diff --git a/avr/common/0BUILD b/avr/common/0BUILD
index bcc931c..dacfbb9 100644
--- a/avr/common/0BUILD
+++ b/avr/common/0BUILD
@@ -5,7 +5,9 @@
   <extradist>
     crc8.asm
     m_ringbuffer.asm
+    m_ringbuffer_y.asm
     ringbuffer.asm
+    ringbuffer_y.asm
     shared.asm
     utils.asm
     utils_copy_from_flash.asm
diff --git a/avr/common/m_ringbuffer.asm b/avr/common/m_ringbuffer.asm
index d189f9e..343925a 100644
--- a/avr/common/m_ringbuffer.asm
+++ b/avr/common/m_ringbuffer.asm
@@ -10,38 +10,36 @@
 
 
 ; ---------------------------------------------------------------------------
-; @macro m_ringbuffer_y_writebyte
+; @macro m_ringbuffer_writebyte
 ;
 ; @param R16 byte to write
-; @param Y   base address (for "LDD Y+nn" and "STD Y+nn")
 ; @param %0 constant maxBytes
-; @param %1 offset to Y to access usedBytes variable (for "LDD Y+nn" and "STD Y+nn")
-; @param %2 offset to Y to access readPos variable
-; @param %3 offset to Y to access writePos variable
-; @param %4 offset to Y to access buffer
+; @param %1 address of usedBytes variable
+; @param %2 address of readPos variable
+; @param %3 address of writePos variable
+; @param %4 address of buffer
 ; @return CFLAG set if okay, cleared on error (i.e. buffer full)
 ; @clobbers R17, X
 
-.macro m_ringbuffer_y_writebyte
-  ldd r17, Y+@1 ; usedBytes
-  cpi r17, @0   ; maxBytes
+.macro m_ringbuffer_writebyte
+  ld r17, @1       ; usedBytes
+  cpi r17, @0      ; maxBytes
   brcc l_end
   inc r17
-  std Y+@1, r17 ; usedBytes
-  ldd r17, Y+@3 ; writePos
-  mov xl, yl
-  mov xh, yh
-  adiw xh:xl, @4
+  st @1, r17       ; usedBytes
+  ld r17, @3       ; writePos
+  ldi xl, LOW(@4)  ; buffer start
+  ldi xh, HIGH(@4)
   add xl, r17
   adc xh, r17
   sub xh, r17
   st X, r16
   inc r17
-  cpi r17, @0
+  cpi r17, @0      ; maxBytes
   brcs l_store
   clr r17
 l_store:
-  std Y+@3, r17 ; writePos
+  st @3, r17    ; writePos
   sec
 l_end:
 .endmacro
@@ -50,29 +48,27 @@ l_end:
 
 
 ; ---------------------------------------------------------------------------
-; @macro m_ringbuffer_y_readbyte
+; @macro m_ringbuffer_readbyte
 ;
-; @param Y   base address (for "LDD Y+nn" and "STD Y+nn")
 ; @param %0 constant maxBytes
-; @param %1 offset to Y to access usedBytes variable (for "LDD Y+nn" and "STD Y+nn")
-; @param %2 offset to Y to access readPos variable
-; @param %3 offset to Y to access writePos variable
-; @param %4 offset to Y to access buffer
+; @param %1 address of usedBytes variable
+; @param %2 address of readPos variable
+; @param %3 address of writePos variable
+; @param %4 address of buffer
 ; @return CFLAG set if okay, cleared on error (i.e. buffer full)
 ; @return R16 byte read
 ; @clobbers R17, X
 
-.macro m_ringbuffer_y_readbyte
-  ldd r17, Y+@1 ; usedBytes
+.macro m_ringbuffer_readbyte
+  ld r17, @1       ; usedBytes
   tst r17
   clc
   breq l_end
   dec r17
-  std Y+@1, r17 ; usedBytes
-  ldd r17, Y+@2 ; readPos
-  mov xl, yl
-  mov xh, yh
-  adiw xh:xl, @4
+  st @1, r17       ; usedBytes
+  ld r17, @2       ; readPos
+  ldi xl, LOW(@4)  ; buffer start
+  ldi xh, HIGH(@4)
   add xl, r17
   adc xh, r17
   sub xh, r17
@@ -82,7 +78,7 @@ l_end:
   brcs l_store
   clr r17
 l_store:
-  std Y+@2, r17 ; readPos
+  st @2, r17       ; readPos
   sec
 l_end:
 .endmacro
@@ -90,21 +86,20 @@ l_end:
 
 
 ; ---------------------------------------------------------------------------
-; @macro m_ringbuffer_y_reset
+; @macro m_ringbuffer_reset
 ;
-; @param Y   base address (for "LDD Y+nn" and "STD Y+nn")
 ; @param %0 constant maxBytes
-; @param %1 offset to Y to access usedBytes variable (for "LDD Y+nn" and "STD Y+nn")
-; @param %2 offset to Y to access readPos variable
-; @param %3 offset to Y to access writePos variable
-; @param %4 offset to Y to access buffer
+; @param %1 address of usedBytes variable
+; @param %2 address of readPos variable
+; @param %3 address of writePos variable
+; @param %4 address of buffer
 ; @clobbers R17
 
-.macro m_ringbuffer_y_reset
+.macro m_ringbuffer_reset
   clr r17
-  std Y+@1, r17 ; usedBytes
-  std Y+@2, r17 ; readPos
-  std Y+@3, r17 ; writePos
+  st @1, r17 ; usedBytes
+  st @2, r17 ; readPos
+  st @3, r17 ; writePos
 l_end:
 .endmacro
 ; @end
diff --git a/avr/common/m_ringbuffer_y.asm b/avr/common/m_ringbuffer_y.asm
new file mode 100644
index 0000000..7a8fa1d
--- /dev/null
+++ b/avr/common/m_ringbuffer_y.asm
@@ -0,0 +1,117 @@
+; ***************************************************************************
+; copyright   : (C) 2025 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.   *
+; ***************************************************************************
+
+
+
+; ---------------------------------------------------------------------------
+; @macro m_ringbuffer_y_writebyte
+;
+; @param R16 byte to write
+; @param Y   base address (for "LDD Y+nn" and "STD Y+nn")
+; @param %0 offset to Y to access maxBytes variable (for "LDD Y+nn" and "STD Y+nn")
+; @param %1 offset to Y to access usedBytes
+; @param %2 offset to Y to access readPos variable
+; @param %3 offset to Y to access writePos variable
+; @param %4 offset to Y to access buffer
+; @return CFLAG set if okay, cleared on error (i.e. buffer full)
+; @clobbers R17, R18, X
+
+.macro m_ringbuffer_y_writebyte
+  ldd r18, Y+@0 ; maxBytes
+  ldd r17, Y+@1 ; usedBytes
+  cp r17, r18
+  brcc l_end    ; out-of-range
+  inc r17
+  std Y+@1, r17 ; usedBytes
+  ldd r17, Y+@3 ; writePos
+  mov xl, yl
+  mov xh, yh
+  adiw xh:xl, @4
+  add xl, r17
+  adc xh, r17
+  sub xh, r17
+  st X, r16
+  inc r17
+  cp r17, r18
+  brcs l_store
+  clr r17
+l_store:
+  std Y+@3, r17 ; writePos
+  sec
+l_end:
+.endmacro
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @macro m_ringbuffer_y_readbyte
+;
+; @param Y   base address (for "LDD Y+nn" and "STD Y+nn")
+; @param %0 offset to Y to access maxBytes variable (for "LDD Y+nn" and "STD Y+nn")
+; @param %1 offset to Y to access usedBytes
+; @param %2 offset to Y to access readPos variable
+; @param %3 offset to Y to access writePos variable
+; @param %4 offset to Y to access buffer
+; @return CFLAG set if okay, cleared on error (i.e. buffer full)
+; @return R16 byte read
+; @clobbers R17, R18, X
+
+.macro m_ringbuffer_y_readbyte
+  ldd r18, Y+@0 ; maxBytes
+  ldd r17, Y+@1 ; usedBytes
+  tst r17
+  clc
+  breq l_end
+  dec r17
+  std Y+@1, r17 ; usedBytes
+  ldd r17, Y+@2 ; readPos
+  mov xl, yl
+  mov xh, yh
+  adiw xh:xl, @4
+  add xl, r17
+  adc xh, r17
+  sub xh, r17
+  ld r16, X
+  inc r17
+  cp r17, r18
+  brcs l_store
+  clr r17       ; wrap-around
+l_store:
+  std Y+@2, r17 ; readPos
+  sec
+l_end:
+.endmacro
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @macro m_ringbuffer_y_reset
+;
+; @param Y   base address (for "LDD Y+nn" and "STD Y+nn")
+; @param %0 offset to Y to access maxBytes variable (for "LDD Y+nn" and "STD Y+nn")
+; @param %1 offset to Y to access usedBytes
+; @param %2 offset to Y to access readPos variable
+; @param %3 offset to Y to access writePos variable
+; @param %4 offset to Y to access buffer
+; @clobbers R17
+
+.macro m_ringbuffer_y_reset
+  clr r17
+  std Y+@1, r17 ; usedBytes
+  std Y+@2, r17 ; readPos
+  std Y+@3, r17 ; writePos
+l_end:
+.endmacro
+; @end
+
+
+
+
diff --git a/avr/common/ringbuffer_y.asm b/avr/common/ringbuffer_y.asm
new file mode 100644
index 0000000..ac56ddc
--- /dev/null
+++ b/avr/common/ringbuffer_y.asm
@@ -0,0 +1,91 @@
+; ***************************************************************************
+; copyright   : (C) 2025 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.   *
+; ***************************************************************************
+
+
+.equ RINGBUFFERY_OFFS_MAXSIZE  = 0
+.equ RINGBUFFERY_OFFS_USED     = 1
+.equ RINGBUFFERY_OFFS_READPOS  = 2
+.equ RINGBUFFERY_OFFS_WRITEPOS = 3
+.equ RINGBUFFERY_OFFS_DATA     = 4
+
+
+
+; ---------------------------------------------------------------------------
+; @routine RingBufferY_Init
+;
+; @param R16 size of ringbuffer
+; @param Y   base address of ringbuffer struct
+; @return CFLAG set if okay, cleared on error (i.e. buffer full)
+; @clobbers R17
+
+RingBufferY_Init:
+  std Y+RINGBUFFERY_OFFS_MAXSIZE, r16
+  rjmp RingBufferY_Reset
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine RingBufferY_WriteByte
+;
+; @param R16 byte to write
+; @param Y   base address of ringbuffer struct
+; @return CFLAG set if okay, cleared on error (i.e. buffer full)
+; @clobbers R17, R18, X
+
+RingBufferY_WriteByte:
+  m_ringbuffer_y_writebyte \
+    RINGBUFFERY_OFFS_MAXSIZE, \
+    RINGBUFFERY_OFFS_USED, \
+    RINGBUFFERY_OFFS_READPOS, \
+    RINGBUFFERY_OFFS_WRITEPOS, \
+    RINGBUFFERY_OFFS_DATA
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @macro m_ringbuffer_y_readbyte
+;
+; @param Y   base address of ringbuffer struct
+; @return CFLAG set if okay, cleared on error (i.e. buffer empty)
+; @return R16 byte read
+; @clobbers R17, R18, X
+
+RingBufferY_ReadByte:
+  m_ringbuffer_y_readbyte \
+    RINGBUFFERY_OFFS_MAXSIZE, \
+    RINGBUFFERY_OFFS_USED, \
+    RINGBUFFERY_OFFS_READPOS, \
+    RINGBUFFERY_OFFS_WRITEPOS, \
+    RINGBUFFERY_OFFS_DATA
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @macro m_ringbuffer_y_reset
+;
+; @param Y   base address of ringbuffer struct
+; @clobbers R17
+
+RingBufferY_Reset:
+  m_ringbuffer_y_reset \
+    RINGBUFFERY_OFFS_MAXSIZE, \
+    RINGBUFFERY_OFFS_USED, \
+    RINGBUFFERY_OFFS_READPOS, \
+    RINGBUFFERY_OFFS_WRITEPOS, \
+    RINGBUFFERY_OFFS_DATA
+  ret
+; @end
+
+
+