In a large bowl, combine the peaches, flour, honey, lemon juice and salt; let stand for 15 minutes. Fold in blackberries. Transfer to a 13-in. x 9-in. x 2-in. baking dish coated with cooking spray.
For topping, in a large bowl, combine the flour, sugar, baking powder, salt and baking soda. Cut in butter until crumbly. Make a well in the center; pour in buttermilk. Stir just until a soft dough forms. Drop by tablespoonfuls over fruit mixture; sprinkle with coarse sugar.
Bake at 400° for 40-45 minutes or until filling is bubbly and a toothpick inserted in topping comes out clean. Serve warm. Yield: 12 servings.