[FreeRTOS+FAT Standard API Reference]
size_t ff_fread( void *pvBuffer, size_t xSize, size_t xItems, FF_FILE * pxStream );
Reads data from the current read/write position within an open file in the embedded FAT file system. The read/write position is incremented by the number of bytes read.
A pointer to the buffer into which data read from the
file will be placed. The buffer must be at least large
enough to hold the number of bytes being read.
The size in bytes of each item being read from the file.
The number of items to read from the file. The size of
each item is set by the xSize parameter.
A pointer to the file from which the data is being read.
This is the same pointer that was returned from the call
to ff_fopen() used to originally open the file.
The number of items actually read from the file is returned. The number of items read from the file will only equal the number of items read from the file when the item size is 1. The size of each item is set by the xSize parameter.
The example provided on the ff_fopen() documentation page shows how ff_fread() is used.