Hi,

You are right. I have 4 PCA8574T I/o Expander chip.


On Sat, Sep 6, 2014 at 1:55 AM, <[email protected]> wrote:

> So it appears you should expect to see a device between 0x20 through 0x27
> from the datasheets.   The device address is 0*0100000* when not shifted
> for the R/W bit.   That corresponds to 0x20 as the base chip address and
> the A1,A2, and A3 pins can set up to 7 other address for the final three
> bits.   I2C can be really confusing in how the addresses are specified in
> various datasheets.  Linux reports the 7 bit address of devices it finds in
> hexadecimal.
>
>
> I see your output shows devices at 0x20, 0x22, 0x26, and 0x28.   That
> appears to be the correct* hecxidecimal*, *7-bit,* addresses for the
> chips?  Do you have 4 chips wired up?
>
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