bluetooth: Add CPF attribute to BAS battery level.

BAS v1.1, section 3.1.2.1 notes that a CPF should be added if the device has more that one instance of the Battery Service, so add one with the `main` description so that apps can add additional Battery Level services with other descriptions, e.g. `auxiliary`. Signed-off-by: Peter Johanson <[email protected]>
zmkfirmware · Dec 1, 2023 · 1ae0eb5 · 1ae0eb5
1 parent 9b9cf36
commit 1ae0eb5
Showing 1 changed file with 12 additions and 0 deletions.
diff --git a/subsys/bluetooth/services/bas.c b/subsys/bluetooth/services/bas.c
@@ -47,6 +47,17 @@ static ssize_t read_blvl(struct bt_conn *conn,
 				 sizeof(lvl8));
 }
 
+/* Constant values from the Assigned Numbers specification:
+ * https://www.bluetooth.com/wp-content/uploads/Files/Specification/Assigned_Numbers.pdf?id=89
+ */
+static const struct bt_gatt_cpf level_cpf = {
+	.format = 0x04,        /* uint8 */
+	.exponent = 0x0,
+	.unit = 0x27AD,        /* Percentage */
+	.name_space = 0x01,    /* Bluetooth SIG */
+	.description = 0x0106, /* "main" */
+};
+
 BT_GATT_SERVICE_DEFINE(bas,
 	BT_GATT_PRIMARY_SERVICE(BT_UUID_BAS),
 	BT_GATT_CHARACTERISTIC(BT_UUID_BAS_BATTERY_LEVEL,
@@ -55,6 +66,7 @@ BT_GATT_SERVICE_DEFINE(bas,
 			       &battery_level),
 	BT_GATT_CCC(blvl_ccc_cfg_changed,
 		    BT_GATT_PERM_READ | BT_GATT_PERM_WRITE),
+	BT_GATT_CPF(&level_cpf),
 );
 
 static int bas_init(const struct device *dev)