Can BF514 support SDXC? And what speed class of SDXC is it?
In cace of SDXC, BF514 needs File System of exFAT.
Do you have the exFAT?
Since the controller doesn't support the SDXC, you will have to implement many things in software, but for that you have go through SD spec and see what are the features missing in the controller which need to be addressed in software. I haven't worked on SDXC so don't have much expertise here.