Hi everyone, I'm trying to capture the value to determine the distance of an object using ultrasonic sensor,but getting the distance as 0 on lcd, checked the status of trigger pin in oscilloscope getting the pulse in this pin but not on echo pin.

Assigned Trigger as Output & Echo as Input, below is the code:

Connected  ECHO_PIN to PIN 16 & TRIGGER_PIN to PIN 12

uC: LPC2148
Compiler : Keil uvision 5.1

Pclk: 60Mhz

#include<LPC214x.h>
#include<stdio.h>
#include "lcd.h"

#define PRESCALE 60
#define TIMER_TICK_1_MS (59999) /* VPB at 60 MHz clock */

#define ECHO_PIN (1 << 16)     //INPUT PIN[PIN 16]
#define TRIGGER_PIN (1 << 17)  //OUTPUT PIN[PIN 12]

void initTimer(void);
void delay3(int);
unsigned char buf[16] = {0};
void delay_ms(unsigned int count);

void initTimer()
{

 T1TCR = 0x00;  /* ensure timer 1 is off */
 /* set timer counter and prescale counter */
 T1TC = 0x0;
 T1PC = 0x0;

 /* set prescale and match values to give 1 ms "tick" */
 T1PR = 0x0;
 T1MR0 = TIMER_TICK_1_MS;

 /* set control to interrupt on MR0 match, and reset to 0 (i.e. "tick") */
 T1MCR = 0x3;

 /* go start timer 1... */
 T1TCR = 0x1;

}

void delay_ms(unsigned int count)
{
  unsigned int j=0,i=0;
  for(j=0;j<count;j++)
  {
    for(i=0;i<3000;i++);
  }
}

int main()
{
init_lcd();

IO1DIR &= ~(1<<16); //Echo pin
IO1DIR |= (1<<17); //trigger pin

initTimer();
lcd_clear();

        while(1)
        {
    long time,dist;
               

    IO1SET = 1<<17; //send high on trigger pin

    delay_ms(1000); //delay for 10us
    IO1CLR = 1<<17; // send low after 10us

    T1TCR = 0x01;  //Enable Timer1
    if(T1CR0 == 0)
    {
    delay_ms(100);
    } //wait for rising edge to occur on echo pin
    delay_ms(3);          //wait for debounce
    if(T1CR0 == 0)
    {
    time = T1CR0; //read value of CR0 reg
    dist = (time*340)/2; //dist in meters
    IO1SET = 1<<16;
    delay_ms(100);
    IO1CLR = 1<<16;
    sprintf((char *)buf, "dist:%d cm",dist);
    lcd_putstring(1, (char *)buf);
    }
     else

    T1TCR = 0x00; //disable Timer1

        }
    
}

Thank you,

Akashh

Why don't you get a pulse on the echo pin?

Is the trigger pulse within specification?

Have you understood your sensor?

Thank you for the response sir, and have referred the working principle 

of sensor, will work on the echo pin.

>>delay_ms(1000); //delay for 10us

That is not a 10 us delay - that would be 1 second!