RTOS/CC2640R2F: AFE4300 interfacing with CC2640R2F - SPI Issue

Tool/software: TI-RTOS

Hi,

I am interfacing AFE4300 with CC2640R2F. I have assigned SPI pins in board file and setup SPI communication. SPI_Init and SPI_OPEN works fine without any failure.

But when I write to AFE4300 register and read back it, it always returns me 0xFF. I have checked below signals in oscilloscope

1. I am getting 1 MHz clock for AFE4300 

2. Chip Select pin works 

3. SPI clock works fine as well

Then what could be issue? 

Appreciate your support. 

Thanks.