PCA9701 PCA9702 SPI explanation and example

[travist]

Hello,

I am looking at using the PCA9701 in some of my products. I realize the SPI interface appears to be simple, but the explanation of use seems a little vague on the datasheet and I would appreciate a little more detail on how to use this product. 

I would be using it with 12v pull ups, then run through 100k resistors into the inputs. The outputs would be pulled low for "active" states. 

Thank you for the time.

[travist · Accepted solution]

It looks like I made the stereotypical issue of searching for a hardware issue when it happened to be a design issue. I had other CS lines active causing other SPI devices to corrupt the response of the PCA9701. 

The chip is actual as simple as it seems. 
Polarity = 0

Phase = 1

You then send 2 dummy bytes to receive 2 bytes showing the IO states. 

[travist]

I am having some trouble making this chip work and some clarity of Phase, Polarity, what should be sent, and what is expected to be returned will help remove variables while troubleshooting this. 

Thanks