MSP430 Real time clock (RTC_B) doesn't work. Cannot write date/time registers

Question

I'm trying to set date/time registers using the RTC_B module of MSP430F5338 microcontroller. I'm doing it like this:

RTCCTL0 = 0;
RTCCTL1 |= RTCHOLD +RTCBCD;
RTCHOUR = 0x14;
RTCCTL1  &= ~RTCHOLD;

It doesn't work, and simply ignore the assignements. I cannot understand why. The only strange thing I've noticed is the RTCOFIFG flag set.

Any idea?

Addendum

This is how I set up clock sources:

void clk_init(){
  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_1 | ((f_SMCLK/f_ACLK) -1);                   // 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


  // 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

}

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;
}

Answer 1

I've SOLVED adding this before clock setup:

 while (BAKCTL & LOCKBAK) BAKCTL &= ~LOCKBAK;

Basically this is due to the fact that msp430f5338 has the battery backup system, so you'll need this code before you set XT1 drive ACLK.

Hope this helps.

Answer 2

Having just had a browse through the datasheet - two things:

1. By setting the RTCBCD flag in RTCCTL1, you're saying you want to use binary-coded decimal, so setting RTCHOUR as 0x0A is nonsense. To write proper BCD for, say, 14:47 (2:47pm), you write the hours as 0x14 and 0x47 as the minutes, i.e., write as you see.

2. Ensure you're not in low power mode 5 (LPM5) - configuration settings are not retained.

Addendum:

Also, the RTCOFIFG flags says you had a fault with your oscillator, so confirm your circuitry too.