#include <msp430.h> long current_time;//最近一次测得时间 /*MyPro*/ #define LED_1 BIT0                      #define SW_2 BIT3                       #define TA1_1 BIT2                      //TA0.1 HC-SR04 Echo #define TRIG BIT4                       //HC-SR04 Trig #define ACCU_GRD 7   //Accuracy Grade "xxx.x"+'\0'                    #define MIN_UNIT_TO1M 1000  //1 m to 1 mm /*TIMER0*/ #define SOUR_CLK  1045000 #define DIV_CLK_1  1 #define SYS_CLK_SIG_1  SOUR_CLK/DIV_CLK_1 #define DISTANCE 45//dm #define TIMER_RIG_MAX 0xffff #define MAX_TIME_1 DISTANCE*2/34*SYS_CLK_SIG_1 #ifdef  MAX_TIME_1 #define SYS_CLK SYS_CLK_SIG_1 #endif #define UART_TXD BIT2  void init_timer1()                      {   P2SEL |= TA1_1;                       //TA1.1 CCI1B be used                            P2DIR &= ~TA1_1;   TA1CTL = MC_0 + TASSEL_2;             //TimerA_0 stop mode,clock=1Mhz                       TA1CCTL1 = CCIE + SCCI + CCIS_1 + SCS + CAP + CM_2; //TA0CC1 capture mode + down edge } /*UART*/ void init_uart()                        //USCI 初始化函数 {   UCA0CTL1 |= UCSWRST;                  //初始化串口寄存器                      UCA0CTL1 |= UCSSEL_2;                 //选择子系统时钟 1.045MHz   UCA0BR0 = 0x6d;                       //波特率为9600   UCA0BR1 = 0x00;   P1SEL |= UART_TXD;   P1SEL2 |= UART_TXD;   P1DIR |= UART_TXD;                    //将P1.2设为第二功能   UCA0CTL1 &= ~UCSWRST;                 //初始化结束 } long cal_distance()                     //通过测得时间计算距离 {  return (long)((340*(0.5000*current_time/SYS_CLK)*MIN_UNIT_TO1M)); } void delay()    //粗略延迟 {  unsigned char i,j;  for(i=124;i>0;i--)   for(j=8;j>0;j--); } static char * translater(long distance)  //将测得的距离以字符串形式存储 {   static char trans[ACCU_GRD];   int i;   long f;   trans[0]=' ';   if(distance)   for(i=1,f=MIN_UNIT_TO1M;i<ACCU_GRD-1;i++)            //转化核心算法   {     if(i==4)     {       trans[i] = '.';                         continue;     }     trans[i] = '0'+ distance/f;     distance %= f;     f /= 10;   }   trans[ACCU_GRD-1] = '\0';                      return trans; } void once_pro()                         //发一次超声波 {  if(TA1CCTL1 & COV)   TA1CCTL1 &= ~COV;  if(!(P1IN & BIT3))                     {    TA1R = 0;    P1OUT |= TRIG;                       //Trig 10 us 高电平    _EINT();    TA1CTL |= MC_2;   //continue mode    P1OUT &= ~TRIG;    P1OUT |= LED_1;    while(TA1CCTL1 & CCIFG);          //等待 捕捉中断结束  }  else  {    P1OUT &= ~LED_1;    _DINT();  }     } void uart_txstring(char *string)        //UART_TX 发送一个串 {   int i=0;   while(string[i++])   {    switch (i)      //过滤无效 '0'     {      case 1:if(string[i]=='0') continue;      case 2:if(string[i]=='0'&&string[i-1]=='0') continue;     }     UCA0TXBUF = string[i];     delay();   } } /*UART_ISR*/ #pragma vector = USCIAB0TX_VECTOR __interrupt void usci_txdistance()      //向 PC 发送 测得的距离 {   uart_txstring("\n\r");   uart_txstring(" Current ");   uart_txstring(" distance: ");   uart_txstring(translater(cal_distance()));   uart_txstring(" cm");   IE2 &= ~UCA0TXIE; } /*TIMER0_INT_ISR*/ #pragma vector = TIMER1_A1_VECTOR __interrupt void capture()            {  current_time = TA1CCR1;  TA1CTL &= ~MC_2;  TA1CCTL1 &= ~CCIFG;           //清CC1中断标志位          IE2 |= UCA0TXIE; } /*Main*/ void main() {   WDTCTL = WDTPW + WDTHOLD;              //关狗   DCOCTL = 0;                              BCSCTL1 = CALBC1_1MHZ;   DCOCTL  = CALDCO_1MHZ;   P1OUT = 0;   P2OUT = 0;   P1REN |= SW_2;   P2REN |= TA1_1;   P1OUT |= SW_2;   P1DIR &= ~SW_2;                          P1DIR = TRIG + LED_1;   init_timer1();   init_uart();   while(1)   {      int c = 8;    while(c--)    delay();    if(TA1CCTL1 & CCIFG)    TA1CCTL1 &= ~CCIFG;    once_pro();   } }