使用的MCU型号是MSP430F6721，电路板上面AUXVCC1和AUXVCC2引脚连接的是VCC，AUXVCC3引脚连接的是纽扣电池，这么连接对吗？
参考的例程如下：
#include <msp430.h>
int main (void)
{
WDTCTL = WDTPW | WDTHOLD; // Stop WDT
if (SYSRSTIV == SYSRSTIV_LPM5WU)
{
// When woken up from LPM3.5, reinit since LPMx.5 will cause a BOR.
PMMCTL0_H = PMMPW_H; // open PMM
PM5CTL0 &= ~LOCKIO; // Clear LOCKBAK and enable ports
PMMCTL0_H = 0x00; // close PMM
P1DIR |= BIT0; // Configure P1.0 as GPIO output
// Reconfigure RTC to read RTC registers
RTCCTL0_H = RTCKEY_H; // Unlock RTC_C module
RTCCTL1 |= RTCBCD | RTCHOLD; // BCD mode, RTC hold
RTCCTL1 &= ~(RTCHOLD); // Start RTC calendar mode
RTCCTL0_H = 0; // Lock RTC_C module
// If woken up at noon, set LED and stay loop there
if((RTCHOUR == 0x12)&&(RTCMIN == 0x00)&&(RTCSEC == 0x00))
{
P1OUT |= BIT0; // Set P1.0 on
while(1);
}
// If values do not match, blink LED fast
else
{
while(1) // continuous loop
{
P1OUT ^= BIT0; // XOR P1.0
__delay_cycles(20000); // Delay
}
}
}
// GPIO Port Configuration for lowest power configuration
P1OUT = 0x00;P2OUT = 0x00;P3OUT = 0x00;P4OUT = 0x00;P5OUT = 0x00;P6OUT = 0x00;
P7OUT = 0x00;P8OUT = 0x00;P9OUT = 0x00;PJOUT = 0x00;
P1DIR = 0xFF;P2DIR = 0xFF;P3DIR = 0xFF;P4DIR = 0xFF;P5DIR = 0xFF;P6DIR = 0xFF;
P7DIR = 0xFF;P8DIR = 0xFF;P9DIR = 0xFF;PJDIR = 0xFF;
// Initialize LFXT1
UCSCTL6 &= ~(XT1OFF); // Enable XT1
UCSCTL6 |= XCAP_3; // Internal load cap
// Loop until XT1, XT2 & DCO fault flag is cleared
do
{
UCSCTL7 &= ~(XT2OFFG | XT1LFOFFG | DCOFFG);
// Clear XT2,XT1,DCO fault flags
SFRIFG1 &= ~OFIFG; // Clear fault flags
} while (SFRIFG1 & OFIFG); // Test oscillator fault flag
// Configure RTC_C
RTCCTL0_H = RTCKEY_H; // Unlock RTC_C module
RTCCTL0_L |= RTCTEVIE; // Enable RTC time event interrupt
RTCCTL1 |= RTCBCD | RTCTEV_0 | RTCHOLD; // BCD mode, RTC hold, Set RTCTEV for 1 minute alarm
// event interrupt
RTCYEAR = 0x2011; // Year = 0x2011
RTCMON = 0x10; // Month = 0x10 = October
RTCDAY = 0x07; // Day = 0x07 = 7th
RTCDOW = 0x05; // Day of week = 0x05 = Friday
RTCHOUR = 0x11; // Hour = 0x11
RTCMIN = 0x59; // Minute = 0x59
RTCSEC = 0x45; // Seconds = 0x45
RTCCTL1 &= ~(RTCHOLD); // Start RTC calendar mode
RTCCTL0_H = 0; // Lock RTC_C module
// Enter LPM3.5
UCSCTL6 |= XT1OFF; // Turn off clock for LPMx.5 operation. ACLK will still
// remain active
PMMCTL0_H = PMMPW_H; // Open PMM Registers for write
PMMCTL0_L |= PMMREGOFF; // and set PMMREGOFF
__bis_SR_register(LPM4_bits | GIE); // Enter LPM3.5 mode with interrupts enabled
__no_operation();
// Code should NOT get here. This means that LPM3.5 was not properly entered.
// Ensure that an external power supply was ued. Or else JTAG will put the CPU
// in LPM0 mode.
// Stop the RTC
RTCCTL0_H = RTCKEY_H; // Unlock RTC_C module
RTCCTL1 |= RTCHOLD; // RTC hold
RTCCTL0_H = 0; // Lock RTC_C module
// Blink LED slowly if LPM3.5 not entered properly
while(1)
{
P1OUT ^= BIT0; // XOR P1.0
__delay_cycles(500000); // Delay
}
}
#pragma vector=RTC_VECTOR
__interrupt void rtc_isr(void)
{
switch (__even_in_range(RTCIV, 16))
{
case RTCIV_NONE: // No interrupts
break;
case RTCIV_RTCOFIFG: // RTCOFIFG
break;
case RTCIV_RTCRDYIFG: // RTCRDYIFG
break;
case RTCIV_RTCTEVIFG: // RTCEVIFG
PMMCTL0_H = PMMPW_H; // open PMM
PM5CTL0 &= ~LOCKIO; // Clear LOCKBAK and enable ports
PMMCTL0_H = 0x00; // close PMM
__bic_SR_register_on_exit(LPM4_bits); // Exit LPM4.5
__no_operation();
break;
case RTCIV_RTCAIFG: // RTCAIFG
break;
case RTCIV_RT0PSIFG: // RT0PSIFG
break;
case RTCIV_RT1PSIFG: // RT1PSIFG
break;
case 14: break; // Reserved
case 16: break; // Reserved
default: break;
}
}
关于这个例程有一些疑问
1，进入的是LPM3.5模式，RTC中断中为什么退出LPM4.5模式
2，什么情况下进入 if (SYSRSTIV == SYSRSTIV_LPM5WU) 语句，是断电吗
3，在 if (SYSRSTIV == SYSRSTIV_LPM5WU)语句中，并没有对RTC做中断设置，以前的RTC设置的
应该已经改变了吧，这样RTC还能进中断吗
4，此程序掉电后，再重新上电，RTC时钟是否丢失
以前的贴子中有提到一下内容
当VCC掉电的时候，为了保证RTC继续工作，可以按照如下设置来实现：
连接电源到主电源DVcc，Avcc，这里为3.3v，连接备用电池到Auxvcc1，Auxvcc3，
这里为3.0v锂电池，将不用的备用电源引脚Auxvcc2接地，并在固件代码中关闭它。
如下是供电电源切换并关闭Auxvcc2：
AUX0MD=0；
AUX1MD=0；
AUX2MD=1；
设置下一次选择的供电电源：
AUX0OK=1；AUX1OK=1；AUX2OK=0；AUX2PRIO=0；
在程序中当检测到切换到AUXVCC1时，保存当前工作进入LPM3.5模式，直到VCC电源恢复。
检测VCC是否恢复使用端口1或者2的中断功能检测。
能否详细讲解一下
