raspberrypi/gpio/ultrasound.c

78 lines
1.6 KiB
C
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2020-09-10 13:23:23 +08:00
/*
*
*
*/
#include <wiringPi.h>
#include <sys/time.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
int is_num(int n, char *argv[])
{
int j = 0;
int i;
char parameter[10];
strcpy(parameter, argv[n]);
int len = strlen(parameter);
for (i = 0; i < len; i++) {
if (parameter[i] <= 57 && parameter[i] >= 48) //0~9的ASCII码是48~57
{
j++;
}
}
if (j == len) {
return 1;
} else {
return 0;
}
}
int main(int argc, char *argv[])
{
if (argc != 3) {
printf("Parameter error.\n");
exit(1);
}
if (is_num(1, argv) == 0) {
printf("Parameter error, Parameter 1 is the tring pin\n");
exit(1);
}
if (is_num(2, argv) == 0) {
printf("Parameter error, Parameter 2 is the echo pin\n");
exit(1);
}
int pin_tring = atol(argv[1]);
int pin_echo = atol(argv[2]);
struct timeval tv1;
struct timeval tv2;
long start_time, stop_time;
float distance;
if (wiringPiSetup() == -1) {
exit(0);
return 0;
}
digitalWrite(pin_tring, LOW);
digitalWrite(pin_tring, HIGH);
delayMicroseconds(10);
digitalWrite(pin_tring, LOW);
while (!(digitalRead(pin_echo) == 1)) ;
gettimeofday(&tv1, NULL);
while (!(digitalRead(pin_echo) == 0)) ;
gettimeofday(&tv2, NULL);
start_time = tv1.tv_sec * 1000000 + tv1.tv_usec;
stop_time = tv2.tv_sec * 1000000 + tv2.tv_usec;
distance = (float)(stop_time - start_time) / 1000000 * 34000 / 2;
printf("%0.0f\n", distance);
return distance;
}