view release on metacpan or  search on metacpan

HCSR04.xs  view on Meta::CPAN

#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <wiringPi.h>

int _setup(int trig, int echo){
 
    int setup_mode = -1;

    if (getenv("RPI_PIN_MODE"))
        setup_mode = atoi(getenv("RPI_PIN_MODE"));

    if (setup_mode == -1){
        if (wiringPiSetupGpio() == -1)
            exit(1);
    }
    else {
        /* setenv() copies its args; putenv() with a stack buffer left
           environ pointing at a dead frame once _setup() returned */
        char mode_value[12];
        sprintf(mode_value, "%d", setup_mode);
        setenv("RPI_PIN_MODE", mode_value, 1);
    }

    pinMode(trig, OUTPUT);
    pinMode(echo, INPUT);

    digitalWrite(trig, LOW);
    
    delay(30);
   
    return 1;
}
 
long _fetch(int trig, int echo) {

    digitalWrite(trig, HIGH);
    delayMicroseconds(20);
    digitalWrite(trig, LOW);

    // wait for echo

    while(digitalRead(echo) == LOW);

    // wait for echo end

    long start_time = micros();
    while(digitalRead(echo) == HIGH);

    long travel_time = micros() - start_time;

    return travel_time;
}

float _inch (int trig, int echo){
    long raw = _fetch(trig, echo);
    float inch = ((float)raw / 2) / 74;
    return inch;
}

float _cm (int trig, int echo){
    long raw = _fetch(trig, echo);
    float cm = (((float)raw / 2) / 74) * 2.54;
    return cm;
}

long _raw (int trig, int echo){
    return _fetch(trig, echo);
}

MODULE = RPi::HCSR04  PACKAGE = RPi::HCSR04

PROTOTYPES: DISABLE

int
_setup(trig, echo)
    int trig
    int echo

float
_inch(trig, echo)
    int trig