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Question about TCA9544A I2C

MohammedAl-Amin
Intellectual 540 points
Other Parts Discussed in Thread: TCA9544A

Hello,

I have been looking at the TCA9544A, We have four slave devices we plan to connect, Three of the devices are have Interrupt pins but our fourth device which is an OLED Display does not have an interrupt. Would the OLED display still work with TCA9544A and would we tie the fourth I2C slave interrupt to ground?

Also my other question would be three of my slave devices require to be tied up to 3.6V and one slave device require 5V for tie up.

My Question is can I connect all these slaves to my master which requires a pull up of 1.8V using the TCA9544A?

On the datasheet description (first page) is says:

'This allows the use of different bus voltages on each pair, so that 1.8-V, 2.5-V, or 3.3-V parts can communicate with 5-V parts without any additional protection'

Which confused me.

Best regards Mohammed Al-Amin

  • 0
    TI__Genius 17225 points
    Hello Mohamed,
    Can you send me a schematic or I2C tree that included all the devices, addresses and Vcc voltages? That will help me see if you are setting all the supplies correctly.
    Any unused /INT input pins need to be tied to Vcc, NOT ground. I don't see why you can't do what I think you are trying to do, just show me your schematic just to make sure.
    -Francis Houde
  • 0 in reply to fhoude
    Intellectual 540 points

    As it may not be seen clearly but SC3, SD3 and INT3 are not being used:

    SC3 and SD3 are connected to Ground

    INT3 is connected to 1.8V.

    As for the Master SDA, SCL and INT they are connected to MCU with 10k pull ups to 1.8V (using R6, R4 and R5)

    As for the Slaves:

    Slave 0

    SD0 and SC0 are pulled up to 3.3V with 10k Pull-ups

    INT0 - as my slave doesn't use it I have pulled it up to 1.8V (Should I pull it up to the same voltage at SD0 and SC0  of 3.3V?)


    Slave 1

    SD1,SC1 and INT1 are pulled up to 1.8V using 10k resistors

    Slave 2
    SD2,SC2 and INT2 are pulled up to 1.8V using 10k resistors

    I hope this helps to understand they are port on the image below I explained above how they are connected from the other end.

    If you need more information please let me know
    Also to let you know there are two voltages being used 1.8V which is used by everything except SD0 and SC0 which is running on 3.3V

    Best regards

    Mohammed