Write Application Test Code
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#define GET_DISTANCE _IOR('R',int)
int main(int argc,char *argv[]){
int fd;
unsigned long distance;
fd = open("/dev/HC_SR04",O_RDWR);
if(fd<0){
printf("open err..\n");
}
for( ;; ){
ioctl(fd,GET_DISTANCE,&distance);
printf("distance: %dcm..\n",distance);
sleep(1);
}
close(fd);
return 0;
}
Compile the application file, run the command aarch64-none-linux-gnu-gcc app.c -o app, copy the compiled executable file to DEBIX.
Test result
lTest the distance between the ultrasonic module and the object under test;
lPlace the object under test parallel to the ultrasonic module;
lExecute the application test code, run the command . /app;
lAdjust the distance between the object under test and the ultrasonic module can be seen:
NOTE:
lWhen using the ultrasonic module to measure the distance, try to keep the ultrasonic module parallel to the object under test.
lThe ultrasonic module measuring distance range is 2-400 cm, beyond or less than this range measurement will not be informative.
lWhen the measurement distance exceeds 400cm, print distance: -1cm.
