초음파 센서 wiring pi 버전

파이썬만 보여서 대충 바꿔봄.

대충.. 2cm ~ 400cm로 제한을 줘야하나..

데이터 시트는 아래 링크 참조해서 작성

[링크 : https://docs.google.com/document/d/1Y-yZnNhMYy7rwhAgyL_pfa39RsB-x2qR4vP8saG73rE/edit]

시간재는건 아래 참조

[링크 : http://hwangdo83.tistory.com/123]

$ cat sr04.c /*  *  dht11.c:  *      Simple test program to test the wiringPi functions  *      DHT11 test  */ #include <wiringPi.h> #include <stdio.h> #include <stdlib.h> #include <stdint.h> #include <sys/time.h> #define TRIG_PIN        4 #define ECHO_PIN        5 void read_sr04_dat() {         int counter = 0;         struct timeval start_point, end_point;         double operating_time;         double len;         pinMode(TRIG_PIN, OUTPUT);         pinMode(ECHO_PIN, INPUT);         digitalWrite(TRIG_PIN, LOW); //      delay(500); // 500 msec         digitalWrite(TRIG_PIN, HIGH);         delayMicroseconds( 10 );         digitalWrite(TRIG_PIN, LOW);         while ( digitalRead(ECHO_PIN) == LOW)         {                 counter++;                 delayMicroseconds( 1 );                 if ( counter == 38000 )                 {                         return;                 }         }         gettimeofday(&start_point, NULL);         while ( digitalRead(ECHO_PIN) == HIGH)         {                 counter++;                 delayMicroseconds( 1 );                 if ( counter == 38000 )                 {                         return;                 }         }         gettimeofday(&end_point, NULL);         operating_time = (double)(end_point.tv_sec)+(double)(end_point.tv_usec)/1000000.0-(double)(start_point.tv_sec)-(double)(start_point.tv_usec)/1000000.0;         len = operating_time * 34300 / 2;         printf("%f sec %4.2f cm %d\n",operating_time, len, counter); } int main( void ) {         if ( wiringPiSetup() == -1 )                 exit( 1 );         while ( 1 )         {                 read_sr04_dat();                 delay( 100 ); /* wait 1sec to refresh */         }         return(0);

한번 보냈는데 못 재면 이상한 값을 뱉는건 왜그럴까나..