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TCA9548A: is it possible to enable multiple channels at the same time?

Aki Li
Genius 9735 points
Part Number: TCA9548A

Customer is asking whether it is possible to enable multiple channels at the same time. From the datasheet, it seems that it can work with enabling multiple channels for the control register . However, i am not quite clear about why we need this, since the master send or receive data from a slave at one time. Could you help explain it? Thank you.

  • 0
    TI__Guru 72521 points

    Hey Aki,

    "Customer is asking whether it is possible to enable multiple channels at the same time."

    Yes, this device allows multiple channels to be enabled at the same time.

    "However, i am not quite clear about why we need this, since the master send or receive data from a slave at one time. Could you help explain it?"

    You make a good point here.

    One reason why a customer may choose to use a I2C switch is for the level translation properties, not a I2C address conflict. In this case, you could enable all the channels to talk to slaves on the other side without having to talk to the I2C switch before each transaction.

     

    -Bobby

  • 0 in reply to BOBBY
    TI__Genius 9735 points

    Bobby,

    Thank you. I have another question for the A0, A1, and A2 pins. In normal applications, how should we deal with these 3 pins? Do we need to configure these 3 pins to decide which slave access?  However, the Write to Register already includes the slave address information. 

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  • 0 in reply to Aki Li
    TI__Guru 72521 points

    Hey Aki,

    The address pins are for assigning the TCA9548A its address. TCA9548A is a slave device so its address should be unique on the bus. You do NOT typically change the address pins (a2, a1, a0) after the device has been powered up.

    Typical I2C transaction would be:

    (1) send TCA9548A address with write bit

    (2) send 8 bits for which channel you want to enable

    (3) send stop bit

    (4) talk to slave on other side of device now that you enabled the channel from step 2

    Does this make sense?

    -Bobby

  • 0 in reply to BOBBY
    TI__Genius 9735 points

    Bobby,

    Highly appreciated!