MSP430F5418A能否动态写RTC寄存器？谢谢

Lanshun Nie

Prodigy 20 points

Other Parts Discussed in Thread: MSP430F5418A

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我们在项目中拟使用MSP430F5418A的RTC功能，日历模式，想实现的功能是当收到网络时间同步消息后，通过写RTC的寄存器

直接修改年、月、日、时、分、秒等信息。写寄存器函数的代码如下所示。该代码能够修改RTCYEAR等寄存器，但是似乎会导致

一些奇怪的现象，如RTC走时过程中RTCMIN突然不正常跳变等。请教TI的工程师，日历模式下RTCYEAR等寄存器和RTCAMIN寄存器

能够在运行时被动态地修改？如果可以，如何安全地修改这些寄存器？谢谢！

void write_calendar(calendar_time caltime)
{
   for(;!(RTCCTL01&RTCRDY););
RTCYEAR = caltime.year ;        // Year
RTCMON = caltime.mon ;        // Month
RTCDAY = caltime.day ;        // Day
RTCDOW = caltime.day_of_week ; // Day of week
RTCHOUR = caltime.hour ;        // Hour
RTCMIN = caltime.min ;        // Minute
RTCSEC = caltime.sec ;        // Seconds
}

9 年多前

0 Ling Zhu2 9 年多前

TI__Genius 17346 points

建议看一下用户手册：

22.2.2.3 Reading or Writing Real-Time Clock Registers in Calendar Mode Because the system clock may be asynchronous to the RTC_A clock source, special care must be taken when accessing the real-time clock registers.

In calendar mode, the real-time clock registers are updated once per second. To prevent reading any realtime clock register at the time of an update, which could result in an invalid time being read, a keepout window is provided. The keepout window is centered approximately -128/32768 s around the update transition. The read-only RTCRDY bit is reset during the keepout window period and set outside the keepout the window period. Any read of the clock registers while RTCRDY is reset is considered to be potentially invalid, and the time read should be ignored. An easy way to safely read the real-time clock registers is to use the RTCRDYIFG interrupt flag. Setting RTCRDYIE enables the RTCRDYIFG interrupt. Once enabled, an interrupt is generated based on the rising edge of the RTCRDY bit, causing the RTCRDYIFG to be set. At this point, the application has nearly a complete second to safely read any or all of the real-time clock registers. This synchronization process prevents reading the time value during transition. The RTCRDYIFG flag is reset automatically when the interrupt is serviced, or can be reset with software. In counter mode, the RTCRDY bit remains reset. RTCRDYIE is a don't care and RTCRDYIFG remains reset.

NOTE: Reading or writing real-time clock registers When the counter clock is asynchronous to the CPU clock, any read from any RTCSEC, RTCMIN, RTCHOUR, RTCDOW, RTCDAY, RTCMON, RTCYEARL, or RTCYEARH register while the RTCRDY is reset may result in invalid data being read. To safely read the counting registers, either polling of the RTCRDY bit or the synchronization procedure previously described can be used. Alternatively, the counter register can be read multiple times while operating, and a majority vote taken in software to determine the correct reading. Reading the RT0PS and RT1PS can only be handled by reading the registers multiple times and a majority vote taken in software to determine the correct reading or by halting the counters. Any write to any counting register takes effect immediately. However, the clock is stopped during the write. In addition, RT0PS and RT1PS registers are reset. This could result in losing up to 1 s during a write. Writing of data outside the legal ranges or invalid time stamp combinations results in unpredictable behavior.

0 Lanshun Nie 9 年多前回复 Ling Zhu2

Prodigy 20 points

谢谢您的回答。

用户手册这一部分我们仔细研究过了，但还是没把握，所以才上来提问。

可否给一个正确写RTC寄存器的例程？谢谢！

0 Ling Zhu2 9 年多前回复 Lanshun Nie

TI__Genius 17346 points

写的时候应该把RTC hold 住吧

#include <msp430.h>

int main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                 // Stop Watchdog Timer
  P1DIR |= BIT0;                            // Set P1.0 as output

  // Initialize LFXT1
  P7SEL |= 0x03;                            // Select XT1
  UCSCTL6 &= ~(XT1OFF);                     // XT1 On
  UCSCTL6 |= XCAP_3;                        // Internal load cap

  // Loop until XT1,XT2 & DCO fault flag is cleared
  do
  {
    UCSCTL7 &= ~(XT2OFFG + XT1LFOFFG + XT1HFOFFG + DCOFFG);
                                            // Clear XT2,XT1,DCO fault flags
    SFRIFG1 &= ~OFIFG;                      // Clear fault flags
  }while (SFRIFG1&OFIFG);                   // Test oscillator fault flag

  // Configure RTC_A
  RTCCTL01 |= RTCTEVIE + RTCRDYIE + RTCBCD + RTCHOLD + RTCMODE;
                                            // RTC enable, BCD mode, RTC hold
                                            // enable RTC read ready interrupt
                                            // enable RTC time event interrupt

  RTCYEAR = 0x2010;                         // Year = 0x2010
  RTCMON = 0x4;                             // Month = 0x04 = April
  RTCDAY = 0x05;                            // Day = 0x05 = 5th
  RTCDOW = 0x01;                            // Day of week = 0x01 = Monday
  RTCHOUR = 0x10;                           // Hour = 0x10
  RTCMIN = 0x32;                            // Minute = 0x32
  RTCSEC = 0x45;                            // Seconds = 0x45

  RTCADOWDAY = 0x2;                         // RTC Day of week alarm = 0x2
  RTCADAY = 0x20;                           // RTC Day Alarm = 0x20
  RTCAHOUR = 0x10;                          // RTC Hour Alarm
  RTCAMIN = 0x23;                           // RTC Minute Alarm

  RTCCTL01 &= ~(RTCHOLD);                   // Start RTC calendar mode

  __bis_SR_register(LPM3_bits + GIE);       // Enter LPM3 mode with interrupts
                                            // enabled
  __no_operation();
}

#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=RTC_VECTOR
__interrupt void RTC_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(RTC_VECTOR))) RTC_ISR (void)
#else
#error Compiler not supported!
#endif
{
  switch(__even_in_range(RTCIV,16))
  {
    case RTC_NONE:                          // No interrupts
      break;
    case RTC_RTCRDYIFG:                     // RTCRDYIFG
      P1OUT ^= 0x01;                        // Toggles P1.0 every second
      break;
    case RTC_RTCTEVIFG:                     // RTCEVIFG
      __no_operation();                     // Interrupts every minute
      break;
    case RTC_RTCAIFG:                       // RTCAIFG
      break;
    case RTC_RT0PSIFG:                      // RT0PSIFG
      break;
    case RTC_RT1PSIFG:                      // RT1PSIFG
      break;
    case 12: break;                         // Reserved
    case 14: break;                         // Reserved
    case 16: break;                         // Reserved
    default: break;
  }
}

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MSP430F5418A能否动态写RTC寄存器？谢谢