INA229: SPI sharing of INA229 and other devices

jung hoo Lee

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

over 1 year ago

+1 Clemens Ladisch over 1 year ago

Guru 283330 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 Mitch M over 1 year ago in reply to Clemens Ladisch

TI__Mastermind 22135 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 jung hoo Lee over 1 year ago in reply to Clemens Ladisch

Prodigy 30 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 jung hoo Lee over 1 year ago in reply to Mitch M

Prodigy 30 points

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

thank you.

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INA229: SPI sharing of INA229 and other devices