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TCA9548A: Request review of circuit configuration

MJ Jeon
Genius 5240 points
Part Number: TCA9548A
Other Parts Discussed in Thread: SN74LV4051A, TMUX1208

Hi, TI support team

I am trying to configure as below by connecting multiple TCA9548A to one TCA9548A.

Is this a possible configuration?

Is it possible to connect to different register addresses as shown in the picture above?

If you have a better idea, please recommend it.

Thanks.

Regards,

MJ

  • 0
    Guru 318700 points

    I guess you need to do this because all 64 sensors have the same address?

    The TCA9548A has 8 possible addresses, but your image shows 9 devices; this will not work. There is no other I²C 8:1 switch with a different address range, so you need to replace one TCA9548A with plain analog switches (e.g., 2× SN74LV4051A or 2× TMUX1208) and control them with separate GPIO outputs.

  • 0
    TI__Guru 52698 points

    Hi MJ,

    Clemens is correct here, the configuration that you have here will not work due to limited I2C addressing. TCA9548A has only 3 address pins A2/A1/A0 which gives 8 different and unique addresses. In your configuration, you will need a total of 9 different addresses and therefore need a device that has a different I2C address, or implement a device that does not use I2C to conduct switching. Clemens mentioned a few analog switch options such as the SN74LV4051A or TMUX1208. 

    Please let me know if you have any more questions.

    Regards,

    Tyler

  • 0
    Intellectual 265 points

    This almost sounds like a bus that should be using the newest I3C interface?

    later

    Jim Mrowca

  • 0 in reply to James Mrowca
    TI__Guru 52698 points

    Hi Jim,

    I am not as familiar with the I3C interface, but does I3C offer the ability to operate a bus with multiple hardware addresses? The problem that I am seeing here is that two of the TCA9548A devices will have the same I2C address which could cause bus contention issues if both devices are active on the bus. This configuration would work if we were to take one of the eight TCA9548A devices off. 

    Regards,

    Tyler

  • 0 in reply to Tyler Townsend
    Prodigy 80 points

    Hi Tyler, 

    As you mentioned above, TCA9548A gives 8 different addresses. 
    I wonder if one master TCA9548A could control the other 8 different TCA9548A by using the master TCA9548A control register.

    MCU ------------> TCA9548A(1ea) --------------------------------------------> TCA9548A(8ea) -----------------------------------------------> Sensors(same adress, 64ea) 

                (I2C)                                   (control register of TCA9548A)                               (control register of each TCA9548A)

    Please let me know whether it is possible or not

    Regards,

    JUN HYEOB LEE

  • 0 in reply to JUNHYEOB LEE
    Guru 318700 points

    Yes. As long as no more than one channel on the master switch is enabled at the same time, it is indeed possible to give the eight other switches the same address. The only restriction is that the master switch must have a different address. (For example, master 000, other switches 8× 111.)

  • 0 in reply to JUNHYEOB LEE
    TI__Guru 52698 points

    Hi Jun,

    Please see Clemens' comments. It is possible to work this configuration if only one TCA9548A device is accessed at one time. 

    Regards,

    Tyler