diff --git a/avr/modules/f_keepup/0BUILD b/avr/modules/f_keepup/0BUILD
new file mode 100644
index 0000000..febd367
--- /dev/null
+++ b/avr/modules/f_keepup/0BUILD
@@ -0,0 +1,11 @@
+<?xml?>
+
+<gwbuild>
+
+  <extradist>
+    main.asm
+  </extradist>
+
+</gwbuild>
+
+
diff --git a/avr/modules/f_keepup/main.asm b/avr/modules/f_keepup/main.asm
new file mode 100644
index 0000000..7f24efd
--- /dev/null
+++ b/avr/modules/f_keepup/main.asm
@@ -0,0 +1,107 @@
+; ***************************************************************************
+; 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.   *
+; ***************************************************************************
+
+
+; ***************************************************************************
+; defines
+
+.equ FILTER_KEEPUP_OFFS_TIMER           = 0
+.equ FILTER_KEEPUP_OFFS_RESTARTVALUE    = 1
+.equ FILTER_KEEPUP_DATA_SIZE            = 2
+
+
+
+; ***************************************************************************
+; code
+
+.cseg
+
+
+
+; ---------------------------------------------------------------------------
+; @routine FilterKeepUp_Init @global
+;
+; @param Y  pointer to filter data
+; @clobbers r16
+
+FilterKeepUp_Init:
+  clr r16
+  std Y+FILTER_KEEPUP_OFFS_TIMER, r16
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine FilterKeepUp_Fini @global
+;
+; @param Y  pointer to filter data
+
+FilterKeepUp_Fini:
+  ; nothing to do
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine FilterKeepUp_GetValue @global
+;
+; @param Y  pointer to filter data
+; @return R16 value
+; @clobbers none
+
+FilterKeepUp_GetValue:
+  ldd r16, Y+FILTER_KEEPUP_OFFS_TIMER
+  tst r16
+  breq FilterKeepUp_GetValue_end
+  ldi r16, 1
+FilterKeepUp_GetValue_end:
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine FilterKeepUp_SetValue @global
+;
+; @param Y  pointer to filter data
+; @param R16 value
+; @clobbers r17
+
+FilterKeepUp_SetValue:
+  tst r16
+  breq FilterKeepUp_SetValue_end
+  ldd r17, Y+FILTER_KEEPUP_OFFS_RESTARTVALUE
+  std Y+FILTER_KEEPUP_OFFS_TIMER, r17
+FilterKeepUp_SetValue_end:
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine FilterKeepUp_Every100ms @global
+;
+; @param Y  pointer to filter data
+; @clobbers r16
+
+FilterKeepUp_Every100ms:
+  ldd r16, Y+FILTER_KEEPUP_OFFS_TIMER
+  tst r16
+  breq FilterKeepUp_Every100ms_end
+  dec r16
+  std Y+FILTER_KEEPUP_OFFS_TIMER, r16
+FilterKeepUp_Every100ms_end:
+  ret
+; @end
+
+
+
+
diff --git a/avr/modules/f_stabilize/0BUILD b/avr/modules/f_stabilize/0BUILD
new file mode 100644
index 0000000..febd367
--- /dev/null
+++ b/avr/modules/f_stabilize/0BUILD
@@ -0,0 +1,11 @@
+<?xml?>
+
+<gwbuild>
+
+  <extradist>
+    main.asm
+  </extradist>
+
+</gwbuild>
+
+
diff --git a/avr/modules/f_stabilize/main.asm b/avr/modules/f_stabilize/main.asm
new file mode 100644
index 0000000..36bd396
--- /dev/null
+++ b/avr/modules/f_stabilize/main.asm
@@ -0,0 +1,194 @@
+; ***************************************************************************
+; 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.   *
+; ***************************************************************************
+
+
+; ***************************************************************************
+; defines
+
+.equ FILTER_STABILIZE_OFFS_STATUSBYTE        = 0
+.equ FILTER_STABILIZE_OFFS_TIMER             = 1
+.equ FILTER_STABILIZE_OFFS_COUNTER           = 2
+.equ FILTER_STABILIZE_OFFS_STABLECOUNTVAL    = 3
+.equ FILTER_STABILIZE_DATA_SIZE              = 4
+
+.equ FILTER_STABILIZE_STATUS_LASTVALUE_BIT   = 0
+.equ FILTER_STABILIZE_STATUS_STABLEVALUE_BIT = 1
+.equ FILTER_STABILIZE_STATUS_REPORT0_BIT     = 4
+.equ FILTER_STABILIZE_STATUS_REPORT1_BIT     = 5
+.equ FILTER_STABILIZE_STATUS_REPEAT0_BIT     = 6
+.equ FILTER_STABILIZE_STATUS_REPEAT1_BIT     = 7
+
+.equ FILTER_STABILIZE_REPORTTIME1            = 1   ; report after 100ms
+.equ FILTER_STABILIZE_REPORTTIME2            = 11  ; report after 1100ms
+.equ FILTER_STABILIZE_REPORTTIME3            = 22  ; report after 2200ms
+.equ FILTER_STABILIZE_REPEATTIME             = 200 ; 20s
+
+
+
+; ***************************************************************************
+; code
+
+.cseg
+
+
+; ---------------------------------------------------------------------------
+; @routine FilterStabilize_Init @global
+;
+; @param Y  pointer to filter data
+
+FilterStabilize_Init:
+  clr r16
+  std Y+FILTER_STABILIZE_OFFS_COUNTER, r16
+  std Y+FILTER_STABILIZE_OFFS_STATUSBYTE, r16
+  dec r16
+  std Y+FILTER_STABILIZE_OFFS_TIMER, r16  ; hold timer
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine FilterStabilize_Fini @global
+;
+; @param Y  pointer to filter data
+
+FilterStabilize_Fini:
+  ; nothing to do
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine FilterStabilize_GetValue @global
+;
+; Values are reduced to 1 bit (i.e. either "0" or "1").
+;
+; @param Y  pointer to filter data
+; @return R19:R18 value
+
+FilterStabilize_GetValue:
+  ldd r18, Y+FILTER_STABILIZE_OFFS_STATUSBYTE
+  lsr r18, FILTER_STABILIZE_STATUS_STABLEVALUE_BIT
+  andi r18, 1
+  clr r19
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine FilterStabilize_SetValue @global
+;
+; The stored value is reduced to 1 bit (i.e. either "0" or "1").
+;
+; @param Y  pointer to filter data
+; @param R19:R18 value
+; @clobbers r16, r17
+
+FilterStabilize_SetValue:
+  mov r16, r18
+  or r16, r19
+  breq FilterStabilize_SetValue_set
+  ldi r16, (1<<FILTER_STABILIZE_STATUS_LASTVALUE_BIT)
+FilterStabilize_SetValue_set:
+  ldd r17, Y+FILTER_STABILIZE_OFFS_STATUSBYTE
+  eor r17, r16
+  andi r17, FILTER_STABILIZE_STATUS_LASTVALUE_BIT
+  breq FilterStabilize_SetValue_noChange            ; no change
+  ; changed
+  ldd r16, Y+FILTER_STABILIZE_OFFS_STATUSBYTE
+  eor r16, r17                                      ; change lastValue bit in status byte
+  std Y+FILTER_STABILIZE_OFFS_STATUSBYTE, r16
+  clr r16                                           ; reset counter
+  std Y+FILTER_STABILIZE_OFFS_COUNTER, r16
+  dec r16
+  std Y+FILTER_STABILIZE_OFFS_TIMER, r16            ; timer=255 (hold timer)
+  rjmp FilterStabilize_SetValue_end
+FilterStabilize_SetValue_noChange:
+  ldd r16, Y+FILTER_STABILIZE_OFFS_COUNTER
+  inc r16
+  breq FilterStabilize_SetValue_end                 ; stop counter at 255
+  std Y+FILTER_STABILIZE_OFFS_COUNTER, r16
+  ldd r17, Y+FILTER_STABILIZE_OFFS_STABLECOUNTVAL
+  cpi r16, r17
+  brne FilterStabilize_SetValue_end
+  ; copy last value to stable value
+  ldd r16, Y+FILTER_STABILIZE_OFFS_STATUSBYTE
+  mov r17, r16
+  lsl r17, (FILTER_STABILIZE_STATUS_STABLEVALUE_BIT-FILTER_STABILIZE_STATUS_LASTVALUE_BIT) ; r17=new value
+  andi r17, (1<<FILTER_STABILIZE_STATUS_STABLEVALUE_BIT)  ; isolate new stable bit
+  andi r16, ~(1<<FILTER_STABILIZE_STATUS_STABLEVALUE_BIT) ; clear stable bit
+  or r16, r17                                             ; or-in new stable bit
+  std Y+FILTER_STABILIZE_OFFS_STATUSBYTE, r16
+  ; start timer
+  clr r16
+  std Y+FILTER_STABILIZE_OFFS_TIMER, r16
+FilterStabilize_SetValue_end:
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine FilterStabilize_Every100ms @global
+;
+; @return CFLAG set if value should be reported, cleared otherwise
+; @param  Y     pointer to filter data
+; @clobbers r16, r18, r19
+
+FilterStabilize_Every100ms:
+  ldd r16, Y+FILTER_STABILIZE_OFFS_TIMER
+  inc r16
+  breq FilterStabilize_Every100ms_clcRet            ; hold counter at 255
+  std Y+FILTER_STABILIZE_OFFS_TIMER, r16
+  cpi r16, FILTER_STABILIZE_REPEATTIME
+  breq FilterStabilize_Every100ms_repeat
+  cpi r16, FILTER_STABILIZE_REPORTTIME1
+  breq FilterStabilize_Every100ms_report
+  cpi r16, FILTER_STABILIZE_REPORTTIME2
+  breq FilterStabilize_Every100ms_report
+  cpi r16, FILTER_STABILIZE_REPORTTIME3
+  breq FilterStabilize_Every100ms_report
+  rjmp FilterStabilize_Every100ms_clcRet
+FilterStabilize_Every100ms_report:
+  ldd r18, Y+FILTER_STABILIZE_OFFS_STATUSBYTE
+  sbrc r18, FILTER_STABILIZE_STATUS_STABLEVALUE_BIT
+    rjmp FilterStabilize_Every100ms_report1
+FilterStabilize_Every100ms_report0:                 ; value is 0
+  sbrs r18, FILTER_STABILIZE_STATUS_REPORT0_BIT
+    rjmp FilterStabilize_Every100ms_clcRet          ; REPORT0 not set
+  rjmp FilterStabilize_Every100ms_secRet
+FilterStabilize_Every100ms_report1:                 ; value is 1
+  sbrs r18, FILTER_STABILIZE_STATUS_REPORT1_BIT
+    rjmp FilterStabilize_Every100ms_clcRet          ; REPORT1 not set
+  rjmp FilterStabilize_Every100ms_secRet
+FilterStabilize_Every100ms_repeat:
+  ldd r18, Y+FILTER_STABILIZE_OFFS_STATUSBYTE
+  sbrc r18, FILTER_STABILIZE_STATUS_STABLEVALUE_BIT
+    rjmp FilterStabilize_Every100ms_repeat1
+FilterStabilize_Every100ms_repeat0:                 ; value is 0
+  sbrs r18, FILTER_STABILIZE_STATUS_REPEAT0_BIT
+    rjmp FilterStabilize_Every100ms_clcRet          ; REPEAT0 not set
+  rjmp FilterStabilize_Every100ms_resetTimer
+FilterStabilize_Every100ms_repeat1:                 ; value is 1
+  sbrs r18, FILTER_STABILIZE_STATUS_REPEAT1_BIT
+    rjmp FilterStabilize_Every100ms_clcRet          ; REPEAT1 not set
+FilterStabilize_Every100ms_resetTimer:
+  clr r16
+  std Y+FILTER_STABILIZE_OFFS_TIMER, r16
+FilterStabilize_Every100ms_clcRet:
+  clc
+  ret
+FilterStabilize_Every100ms_secRet:
+  sec
+  ret
+; @end
+
+