In a large bowl, stir together the flours, bran, baking powder, baking soda and salt. Add the buttermilk, oil, maple syrup, eggs and vanilla and whisk until well blended.
Preheat your waffle iron and spray it with nonstick spray or brush it with oil. Cook the batter according to the manufacturers directions (I cook about a ladleful in a thick Belgian waffle maker) until golden brown. Keep them warm in a 200F oven while you cook the rest.