T Nara / Mbed 2 deprecated Echo

Ultrasonic sensor used HC-SR04

Dependencies:   mbed

main.cpp

Committer:
tknara
Date:
2015-01-18
Revision:
0:6947b0547f9f

File content as of revision 0:6947b0547f9f:

#include "mbed.h"

Serial pc(USBTX,USBRX);
DigitalOut trig(p21);
DigitalOut testled(LED1);
DigitalIn echo(p22);
Timer t;
#define sonic_spead 343.595*100;// cm

int main() {
    double time;
    while(1) {
        testled = 0;
        t.reset();
        trig = 1;
        time = 0;
        wait_us(10);
        trig = 0;
        if (echo == 1) {
            t.start();
            while(1){
                if(echo == 0) {
                    testled = 1;
                    t.stop();
                    time = t.read();
                    time = time / 2.0 *sonic_spead;
                    pc.printf("%lfcm\n\r",time);
                    t.reset();
                    break;
                }
            }
        }
    }
}