Alcohol Gas Detector

<?php
 
include "/lib/sd_340.php";
$pid = pid_open("/mmap/adc0");
$uio = pid_open("/mmap/uio0");
pid_ioctl($uio, "set 0 mode out");
 
function pwm_buzzer($time)
{
    if($time == 0)
    {
        while(ht_ioctl(1, "get state"))
        ht_ioctl(1, "stop");
        
        ht_ioctl(1, "set div ms"); 
        ht_ioctl(1, "set mode output pwm"); 
        ht_ioctl(1, "set count 0 10000"); 
    }
    else
    {
        ht_ioctl(1, "stop");    
        ht_ioctl(1, "set div ms"); 
        ht_ioctl(1, "set mode output pwm"); 
        ht_ioctl(1, "set count $time $time"); 
        ht_ioctl(1, "start"); 
    }
}
 
$add = 0;
$adc_val = 0;
pid_write($uio, 0x00);
 
while(1)
{
    for($i = 0; $i < 10; $i++)
    {
        pid_read($pid, $adc_val); 
        $add += $adc_val;
    }
    $avr = $add / 10;
    $real = (($avr / 4095.0) * 3.3) ;
    printf("level : %.2f\r\n\r\n", $real);
    $buzzer = (int)round ((1.0 / $avr) * 100000);
    
    if($real <= 0.7)
    {
        pwm_buzzer(0);
        pid_write($uio, 0x00);
    }
    else
    {
        pid_write($uio, 0x01);
        pwm_buzzer($buzzer);
    }
    $add = 0;
sleep(1);
}
?>