topic PCA9502 read back gpio using spi not working in Other NXP Products

PCA9502 read back gpio using spi not working

subrahmanyapere — Fri, 04 May 2018 21:12:56 GMT

i am trying to do a read back of gpio lines using spi and it is not working.I have attached the spi commands i am sending.Please let me know what i am doing wrong .

Re: PCA9502 read back gpio using spi not working

reyes — Mon, 07 May 2018 21:04:10 GMT

Hi,

The usual steps on the master side for writing are:

* Configure desired speed within slave spec

* Assert SS/CS

* Send write command

* Start sending data/Ignore incoming data

* Stop by de-asserting SS/CS

The usual steps on the master side for reading are:

* Configure desired speed within slave spec

* Assert SS/CS

* Send read command

* Send dummy data/received data

* Stop by de-asserting SS/CS

In the image you sent I cannot see the SS/CS configuration unless is the “SPI EN” signal in which case is not doing what it supposed to do.

Regards,

Jose

NXP Semiconductor

Re: PCA9502 read back gpio using spi not working

subrahmanyapere — Tue, 08 May 2018 17:56:11 GMT

i still have the same problem.you can see my spi enable line goes low during the transaction .but my miso line returns ff.

I write to reg A abd read on reg B.

Re: PCA9502 read back gpio using spi not working

subrahmanyapere — Wed, 16 May 2018 19:44:35 GMT

I am still having the same issue can you please help me fix this .I just want to read the gpio ports and these are the spi transactions i send