程序掉电丢失原因

#include <msp430.h>

void SetVcoreUp (unsigned int level);

int main(void)
{
  volatile unsigned int i;

  WDTCTL = WDTPW+WDTHOLD;                   // Stop WDT
 
  P3SEL |= BIT5+BIT6;                       // P3.5-3.6 option select
  P3DIR |= BIT5+BIT6;                       // P3.5-3.6 outputs
  // Increase Vcore setting to level3 to support fsystem=25MHz
  // NOTE: Change core voltage one level at a time..
  SetVcoreUp (0x01);
  SetVcoreUp (0x02); 
  SetVcoreUp (0x03); 
 
  UCSCTL3 = SELREF_2;                       // Set DCO FLL reference = REFO
  UCSCTL4 |= SELA_2;                        // Set ACLK = REFO

  __bis_SR_register(SCG0);                  // Disable the FLL control loop
  UCSCTL0 = 0x0000;                         // Set lowest possible DCOx, MODx
  UCSCTL1 = DCORSEL_7;                      // Select DCO range 50MHz operation
  UCSCTL2 = FLLD_0 + 762;                   // Set DCO Multiplier for 25MHz
                                            // (N + 1) * FLLRef = Fdco
                                            // (762 + 1) * 32768 = 25MHz
                                            // Set FLL Div = fDCOCLK/2
  __bic_SR_register(SCG0);                  // Enable the FLL control loop

  // Worst-case settling time for the DCO when the DCO range bits have been
  // changed is n x 32 x 32 x f_MCLK / f_FLL_reference. See UCS chapter in 5xx
  // UG for optimization.
  // 32 x 32 x 25 MHz / 32,768 Hz ~ 780k MCLK cycles for DCO to settle
  __delay_cycles(782000);

  // Loop until XT1,XT2 & DCO stabilizes - In this case only DCO has to stabilize
  do
  {
    UCSCTL7 &= ~(XT2OFFG + XT1LFOFFG + DCOFFG);
                                            // Clear XT2,XT1,DCO fault flags
    SFRIFG1 &= ~OFIFG;                      // Clear fault flags
  }while (SFRIFG1&OFIFG);                   // Test oscillator fault flag
   
  while(1)
  {
  TBCCR0 = 1024;                           // PWM Period 
  TBCCTL5 = OUTMOD_7;                       // CCR5 reset/set
  TBCCR5 = 512;                              // CCR5 PWM duty cycle 
  TBCCTL6 = OUTMOD_7;                       // CCR6 reset/set
  TBCCR6 = 216;                               // CCR6 PWM duty cycle 
  TBCTL = TBSSEL_2+MC_1;                    // SMCLK, upmode
  }
}

void SetVcoreUp (unsigned int level)
{
  // Open PMM registers for write
  PMMCTL0_H = PMMPW_H;             
  // Set SVS/SVM high side new level
  SVSMHCTL = SVSHE + SVSHRVL0 * level + SVMHE + SVSMHRRL0 * level;
  // Set SVM low side to new level
  SVSMLCTL = SVSLE + SVMLE + SVSMLRRL0 * level;
  // Wait till SVM is settled
  while ((PMMIFG & SVSMLDLYIFG) == 0);
  // Clear already set flags
  PMMIFG &= ~(SVMLVLRIFG + SVMLIFG);
  // Set VCore to new level
  PMMCTL0_L = PMMCOREV0 * level;
  // Wait till new level reached
  if ((PMMIFG & SVMLIFG))
    while ((PMMIFG & SVMLVLRIFG) == 0);
  // Set SVS/SVM low side to new level
  SVSMLCTL = SVSLE + SVSLRVL0 * level + SVMLE + SVSMLRRL0 * level;
  // Lock PMM registers for write access
  PMMCTL0_H = 0x00;
}