SPI NOR FLASH with FatFS in nRF52832

Question

Hi everyone! 
 I am working on a project where I have to store files inside a FLASH coming from a GATT server , and be able to manage them through FAT in a GATT client . The part of sending and receiving data through BLE works correctly. 
 I am using the following Software/Hardware tools: 
 
 nRF5_SDK_17.1.0 
 nRF52832 
 SPI NOR FLASH 32Mbit (4MB)- AT25DF041B 
 Segger V5.70 
 FatFS - http://elm-chan.org/fsw/ff/doc/getfree.html 
 Windows 10 64 bits 
 
 Looking through the examples provided by the SDK, I find the following example: 
 ...
RF5_SDK_17.1.0\examples\peripheral\fatfs 
 This example incorporates the FAT but with an SD card. For my project I need to format the FAT on my SERIAL NOR FLASH and mount the volume. 
 Reading ChaN's FatFS documentation I need to make my own low level disk I/O layer, and make the connection to the FatFS module. Having said the above, I have already done my low-level disk I/O layer and the connection with the FatFS module but I am not getting the expected results. Before I continue, I'd like to check a few things in my project settings to make sure it's set up correctly. 
 AT25DF041B can be erased in sizes of 256B, 4KB, 32KB and 64KB. Reviewing the ffconfig.h file I find that: 
 #define FF_MIN_SS 4096
#define FF_MAX_SS 4096
/* This set of options configures the range of sector size to be supported. (512,
/ 1024, 2048 or 4096) Always set both 512 for most systems, generic memory card and
/ harddisk. But a larger value may be required for on-board flash memory and some
/ type of optical media. When FF_MAX_SS is larger than FF_MIN_SS, FatFs is configured
/ for variable sector size mode and disk_ioctl() function needs to implement
/ GET_SECTOR_SIZE command. */ 
 1 .- Set the sector size to 4096 for FAT because it fits the erase sector in FLASH which is also 4096, is this setting correct? 
 In my code I mount the volume with f_mount , and in case of returning FR_NO_FILESYSTEM I proceed to format the FLASH WITH f_mkfs . Everything is going perfect up to that point, but when I get the free sectors with f_getfree or I want to write a file larger than 230KB the problems start.This means that the FLASH is not being formatted or mounted correctly. 
 2.- What I would expect from f_getfree would be the free clusters on the volume, in my case there is one sector per cluster (4096*1). So I would expect to get (1024 clusters - VBR) * 4096 bytes and this would result in a value close to 4,194,304 = 4 MB, is this true? FATFS *fs;
 DWORD fre_clust, fre_sect, tot_sect;


 /* Get volume information and free clusters of drive 1 */
 res = f_getfree("1:", &fre_clust, &fs);
 if (res) die(res);

 /* Get total sectors and free sectors */
 tot_sect = (fs->n_fatent - 2) * fs->csize;
 fre_sect = fre_clust * fs->csize;

 /* Print the free space (assuming 512 bytes/sector) */
 printf("%10lu KiB total drive space.
%10lu KiB available.
", tot_sect / 2, fre_sect / 2); 
 If you have sample code that you can provide with SPI NOR FLASH and FATFS using nRF52832 I would greatly appreciate it.