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INA229: SPI sharing of INA229 and other devices

jung hoo Lee
Prodigy 10 points
Part Number: INA229

I want to control INA229 and another device using one SPI.
(Of course, it is assumed that the basic settings (CPOL, CPHA, etc.) are the same.)
However, when MISO of INA229 and another device (here AD5270 of analog device) is shared, data of INA229 cannot be read.
My question here is:

1. Should INA229 preclude SPI sharing with other devices in principle?
2. If at least partially possible, what should be considered?

I will wait for your reply.
thank you

  • +1
    Guru 244370 points

    In order for the MISO signal to be shared, all slaves must disable their MISO pin when they are not selected.

    Section 7.5.1 of the INA229 datasheet confirms that it tri-states the output when /CS is high. As far as I can see, the AD5270 does the same. (But it requires a pull-up resistor on SDO.)

    Please show an oscilloscope trace of a failing read.

  • +1 in reply to Clemens Ladisch
    TI__Genius 17990 points

    Hello,

    Yes, the INA229 can work with other SPI devices. To add to what Clemens said for a compatibility check, the INA229 uses CPOL = 0 and CPHA = 1.  I am not sure about the AD5270, but it's possible that you just need the pull-up resistor that Clemens mentioned. 

    Regards,

    Mitch

  • 0 in reply to Clemens Ladisch
    Prodigy 10 points

    Sorry for the late reply.
    It was confirmed that normal operation was performed when a pull-up resistor was added. Additional problems are with the other device, so they are off of this topic.
    In summary, INA229 is working well.
    thank you

  • 0 in reply to Mitch M
    Prodigy 10 points

    Thanks for the definite answer.
    i resovled this issue with clemens help.

    thank you.