• State TI Thinks Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 33 subscribers
  • Views 442 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TCA9555: 10-bit addressing.

Peter Morrow
Prodigy 50 points
Part Number: TCA9555

Hi Folks,

I've got a few of these IO expanders in a system where there are some other I2C slaves with 10-bit addresses and would like to run the bus in 10-bit mode.  I've briefly tested the expanders and it seems that they do not ACK (ignore the upper address bits) back when my bus is running in 10-bit mode, they do however work perfectly in 7-bit mode.

Question is, should these io expanders work ok if they receive a 10-bit address (i.e. just ignore everything but the 7bits and RW bit).

Thanks,

Peter.

  • 0
    TI__Mastermind 49040 points
    Hey Peter,

    This should not be a problem but you need to be sure the addresses (the 10 bit addresses) are not the same as the 7 bit addresses when you send the two "addressing" bytes (used for 10 bit addressing) otherwise there will be contention issues. The 7 bit I/O Expander's state machine will basically ignore the 10bit addresses unless it sees it's own address.

    Keep in mind, if you run into addressing issues, you can use an I2C switch to resolve it as well.

    Thanks,
    -Bobby
  • 0 in reply to BOBBY
    Prodigy 50 points
    Hi Bobby,

    Thanks for the quick reply! OK, I'll double check nothing is colliding and will get back to you.

    Thanks,
    Peter.