File content as of revision 7:c763b5d61dee:

#include "mbed.h"
#include "ultrasonic.h"

PwmOut TX1(D9);                             // Use pin D9
DigitalOut TX2(D8);                         // Use pin D8
DigitalOut HVoff(D6);                       // Use pin D6
InterruptIn signal(D7);                     // Use pin D7
Timeout to1;
Timer t1;
Serial pc(SERIAL_TX, SERIAL_RX);

float previous = 1;
int US_count = 0;
float US_buffer[100];

void TX1_send(){
    
    previous = 1;
    HVoff = 0;
    TX1.period(0.0000252);                  // Set the period of TX1 to 25.2us (39,682kHz)
    TX1.pulsewidth(0.0000116);              // Set the pulsewidth of TX1 to 11.6us (ON)
    wait(0.0002016);                        // Waits 201.6us
    TX1 = 0;
    t1.reset();
    wait(0.0000116);
    HVoff = 1;
    to1.attach(TX1_send,0.1);               // Sends for 1000us
    }


void signal_reciev(){
    
    float _time = t1.read();
    
    if (_time<0.006 && _time>0.0008){
        
        if (t1.read()>previous){
            }
        else{
            previous = _time;  
            US_buffer[US_count] = 34613*_time/2;
            pc.printf("Forste %d", US_count);
            US_count++;           
            }
        }
    }

float get_avg(){
        signal.fall(&signal_reciev);
        TX2 = 1;
        TX1_send(); 
        
        while(US_count<20){pc.printf("\r");}
        
        
        float sum = 0;
        
        for(int i=0;i<20;i++){
            
        sum += US_buffer[i];
        US_buffer[i] = 0;
        }
        US_count = 0;
        return sum/20;
    }
int main() {
     t1.start();
    float nks = get_avg();
   pc.printf("Avg = %f\r\n",nks);
    
    }