PCA9570 I2C Write/Read question

Jay_Zhu — Fri, 05 Mar 2021 07:41:57 GMT

Hi Team

I am confused about PCA9570 I2C write read, about the data1.

As the Figure shown, Host need address PCA9570 firstly, and then send data1,data2.

So that's a question here, what the data1 make sense?

Is data1 Pin Mask?

I tried to enable P0 and I send 0x48 + 0xff + 0x01. P0 is enabled.

But 0x48 + 0x01. Can not enable.

And 0x48 + 0x01 + 0x01. enabled also. And I see P0 has a shake , P1 too.

So I don't know what data1 need to be?

Then the read reg, I will send 0x49 + data1?

data1 is port pin? like 0x01 means P0?

And what the data from PCA9570 means? All of pins' status? or just the data1 reponse pin I sent .

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