Merge pull request ARMmbed#218 from paul-szczepanek-arm/add-mtu-to-gap

Add data length change to gap and ATT_MTU change to gatt client

Author: Donatien Garnier

BLE_GAP/source/main.cpp

@@ -568,6 +568,24 @@ class GapDemo : private mbed::NonCopyable<GapDemo>, public ble::Gap::EventHandle
         }
     }
 
+    /**
+     * Implementation of Gap::EventHandler::onDataLengthChange
+     */
+    virtual void onDataLengthChange(
+        ble::connection_handle_t connectionHandle,
+        uint16_t txSize,
+        uint16_t rxSize
+    ) {
+        printf(
+            "Data length changed on the connection %d.\r\n"
+            "Maximum sizes for over the air packets are:\r\n"
+            "%d octets for transmit and %d octets for receive.\r\n",
+            connectionHandle,
+            txSize,
+            rxSize
+        );
+    }
+
 private:
 
     /** Clean up internal state after last run, cycle to the next mode and launch it */

BLE_GattClient/source/main.cpp

@@ -43,7 +43,8 @@
  * indications and notification until the connection end.
  */
 class GattClientProcess : private mbed::NonCopyable<GattClientProcess>,
-                          public ble::Gap::EventHandler {
+                          public ble::Gap::EventHandler,
+                          public GattClient::EventHandler {
 
     // Internal typedef to this class type.
     // It is used as a shorthand to pass member function as callbacks.
@@ -118,6 +119,13 @@ class GattClientProcess : private mbed::NonCopyable<GattClientProcess>,
             return;
         }
 
+        // register as a handler for GattClient events
+        _client->setEventHandler(this);
+
+        // this might not result in a new value but if it does we will be informed through
+        // an call in the event handler we just registered
+        _client->negotiateAttMtu(_connection_handle);
+
         printf("Client process started: initiate service discovery.\r\n");
     }
 
@@ -170,6 +178,21 @@ class GattClientProcess : private mbed::NonCopyable<GattClientProcess>,
         }
     }
 
+    /**
+     * Implementation of GattClient::EventHandler::onAttMtuChange event
+     */
+    virtual void onAttMtuChange(
+        ble::connection_handle_t connectionHandle,
+        uint16_t attMtuSize
+    ) {
+        printf(
+            "ATT_MTU changed on the connection %d to a new value of %d.\r\n",
+            connectionHandle,
+            attMtuSize
+            /* maximum size of an attribute written in a single operation is one less */
+        );
+    }
+
 private:
 ////////////////////////////////////////////////////////////////////////////////
 // Service and characteristic discovery process.