diff --git a/avr/common/0BUILD b/avr/common/0BUILD
index 4d18df1..26bb9eb 100644
--- a/avr/common/0BUILD
+++ b/avr/common/0BUILD
@@ -17,6 +17,7 @@
     utils_copy_from_flash.asm
     utils_copy_sdram.asm
     utils_initial_wait.asm
+    utils_io.asm
     utils_wait.asm
     utils_wait_fixed.asm
     utils_wait_pin.asm
diff --git a/avr/common/utils_io.asm b/avr/common/utils_io.asm
new file mode 100644
index 0000000..8309a1e
--- /dev/null
+++ b/avr/common/utils_io.asm
@@ -0,0 +1,29 @@
+; ***************************************************************************
+; 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.   *
+; ***************************************************************************
+
+
+; M_IO_READ DEST, SRC
+.macro M_IO_READ
+.if @1 < 64
+  in @0, @1
+.else
+  lds @0, @1
+.endif
+.endmacro
+
+
+
+; M_IO_WRITE DEST, SRC
+.macro M_IO_WRITE
+.if @0 < 64
+  out @0, @1
+.else
+  sts @0, @1
+.endif
+.endmacro