超声波

    #include "ioCC2530.h"     

    unsigned char counter;
    unsigned char buf[3];
    float distance;

    void SendASignal(void)
    {
    unsigned char i;
    P1 &= ~(1<<0);
    P1 |= (1<<0);  
    for(i=0;i<33;i++){
        asm("NOP");
        asm("NOP");
        asm("NOP");
        asm("NOP");
        asm("NOP");
        asm("NOP");
        asm("NOP");
        asm("NOP");
        asm("NOP");
        asm("NOP");
    }
    P1 &= ~(1<<0);
    } 
    void delay(void)
    {
    unsigned int i;
    unsigned char j;

    for(i=0;i<5000;i++)
    {
        for(j=0;j<200;j++)
        {
        asm("NOP");
        asm("NOP");
        asm("NOP");
        }
    }
    } 
    void UartTX_Send_String(unsigned char *Data,int len)   //串口发送函数
    {
        int j;
        for(j=0;j<len;j++)
        {
            U0DBUF = *Data++;   
            while(UTX0IF == 0);
            UTX0IF = 0;
        }
    }

    void UartTX_Send_Data(unsigned char Data,int len)   //串口发送函数
    {
        int j;
        for(j=0;j<len;j++)
        {
            U0DBUF = Data;   
            while(UTX0IF == 0);
            UTX0IF = 0;
        }
    }
    #pragma vector=URX0_VECTOR   //uart0中断函数
    __interrupt void uart0(void){
        URX0IF = 0; //清中断标志
    }

    #pragma vector=T1_VECTOR   //定时器1中断函数 50us
    __interrupt void Timer1(void){
        counter++;
        //P0_0=~P0_0;
    }

    void main( void )
    {
    P0DIR |= 0x01;  //设置P0.0为输出方式
    P2DIR |= 0x01;  //设置P2.0为输出方式
    P1SEL &= ~((1<<0)|(1<<1));//P1.0,P1.1为GPIO        
    P1DIR |= ((1<<0));        //P10为OUTPUT
    P1DIR &= ~(1<<1);         //P11为INPUT
    P1 &= ~(1<<0);

    P0_0 = 1; 
    P2_0 = 1;                    //熄灭LED
    counter = 0;
    CLKCONCMD &= ~0x40;          //选择32M晶振
    while(!(SLEEPSTA & 0x40));   //等待XSOC稳定
    CLKCONCMD = 0xb8;            //TICHSPD 128分频，CLKSPD 不分频
    SLEEPCMD |= 0x04;            //关闭不用的RC 振荡器
    T1CC0L = 6;
    T1CC0H = 0x00;               //比较值
    T1CTL = 0x33;                //通道0，不分频，up/down模式
    PERCFG = 0x00;               //位置1 P0 口
    P0SEL = 0x3c;                //P0 用作串口
    U0CSR |= 0x80;               //UART 方式
    U0GCR |= 10;                 //baud_e = 10;
    U0BAUD |= 216;               //波特率设为57600
    UTX0IF = 1;
    U0CSR |= 0X40;               //允许接收
    IEN0 |= 0x84;                //开总中断，接收中断   
    EA = 1;                      //开总中断
    T1IE = 1;                    //开定时器T1中断
    
    while(1){        
        P2_0=~P2_0;
        SendASignal();
        while(1){
        if(P1_1==1) break;
        }
        counter = 0;
        
        while(1){
        if(P1_1==0) break;
        }
        distance = counter;
        distance = (distance*50/1000000*340/2*100);
        counter = (unsigned int)distance;
        //counter保存高电平长度，单位为50us
        buf[0] = counter/100;
        buf[1] = (counter%100)/10;
        buf[2] = (counter%10);
        if(buf[0] > 0x9)
        buf[0] = buf[0] - 0xA + 'A';
        else
        buf[0] = buf[0] + '0';		      
        if(buf[1] > 0x9)
        buf[1] = buf[1] -0xA + 'A';
        else
        buf[1] = buf[1] + '0';
        if(buf[2] > 0x9)
        buf[2] = buf[2] -0xA + 'A';
        else
        buf[2] = buf[2] + '0';
        UartTX_Send_String("Ultrasonic = ",13);
        UartTX_Send_String(&buf[0],1);
        UartTX_Send_String(&buf[1],1);
        UartTX_Send_String(&buf[2],1);
        UartTX_Send_String("cm",2);
        UartTX_Send_String("\r\n",2);
        delay();
    }
    } // end of main()