Allow Updating ComObject with Sending On Modification Only

src/knx/group_object.cpp

@@ -279,3 +279,18 @@ void GroupObject::valueNoSend(const KNXValue& value, const Dpt& type)
 
     KNX_Encode_Value(value, _data, _dataLength, type);
 }
+
+void GroupObject::valueSendChangedOnly(const KNXValue& value, const Dpt& type)
+{
+    // save current value
+    const uint8_t oldLength = _dataLength;
+    uint8_t* old = new uint8_t[_dataLength];
+    memcpy(old, _data, oldLength);
+
+    // update value in com-object, without sending to bus
+    valueNoSend(value, type);
+
+    // only when raw data differs trigger sending
+    if (oldLength!=_dataLength || memcmp(old, _data, oldLength)!=0)
+        objectWritten();
+}

src/knx/group_object.h

@@ -166,6 +166,16 @@ class GroupObject
      * The parameters must fit the group object. Otherwise it will stay unchanged.
      */
     void valueNoSend(const KNXValue& value, const Dpt& type);
+
+    /**
+     * set the current value of the group object and only when resulting value differes, changes the state of the group object to ::WriteRequest.
+     * @param value the value the group object is set to
+     * @param type the datapoint type used for the conversion.
+     * 
+     * The parameters must fit the group object. Otherwise it will stay unchanged.
+     */
+    void valueSendChangedOnly(const KNXValue& value, const Dpt& type);
+
     /**
      * set the current value of the group object.
      * @param value the value the group object is set to