussed in Thread: PCA9543A, PCA9534A

I am finding trouble using the PCA9543A “TWO-CHANNEL I2C-BUS SWITCH WITH INTERRUPT LOGIC AND RESET”. I am able to communicate with the chip and select the channel by writing to its control register. But after that it does not allow the data to pass through to the selected channel.

 

Once I write to the chip & select a channel should I get  a connectivity between the I2C lines and the selected channel?

We are connecting the master on the I2C lines and the slave on the channels. I have attached the snapshot of my data transfer.  Please let us know how this works.

 

Thanks,

Nihar

  • 0
    TI__Guru 71526 points

    AD,

      No attachment with the initial posting, please send direct to me, along with the schematic. 

    What is the i2C address they are using?  

     Any other i2C devices on this bus? 

    How are they handling RESET?  Also note there is a POR Errata on the PF page: http://www.ti.com/litv/pdf/scpz010 , minimum 100ms POR, < 10ms risetime.

    -Leonard 

       

     

  • 0
    TI__Guru 71526 points

    Need to see a schematic, see how the address bits as well as the IO pins are connected. 

    Also, a timing diagram that can show enough detail to relate to the parameters on page 10 of the datasheet.  Timing capture should show both an entire command sequence, plus an expanded capture with the edge timing.

    Thank you!

    Leonard Ellis

    ACAT Dallas 

    . . .

  • 0 in reply to LeonardEllis
    Prodigy 20 points


    Hi Leonard Ellis,

    The schematic we are using is the same as mentioned on page 14 of this datasheet:http://www.ti.com/lit/ds/scps169/scps169.pdf

    Also I have attached the screen shot of the data transfer as observed on the logic analyzer. The SCL frequency I am using is 51 khz approx. Please let me know what you think.

    Thanks,

    Nihar

  • 0 in reply to Nihar Joshi1
    TI__Intellectual 2020 points

    Hi Nihar,

    What voltages you are using for SDA/SCL, VCC and SD0/SC0 and what pull-ups are you using for the I2C buses?

    Also, can you attempt to read back from the PCA9534A and let me know what the response is?

    Regards,
    Chris Kraft 

  • 0 in reply to Chris Kraft
    Prodigy 20 points

    Hi Chris Kraft,

    We have resolved the issue. The problem was from our side. However, still there is one thing that I don't understand. After I switch to a particular channel by writing to a control register and then read back the control register to verify the data written, the first I2C dta transaction always fails but it all the transactions henceforth are successful.

    can you attempt to read back from the PCA9534A and let me know what the response is?

    When I read back from the PCA94543A I get 0x01 if I have selected channel 0 and 0x10 if its channel 1.

    Regards,

    Nihar Joshi