diff --git a/src/knx/group_object.cpp b/src/knx/group_object.cpp index 6898ba5..b7c74d8 100644 --- a/src/knx/group_object.cpp +++ b/src/knx/group_object.cpp @@ -279,3 +279,27 @@ void GroupObject::valueNoSend(const KNXValue& value, const Dpt& type) KNX_Encode_Value(value, _data, _dataLength, type); } + +bool GroupObject::valueNoSendCompare(const KNXValue& value, const Dpt& type) +{ + if (_commFlag == Uninitialized) + { + // always set first value + this->valueNoSend(value, type); + return true; + } + else + { + // convert new value to given dtp + uint8_t newData[_dataLength]; + memset(newData, 0, _dataLength); + KNX_Encode_Value(value, newData, _dataLength, type); + + // check for change in converted value / update value on change only + const bool dataChanged = memcmp(_data, newData, _dataLength); + if (dataChanged) + memcpy(_data, newData, _dataLength); + + return dataChanged; + } +} \ No newline at end of file diff --git a/src/knx/group_object.h b/src/knx/group_object.h index 88ce274..7c9191b 100644 --- a/src/knx/group_object.h +++ b/src/knx/group_object.h @@ -166,6 +166,19 @@ class GroupObject * The parameters must fit the group object. Otherwise it will stay unchanged. */ void valueNoSend(const KNXValue& value, const Dpt& type); + + /** + * Check if the value (after conversion to dpt) will differ from current value of the group object and update if necessary. + * Use this method only, when the value change is relevant, otherwise valueNoSend(const KNXValue&, const Dpt&) will do the same (without overhead for comparing) + * @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. + * + * @returns true if the value of the group object has changed + */ + bool valueNoSendCompare(const KNXValue& value, const Dpt& type); + /** * set the current value of the group object. * @param value the value the group object is set to