AFE4960EVM: Interfacing with Arduino UNO as the MCU: FIFO wont read out

Tool/software:

Hi,

I am trying to interface the AFE4960 chip on the EVM with an Arduino UNO board as the MCU using SPI communication as specified in the datasheet. However, I am unable to get any output from the FIFO.

I have connected to the AFE1 pins as shown in the attached picture (the breadboard only has resistors and a transistor for level shifting from 5V to 1.8V required by the AFE chip).

Here is what my Arduino code does:

1. Pulls the SEN signal high (idle state for SPI communication)
2. Adjusts the SPI settings (clock frequency, MSB first, rising edge reading, etc.)
3. Writes to registers (exactly as done in the provided EVM code "11_1ECG_1.py")
4. Reads the FIFO buffer by sending FFh to the AFE chip

As seen in the attached screenshot, nothing is read on return for FF.

I can write to and read from all registers, except for registers 28h, 38h, and 6Dh, which return different values than what I sent. For register 00h (the one with the FIFO enabled bit), I also only read back 0 even though I write 40h and 41h respectively to write and read.

I have followed all the instructions in the user guide and datasheet. Could I please get some support on this issue?

Thank you!
Miguel

SPI_AFE4960.zip