MSP430f5529的HC-SR04模块的超声波测距的代码

以下是MSP430f5529使用HC-SR04模块进行超声波测距的代码：

#include "msp430.h"

#define TRIG BIT0   //P1.0
#define ECHO BIT1   //P1.1

void delay_us(unsigned int us){
    unsigned int i;
    for(i=0; i<us; i++){
        __delay_cycles(1);
    }
}

unsigned int get_distance(void){
    unsigned int distance;
    unsigned int time;
    P1OUT &= ~TRIG;
    delay_us(2);
    P1OUT |= TRIG;
    delay_us(10);
    P1OUT &= ~TRIG;

    while((P1IN & ECHO) == 0);
    TA0CTL |= MC_1;
    TA0R = 0;
    while((P1IN & ECHO) != 0);
    time = TA0R;
    TA0CTL &= ~MC_1;

    distance = time / 58;
    return distance;
}

void main(void){
    WDTCTL = WDTPW + WDTHOLD;
    P1DIR |= TRIG;
    P1DIR &= ~ECHO;
    P1SEL |= ECHO;
    P1SEL2 |= ECHO;

    TA0CTL |= TASSEL_2 + ID_0 + MC_0 + TACLR;
    TA0CCTL0 |= CM_1 + CCIS_0 + CAP;
    TA0CCTL0 &= ~CCIE;

    while(1){
        unsigned int distance = get_distance();
    }
}

代码中使用了定时器TA0来计算超声波的回响时间，同时使用了P1.0和P1.1口分别控制HC-SR04模块的触发和接收。get_distance函数返回测量到的距离。