File content as of revision 1:f4ae12a86f80:

#include "mbed.h"
#include "hcsr04.h"

Serial to_main(dp4,dp5);
//Serial pc(USBTX,USBRX);

HCSR04 front(dp24,dp25);
HCSR04 back(dp22,dp23);
HCSR04 right(dp20,dp21);
HCSR04 left(dp18,dp19);



int main() {
    char dist[4]={0};
    //to_main.baud(19200);
    while(1) {
        front.start();
        back.start();
        right.start();
        left.start();
        if(front.get_dist_cm()>255)
            dist[0]=255;
        else
            dist[0]=front.get_dist_cm();
        if(back.get_dist_cm()>255)
            dist[1]=255;
        else
            dist[1]=back.get_dist_cm();
        if(right.get_dist_cm()>255)
            dist[2]=255;
        else
            dist[2]=right.get_dist_cm();
        if(left.get_dist_cm()>255)
            dist[3]=255;
        else
            dist[3]=left.get_dist_cm();

        to_main.putc(1);
        for(int i=0;i<4;i++){
            to_main.putc(dist[i]);
        }
        //pc.putc('\n');
    }
}