Help with sql clauses <= or >=

[eluser]johnpeace[/eluser]
[quote author="samuelr" date="1346113197"]

Code:

SELECT * FROM product WHERE produtos.preco >= 5

like this

Code:

$this->db->where('produtos.preco >=', $parameters);

in codeigniter 2.1.2 but is not working.

Could someone give me a hint, how to do this kind of sql?
[/quote]

What is the content of $parameters when the query runs?