MSP430FR6972串口在LPM3模式下接收数据异常

请您参考下下面的例程，SMCLK=1MHZ,115200

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//******************************************************************************
//  MSP430FR6x7x Demo - USCI_A0 External Loopback test @ 115200 baud
//
//  Description: This demo connects TX to RX of the MSP430 UART
//  The example code shows proper initialization of registers
//  and interrupts to receive and transmit data. If data is incorrect P1.0 LED is
//  turned ON.
//  ACLK = n/a, MCLK = SMCLK = BRCLK = default DCO = 1MHz
//
//
//                MSP430FR6972
//             -----------------
//       RST -|     P2.0/UCA0TXD|----|
//            |                 |    |
//           -|                 |    |
//            |     P2.1/UCA0RXD|----|
//            |                 |
//            |             P1.0|---> LED
//
//   Andreas Dannenberg
//   Texas Instruments Inc.
//   September 2014
//   Built with IAR Embedded Workbench V5.60 & Code Composer Studio V6.0
//******************************************************************************
#include <msp430.h>

volatile unsigned char RXData = 0;
volatile unsigned char TXData = 1;

int main(void)
{
  WDTCTL = WDTPW | WDTHOLD;                 // Stop watchdog

  // Configure GPIO
  P1OUT &= ~BIT0;                           // Clear P1.0 output latch
  P1DIR |= BIT0;                            // For LED on P1.0
  P2SEL0 |= BIT0 | BIT1;                    // USCI_A0 UART operation
  P2SEL1 &= ~(BIT0 | BIT1);

  // Disable the GPIO power-on default high-impedance mode to activate
  // previously configured port settings
  PM5CTL0 &= ~LOCKLPM5;

  // Configure USCI_A0 for UART mode
  UCA0CTLW0 = UCSWRST;                      // Put eUSCI in reset
  UCA0CTL1 |= UCSSEL__SMCLK;                // CLK = SMCLK
  UCA0BR0 = 8;                              // 1000000/115200 = 8.68
  UCA0MCTLW = 0xD600;                       // 1000000/115200 - INT(1000000/115200)=0.68
                                            // UCBRSx value = 0xD6 (See UG)
  UCA0BR1 = 0;
  UCA0CTL1 &= ~UCSWRST;                     // release from reset
  UCA0IE |= UCRXIE;                         // Enable USCI_A0 RX interrupt

  while (1)
  {
    while(!(UCA0IFG & UCTXIFG));
    UCA0TXBUF = TXData;                     // Load data onto buffer

    __bis_SR_register(LPM0_bits | GIE);     // Enter LPM0, interrupts enabled
  }
}

#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=USCI_A0_VECTOR
__interrupt void USCI_A0_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(USCI_A0_VECTOR))) USCI_A0_ISR (void)
#else
#error Compiler not supported!
#endif
{
  switch(__even_in_range(UCA0IV,USCI_UART_UCTXCPTIFG))
  {
    case USCI_NONE: break;
    case USCI_UART_UCRXIFG:
      RXData = UCA0RXBUF;                   // Read buffer
      if(RXData != TXData)                  // Check value
      {
        P1OUT |= BIT0;                      // If incorrect turn on P1.0
          while(1);                         // Trap CPU
      }
      TXData++;                             // increment data byte
      __bic_SR_register_on_exit(LPM0_bits); // Exit LPM0 on reti
      break;
    case USCI_UART_UCTXIFG: break;
    case USCI_UART_UCSTTIFG: break;
    case USCI_UART_UCTXCPTIFG: break;
  }
}

可以用。但要注意误码的情况。

用内部的dco做高频时钟源也是可以的。