MOD54415 SPI problems

[jediengineer]

Hi all,

I'm using a MCP23S08 GPIO expander with my proto board, and I'm having trouble with it. It's not responding. And I'm wondering if it's because something is wrong with the SPI channel. I attached my code and a snapshot from my logic probe... the SCLK signal looks a bit weird. I've reviewed my schematic. I can't find any trace shorts, or anything wrong with the circuit so the only conclusion that I have is that it must be due to the clock signals.

Note that the DIN and DOUT lines are labelled backwards.

I do have an ADC that uses SPI3, and is working perfectly. So I'm fairly certain that my SPI channel is set up correctly.


Can anyone verify that this should or shouldn't look like this? Thanks!

Tony