如何在Firebird和PHP数据对象(PDO)中使用UTF-8

With mysql I can just do this to solve the problem:

$diveOptions = array(PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8"); // set names utf-8 and works well
$pdo = new PDO('mysql:host=mysql.example.com;dbname=example_db',"username","password",diveOptions); 

But I can't do the same with the firebird's pdo connection.

How can I solve this problem of UTF-8?

Already tried charset=utf8 in pdo configuration don t work too..

$str_conn = "firebird:dbname=C:\db\banco.gdb;charset=utf8;host=localhost";
$dbh = new PDO($str_conn, "SYSDBA", "masterkey");

In my db was set to nome like this:

DEFAULT CHARACTER SET NONE COLLATION NONE;