CCS/MSP430G2553: Setting the DCO to lower frequency during ideal time

#include "msp430g2553.h"
#include <driverlib.h>
#ifndef TIMER0_A1_VECTOR
#define TIMER0_A1_VECTOR TIMERA1_VECTOR
#define TIMER0_A0_VECTOR TIMERA0_VECTOR
#endif
#include <SPI.h>
#include <pfatfs.h>
#include <pffconf.h>
#include "SPI.h"
#include "pfatfs.h"
#define cs_pin      8             // chip select pin 
#define read_buffer 128             // size (in bytes) of read buffer 
unsigned short int bw, br;
char buffer[read_buffer];
int rc;
DIR dir;                /* Directory object */
FILINFO fno;            /* File information object */
uint32_t sensor1;
uint32_t sensor2;
uint32_t sensor3;
uint32_t sensor4;
uint8_t StringLength = 0;
char buf[50];
uint32_t counter = 0;
uint32_t AccStringLength = 0;
unsigned long time;
int c=1;
uint32_t t1 = 0;
uint32_t t2 = 0;
uint32_t t3 = 0;
uint32_t t4 = 0;

void setup()
{
 analogReference(INTERNAL2V5);
    pinMode(9, OUTPUT);
    pinMode(10,OUTPUT);
   FatFs.begin(cs_pin);
   digitalWrite(10,HIGH);
   delay(200);
   digitalWrite(10,LOW);
   delay(200);
}

void loop()
{
  digitalWrite(9,HIGH);
  sensor1 = analogRead(2);
  delay(5);
  t1 = sensor1;
  sensor2 = analogRead(3);
  delay(5);
  t2 = sensor2;
  sensor3 = analogRead(5);
  delay(5);
  t3 = sensor3;
  sensor4 = analogRead(6);
  delay(5);
  t4 = sensor4;

digitalWrite(9,LOW);

   rc = FatFs.open("LOG.TXT");
   delay(5);
   bw=0;
   sprintf(buf,"%lu Output is %lu,%lu,%lu,%lu\r\n",counter,t1,t2,t3,t4);
   counter++;
   StringLength =  strlen(buf);
   rc = FatFs.lseek(  AccStringLength );
   AccStringLength =  AccStringLength + 1024;
   rc = FatFs.write(buf,StringLength,&bw);
   rc = FatFs.write(0,0,&bw);   //Finalize write
   rc = FatFs.close();         //Close file

   BCSCTL1 = 0x0; // Set range
   DCOCTL = 0x0;
   delay(1000);
   BCSCTL1 = 0xA0; // Set range
   DCOCTL = 0x8F;
}