diff --git a/avr/shared.asm b/avr/shared.asm
new file mode 100644
index 0000000..d4bdc0d
--- /dev/null
+++ b/avr/shared.asm
@@ -0,0 +1,28 @@
+; ***************************************************************************
+; copyright   : (C) 2023 by Martin Preuss
+; email       : martin@libchipcard.de
+;
+; ***************************************************************************
+; * This file is part of the project "AqHome".                              *
+; * Please see toplevel file COPYING of that project for license details.   *
+; ***************************************************************************
+
+
+
+; ***************************************************************************
+; code
+
+.cseg
+
+
+Shared_Clc_Ret:
+  clc
+  ret
+
+
+Shared_Sec_Ret:
+  sec
+  ret
+
+
+