我有一个图片18F4550如何从超声波传感器读取距离

Question

我有PIC 18f4550，需要用picBasic pro编写代码。
我正在连接直流电动机，超声波传感器和红外传感器...等
我已经做了所有事情，但仍然对如何连接超声波传感器感到困惑。

这是PIC中的超声针

trisb.3=0    'trigger ultrasound
trisb.4=1    ' Echo from Ultrasound

我需要一个示例代码

Answer 1

对其进行编程的基本步骤：

1-将TRIGGER提供给超声模块
2-听回声
收到ECHO HIGH时的3启动计时器
ECHO变为低电平时的4秒计时器
5次读取计时器值
6将其转换为距离
7-显示

距离计算

• 距离=速度*时间
  
• 设为超声波传感器与目标之间的距离
  
• 超声脉冲传播的总距离：2d（向前和向后）
  
• 空中声速：340 m / s = 34000 cm / s
  
• 因此，d =（34000 * Time）/ 2，其中时间=（TMR1H：TMR1L）/（1000000）
  
• 因此，d =（TMR1H：TMR1L）/58.82 cm
  
• TMR1H：TMR1L = TMR1L | （TMR1H << 8）
  

---

MikroC代码

// LCD module connections
sbit LCD_RS at RD2_bit;
sbit LCD_EN at RD3_bit;
sbit LCD_D4 at RD4_bit;
sbit LCD_D5 at RD5_bit;
sbit LCD_D6 at RD6_bit;
sbit LCD_D7 at RD7_bit;

sbit LCD_RS_Direction at TRISD2_bit;
sbit LCD_EN_Direction at TRISD3_bit;
sbit LCD_D4_Direction at TRISD4_bit;
sbit LCD_D5_Direction at TRISD5_bit;
sbit LCD_D6_Direction at TRISD6_bit;
sbit LCD_D7_Direction at TRISD7_bit;
// End LCD module connections

void main()
{
  int a;
  char txt[7];
  Lcd_Init();
  Lcd_Cmd(_LCD_CLEAR);          // Clear display
  Lcd_Cmd(_LCD_CURSOR_OFF);     // Cursor off

  TRISB = 0b00010000;           //RB4 as Input PIN (ECHO)

  Lcd_Out(1,1,"Developed By");
  Lcd_Out(2,1,"Mina Karam");

  Delay_ms(3000);
  Lcd_Cmd(_LCD_CLEAR);

  T1CON = 0x10;                 //Initialize Timer Module

  while(1)
  {
    TMR1H = 0;                  //Sets the Initial Value of Timer
    TMR1L = 0;                  //Sets the Initial Value of Timer

    PORTB.F0 = 1;               //TRIGGER HIGH
    Delay_us(10);               //10uS Delay
    PORTB.F0 = 0;               //TRIGGER LOW

    while(!PORTB.F4);           //Waiting for Echo
    T1CON.F0 = 1;               //Timer Starts
    while(PORTB.F4);            //Waiting for Echo goes LOW
    T1CON.F0 = 0;               //Timer Stops

    a = (TMR1L | (TMR1H<<8));   //Reads Timer Value
    a = a/58.82;                //Converts Time to Distance
    a = a + 1;                  //Distance Calibration
    if(a>=2 && a<=400)          //Check whether the result is valid or not
    {
      IntToStr(a,txt);
      Ltrim(txt);
      Lcd_Cmd(_LCD_CLEAR);
      Lcd_Out(1,1,"Distance = ");
      Lcd_Out(1,12,txt);
      Lcd_Out(1,15,"cm");
    }
    else
    {
      Lcd_Cmd(_LCD_CLEAR);
      Lcd_Out(1,1,"Out of Range");
    }
    Delay_ms(400);
  }
}