topic Re: PCA9502 SPI not working in Other NXP Products

PCA9502 SPI not working

henry_wusa — Thu, 23 Jun 2022 03:20:19 GMT

Hello,

I am using PCA9502 and want to use its SPI interface to read 8 GPIO pins.

First, I hardware reset PCA9502 and configure it by writing the values into internal registers.

Register	Registers Address	Value
IODir	0x0A	0x00
IOIntEna	0x0C	0x00
IOControl	0x0E	0x08

Using the SPI interface, the actual MOSI address needs to be shifted 3 digits and they will be like:

Register	Address	Value
IODir	0x50	0x00
IOIntEna	0x60	0x00
IOControl	0x70	0x08

Then I read the GPIO pins by reading the internal register 0x0B and the actual MOSI address will be 0xD8. However, after I send 0xD8 into PCA9502, the logic analyzer shows that PCA9502 output is always High no matter what the GIPO pins are (as below).

Re: PCA9502 SPI not working

guoweisun — Thu, 23 Jun 2022 06:09:30 GMT

Except this internal registers write/read abnormal, can other registers write/read normally?

Re: PCA9502 SPI not working

henry_wusa — Thu, 23 Jun 2022 08:16:58 GMT

Hi,

There are only five registers in PCA9502:

I write "0x00" into these registers, and always read out with the same value "0xFF".

Additionally, I think my problem is similar to this.