[FreeRTOS+FAT Standard API Reference]
size_t ff_fwrite( const void *pvBuffer, size_t xSize, size_t xItems, FF_FILE * pxStream );
Writes data to 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 written.
A pointer to the source of the data to be written to the
The size in bytes of each item being written to the file.
The number of items to write to the file. The size of
each item is set by the xSize parameter.
A pointer to the file to which the data is being written.
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 written to the file is returned. The number of items written to the file will only equal the number of bytes written to 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_fwrite() is used.