Dwm1001 read from SPI

Hello, I’m coding a custom sender/receiver module.
I don’t use the firmware, but I wrote a code starting from the simple examples.
Let me define the sender as TX and the receiver as RX.
TX just sends a message and RX just receives the sent message.
This works properly.

Now, TX is connected to a Raspberry over the SPI using the 26 pins header.
My goal now is to send a message which is written by a script inside the Raspberry.
I’m struggling with this aspect.
I don’t know how to read from SPI from the antenna main program.