串口发送问题

问题： 串口发送问题
描述:

msp430      C语言

// 时钟默认情况
// FLL时钟      FLL选择 XT1
// 辅助时钟     ACLK选择 XT1          32768Hz
// 主系统时钟   MCLK选择 DCOCLKDIV    8000000Hz
// 子系统时钟   SMCLK选择 DCOCLKDIV   8000000Hz
// UART时钟选择 SMCLK
#include <msp430f5438a.h>
#include <stdio.h>
#include <string.h>
void clock_config(void);
void select_xt1(void);
void dco_config(void);
void uart_config(void);
unsigned char buffer[] = "MSP430F5438A";
int main(void)
{
    clock_config();                             // 初始化时钟
    uart_config();                              // 串口设置
    _EINT();                                    // 打开全局中断
    P2DIR |= BIT5;                              // P4.0输出
   // printf("Hello MSP430!\r\n");
    while(1)
    {
        for(int i = 0; i < sizeof(buffer); i++)
         {
            UCA0TXBUF = buffer[i];
            while(!UCA0IFG&UCTXIFG);
            __delay_cycles(1000000);
            
         }
    }
}
void clock_config(void)
{
    WDTCTL = WDTPW + WDTHOLD;                   // 停止看门狗
    select_xt1();                               // 选择XT1
    dco_config();                               // ACLK = XT1 = 32.768K
                                                // MCLK = SMCLK = 8000K
}
void select_xt1(void)
{
    // 启动XT1
    P7SEL |= 0x03;                              // P7.0 P7.1 外设功能
    UCSCTL6 &= ~(XT1OFF);                       // XT1打开
    UCSCTL6 |= XCAP_3;                          // 内部电容
    do
    {
        UCSCTL7 &= ~XT1LFOFFG;                  // 清楚XT1错误标记
    }while (UCSCTL7&XT1LFOFFG);                 // 检测XT1错误标记
}
void dco_config(void)
{
    __bis_SR_register(SCG0);                    // 禁止FLL功能
    UCSCTL0 = 0x0000;                           // Set lowest possible DCOx, MODx
    UCSCTL1 = DCORSEL_5;                        // DCO最大频率为16MHz
    UCSCTL2 = FLLD_1 + 243;                     // 设置DCO频率为8MHz
                                                // MCLK = SMCLK= Fdcoclkdiv = (N+1)X(Ffllrefclk/n)
                                                // N为唯一需要计算的值
                                                // Ffllrefclk FLL参考时钟，默认为XT1
                                                // n取默认值，此时为1
                                                // (243 + 1) * 32768 = 8MHz
    __bic_SR_register(SCG0);  &nb