BUenas alguien sabe como convertir unexcel a csv con comas logre leer el excel con el php este es el script , pero quiero convertirlo a csv

require_once 'CompoundDocument.inc.php';
require_once 'BiffWorkbook.inc.php';

$fileName = "data.xls";

if (!is_readable ($fileName)) die ('Cannot read ' . $fileName);

$doc = new CompoundDocument ('utf-8');
$doc->parse (file_get_contents ($fileName));
$wb = new BiffWorkbook ($doc);
$wb->parse ();

foreach ($wb->sheets as $sheetName => $sheet)
{
echo '<h1>' . $sheetName . '</h1>';
echo '<table cellspacing = "0">';
for ($row = 0; $row < $sheet->rows (); $row ++)
{
echo '<tr>';
for ($col = 0; $col < $sheet->cols (); $col ++)
{
if (!isset ($sheet->cells [$row][$col])) continue;
$cell = $sheet->cells [$row][$col];
echo '<td style = "' . $cell->style->css () . '" rowspan = "' . $cell->rowspan . '" colspan = "' . $cell->colspan . '">';
echo is_null ($cell->value) ? '&nbsp;' : $cell->value;
echo '</td>';
}
echo '</tr>';
}
echo '</table>';
}