title: Appending data with FatFS in a uSD
body: <p>I am using a SAMG55 and the FatFS library included in the ASF, everything seems to work properly, but when I try to append data to a file periodically it only works the first time. I mean, if my file has a size of 100, the first time the microcontroller open the file it says that the size is 100, but then I write a line and close the file. Next time I open it without rebooting the microcontroller it says that the size is always 4, the line is longer that 4 bytes.</p>
  
  <p>This is the code I am using:</p>
  
  <pre><code>f_open(&amp;file_object, (char const *)test_file_name, FA_OPEN_ALWAYS | FA_WRITE );
  f_lseek(&amp;file_object, file_object.fsize);
  f_printf(&amp;file_object, " Some data line \r\n");
  f_close(&amp;file_object);
  </code></pre>
  
  <p>Do you have any idea about what is happening?</p>
  
  <p>Thank you</p>