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Original question:

PCA9544A: Multi-Master Repeated Start

PCA9544A: PCA9544A

user6262427
Prodigy 30 points
Part Number: PCA9544A
Other Parts Discussed in Thread: PCF8574A

Hi All,

One more question regarding I2C addressing.

PCA9544A has 3 address select pins. Usually it is enough to tie them up or down for infinity.

But this time I need to change address on the fly.

Can I change address when bus is idle ?

For example :

I would like to connect PCA9544A to same bus with PCF8574A and use I/O outputs (PCF8574A) to control PCA9544A adress inputs.

Can I do that this way ?

best regards

AGi

  • 0
    TI__Guru 64870 points

    Hi AGi,

    Yes, you should be able to do this with devices that don't latch their I2C addresses upon power up. As far as I know, our I2C responder devices do not latch the I2C address. This concept your talking about is discussed in this app note: 

    Dynamic addressing

    -Bobby

  • 0 in reply to BOBBY
    Prodigy 30 points

    Hi Bobby,

    Yes, I know this App note.

    I still do not see info regarding address latching or not latching in PCA9544A. If something is not written , may change without notice.

    Best regards

    AGi

  • 0 in reply to user6262427
    TI__Guru 64870 points

    Hi AGi,

    The PCA9544A doesn't latch it's address so you can use it in the way you were describing.

    -Bobby