Create star pyramid

//I want to create a star pyramid..but it not work..can someone assist me to solve it..

This is the code

<?php

for ($x=1;$x<=5;$x++)
{
    echo "<center>";
    for ($y=1;$y=$x;$y++)
    {
        echo "*";
    }
    echo "<br>";
}
?>

This is the output

---

Fatal error: Maximum execution time of 30 seconds exceeded in C:\xampp\htdocs\StarPyramid2.php on line 6