USCI UART的波特率问题..

只看该作者 · 2013-5-27 09:15

4M晶振,要9600波特率...

用波特率计算工具算得:UBR1=0X01;UBR0=0XA0;UCA0MCTLW=0XC000;

怎么不对呢...和PC联系不上...
void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                // stop watchdog

  // XT1 Setup

  PJSEL0 |= BIT4 + BIT5;

  CSCTL0_H = 0xA5;
  CSCTL1 |= DCOFSEL0 + DCOFSEL1;          // Set max. DCO setting
  CSCTL2 = SELA_0 + SELS_3 + SELM_3;       // set ACLK = XT1; MCLK = DCO=smlk
  CSCTL3 = DIVA_2 + DIVS_0 + DIVM_0;       // set all dividers  1MHZ
  CSCTL4 |= XTS;             //high speed mode
  CSCTL4&=~XT1DRIVE_3;
  CSCTL4 &= ~XT1OFF;

  do
  {
CSCTL5 &= ~XT1OFFG;
                                          // Clear XT1 fault flag
SFRIFG1 &= ~OFIFG;
  }while (SFRIFG1&OFIFG);                // Test oscillator fault flag

  // Configure UART pins
  P2SEL1 |= BIT0 + BIT1;
  P2SEL0 &= ~(BIT0 + BIT1);

  P3OUT=0;
  P3DIR|=BIT4+BIT5+BIT6+BIT7;
  // Configure UART 0
  UCA0CTL1 |= UCSWRST;
  UCA0CTL1 = UCSSEL_1;                   // Set ACLK = 4MHZ as UCBRCLK
  UCA0BR0 = 0xa0;                            // 9600 baud
  UCA0BR1 = 0x01;
  UCA0MCTLW |= 0xc000;

  UCA0CTL1 &= ~UCSWRST;                   // release from reset
  UCA0IE |= UCRXIE;                      // Enable RX interrupt

  _EINT();