stasundr

From UC Berkeley, starting 1/20/2015  https://www.edx.org/course/electronic-interfaces-uc-berkeleyx-ee40lx#.VH8h7GeNrcs

The only thing that jumps out at me is that your LED is connected to the serial RX pin. I know you aren't using serial RX but I wonder if using it in this fashion is interfering with the serial routines.
 
Other than that, the RTCplus library is more RAM hungry than it should be. When I did it, I was aiming for small code size rather than small RAM usage.  The above shouldn't run out of RAM, but if it is only a snippet from a larger piece of code, then it is possible you are encountering RAM problems.
 
As for the suggestion above about crystal capacitors, the MSP430 has built-in crystal caps, which the RTCplus library enables when it enables the 32k crystal.  However, the library does activate the 12.5pF capacitors, which are the ones used by the crystal that ships with the Launchpad.  Check the specs for your crystal and if it requires different values, you can change it in RTCplus.cpp - change the XCAP value in line 45 - XCAP_1 for 6pF, XCAP_2 for 10pF.

There are some limitation in using the write function. Calin has listed them in the post 4.
Impossibility to change the size of the file is one of them.

PFatFS uses the 8.3 naming convention.That means, a longer name will be "truncated" to 8 characters. In the case of a file with a name as you used ("SD card test.txt"), PFatFS shows me it as "SDCARD~1.TXT".
Maybe an ideea will be to start keeping just the directory listing part from the test sketch, to see if you have communication and just the name is wrong, or you don't have communication at all.
/*-----------------------------------------------------------------------*/ /* Program Main                                                          */ /*-----------------------------------------------------------------------*/ void loop() {     Serial.println();     Serial.println("Open root directory.");     delay(100);         rc = FatFs.opendir(&dir, "");     if (rc) die(rc);     Serial.println();         Serial.println("Directory listing...");         delay(100);     for (; {         rc = FatFs.readdir(&dir, &fno);    /* Read a directory item */         if (rc || !fno.fname[0]) break;    /* Error or end of dir */         if (fno.fattrib & AM_DIR) {Serial.print("<dir>\t"); Serial.println(fno.fname);delay(100);}         else {Serial.print(fno.fsize);Serial.print("\t"); Serial.println(fno.fname);delay(100);}     }     if (rc) die(rc);         Serial.println();     Serial.print("Test completed.");     //for (; ; } PS I'm using a tivac board.