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问 #include "MSP430x14x.h"

void main(void)
{
unsigned int i;
WDTCTL = WDTPW + WDTHOLD; // 停止看门狗

BCSCTL1 = XT2OFF; // 打开XT2 8MHz高频晶体

do //等待高频晶振完全启动
{
IFG1 &= ~OFIFG; // 清除OSCFault标志
for (i = 0xFF; i > 0; i--);
}
while ((IFG1 & OFIFG) == OFIFG); // 如果OSCFault =1

BCSCTL2 = SELM1+SELS; // MCLK,SMCLK = XT2

ME1 |= USPIE0; // Enable USART0 SPI mode
UTCTL0 = CKPH+SSEL0+SSEL1+STC; // SMCLK, 3-pin mode
UCTL0 = CHAR+SYNC+MM; // 8-bit SPI Master **SWRST**
UBR00 = 0x8; // UCLK/8
UBR10 = 0x0; // 0
UMCTL0 = 0x00; // no modulation
P3SEL |= 0x0E; // P3.1-3 SPI option select
P3DIR |= 0x01; // P3.0 output direction
_EINT(); // Enable interrupts

while (1)
{
//unsigned i;
//for (i = 0xFFFF; i > 0; i--); // Delay
//while ((IFG1 & UTXIFG0) == 0); // USART0 TX buffer ready?
//P3OUT &= ~0x01; // Latch data into 'HC165
//P3OUT |= 0x01;
TXBUF0 = 0xAA;//RXBUF0; // RXBUF0 to TXBUF0
_NOP();
_NOP();
_NOP();
_NOP();
_NOP();
_NOP();
_NOP();
_NOP();
_NOP();
_NOP();
}
} 答 1: 请帮忙。 答 2: BCSCTL1 = XT2OFF; 答 3: BSCTL1=XT2OFF 是打开晶体的意思(置位)。