diff --git a/avr/0BUILD b/avr/0BUILD
index 5efda71..9a7c418 100644
--- a/avr/0BUILD
+++ b/avr/0BUILD
@@ -36,6 +36,22 @@
 
 
   </target>
+
+  <target type="AvrHexFile" name="att84_base" >
+
+    <includes type="avrasm" >
+      -I $(builddir)
+      -I $(srcdir)
+      -I $(topsrcdir)/avr
+    </includes>
+
+
+    <sources type="avrasm" >
+      att84_base.asm
+    </sources>
+
+
+  </target>
   
 </gwbuild>
 
diff --git a/avr/att84_base.asm b/avr/att84_base.asm
index 9bce9f6..dc1382b 100644
--- a/avr/att84_base.asm
+++ b/avr/att84_base.asm
@@ -1,7 +1,7 @@
 ; ***************************************************************************
-; Source file for temperature sensor node on AtTiny 84
+; Source file for base system node on AtTiny 84
 ;
-; This is for the full system (i.e. not the boot loader).
+; This is for the maintenance system (i.e. the flash loader).
 ;
 ; All definitions and changes should go into this file.
 ;
@@ -11,10 +11,10 @@
 ;                            VCC  1     14  GND
 ;                            PB0  2     13  PA0
 ;                            PB1  3     12  PA1  COM-DATA
-;                  /RESET    PB3  4     11  PA2  OWI
+;                  /RESET    PB3  4     11  PA2
 ;                  KEY1      PB2  5     10  PA3  LED
-;                  COM_ATTN  PA7  6      9  PA4  TWI-SCL
-;                  TWI-SDA   PA6  7      8  PA5
+;                  COM_ATTN  PA7  6      9  PA4
+;                            PA6  7      8  PA5
 ;                                 --------
 ;
 ; ***************************************************************************
@@ -42,17 +42,24 @@
 ; ---------------------------------------------------------------------------
 ; list of modules to use
 
+#define BASE_SYSTEM
+#define WITH_FLASH
+
 #define MODULES_TIMER
 #define MODULES_COM
-#define MODULES_LED
-#define MODULES_TWI_MASTER
-#define MODULES_LCD
-#define MODULES_SI7021
+;#define MODULES_LED
+; #define MODULES_TWI_MASTER
+; #define MODULES_LCD
+; #define MODULES_SI7021
 
 
-.equ VALUE_ID_TEMP1 = 0x01
-.equ VALUE_ID_HUM1  = 0x02
 
+; ---------------------------------------------------------------------------
+; EEPROM positions
+
+
+.equ EEPROM_OFFS_UUID    = 0    ; 4 bytes (occupy total of 8 bytes for extensibility)
+.equ EEPROM_OFFS_COMADDR = 8    ; 1 byte
 
 
 ; ---------------------------------------------------------------------------
@@ -80,8 +87,6 @@
 ; ---------------------------------------------------------------------------
 ; TWI master module
 
-.equ LCD_TWI_ADDRESS      = 0x3c
-
 .equ TWI_DDR_SCL          = DDRA
 .equ TWI_PORT_SCL         = PORTA
 .equ TWI_PIN_SCL          = PINA
@@ -94,6 +99,29 @@
 
 
 
+; ---------------------------------------------------------------------------
+; LCD module
+
+.equ LCD_TWI_ADDRESS      = 0x3c
+
+
+
+; ---------------------------------------------------------------------------
+; BMP 280
+
+.equ BMP280_ADDR          = 0x76
+
+
+
+; ---------------------------------------------------------------------------
+; SI 7021
+
+.equ SI7021_ADDR          = 0x40
+
+
+
+
+
 ; ***************************************************************************
 ; code segment
 
@@ -104,58 +132,47 @@
 
 ; ---------------------------------------------------------------------------
 ; Reset and interrupt vectors
+  rjmp PC+0x20 ; Reset vector
+  rjmp PC+0x20 ; EXT_INT0
+  rjmp PC+0x20 ; PCI0
+  rjmp PC+0x20 ; PCI1
+  rjmp PC+0x20 ; WATCHDOG
+  rjmp PC+0x20 ; ICP1
+  rjmp PC+0x20 ; OC1A
+  rjmp PC+0x20 ; OC1B
+  rjmp PC+0x20 ; OVF1
+  rjmp PC+0x20 ; OC0A
+  rjmp PC+0x20 ; OC0B
+  rjmp PC+0x20 ; OVF0
+  rjmp PC+0x20 ; ACI
+  rjmp PC+0x20 ; ADCC
+  rjmp PC+0x20 ; ERDY
+  rjmp PC+0x20 ; USI_STR
+  rjmp PC+0x20 ; USI_OVF
 
-	rjmp main ; Reset vector
-	reti ; EXT_INT0
-	rjmp comIsrPcint0 ; PCI0
-	reti ; PCI1
-	reti ; WATCHDOG
-	reti ; ICP1
-	reti ; OC1A
-	reti ; OC1B
-	reti ; OVF1
-        rjmp timerIrqOC0A ; OC0A
-	reti ; OC0B
-	reti ; OVF0
-	reti ; ACI
-	reti ; ADCC
-	reti ; ERDY
-	reti ; USI_STR
-	reti ; USI_OVF
-
-.org 0x40
-; ---------------------------------------------------------------------------
-; Node Id (not overwritten when updating system)
-
-nodeUid: .db 0, 0, 0, 0, 0, 0, 0, 0
-
-
-
-
-.org 0x50 ; begin of maintenance system
 
 ; ---------------------------------------------------------------------------
-; Reset and interrupt vectors of maintenance system
+; maintenance system starts here.
 
-maintIrqHandlerTable:
-        .dw main  ; reset address
-        .dw 0     ; EXT_INT0
-	.dw comIsrPcint0 ; PCI0
-	.dw 0 ; PCI1
-	.dw 0 ; WATCHDOG
-	.dw 0 ; ICP1
-	.dw 0 ; OC1A
-	.dw 0 ; OC1B
-	.dw 0 ; OVF1
-        .dw timerIrqOC0A ; OC0A
-	.dw 0 ; OC0B
-	.dw 0 ; OVF0
-	.dw 0 ; ACI
-	.dw 0 ; ADCC
-	.dw 0 ; ERDY
-	.dw 0 ; USI_STR
-	.dw 0 ; USI_OVF
+.org 0x20
 
+  rjmp main ; Reset vector
+  reti ; EXT_INT0
+  rjmp comIsrPcint0 ; PCI0
+  reti ; PCI1
+  reti ; WATCHDOG
+  reti ; ICP1
+  reti ; OC1A
+  reti ; OC1B
+  reti ; OVF1
+  rjmp timerIrqOC0A ; OC0A
+  reti ; OC0B
+  reti ; OVF0
+  reti ; ACI
+  reti ; ADCC
+  reti ; ERDY
+  reti ; USI_STR
+  reti ; USI_OVF
 
 
 ; ***************************************************************************
@@ -163,13 +180,9 @@ maintIrqHandlerTable:
 
 .include "utils.asm"
 .include "timer.asm"
-.include "led.asm"
 .include "com.asm"
 .include "comproto.asm"
-;.include "twimaster.asm"
-;.include "lcd.asm"
-;.include "bmp280.asm"
-;.include "si7021.asm"
+.include "flash.asm"
 
 
 
@@ -178,19 +191,12 @@ maintIrqHandlerTable:
 
 .dseg
 
-ledA3Sram:   .byte LED_SRAM_SIZE
-
-
-
 
 ; ***************************************************************************
 ; data in FLASH
 
 .cseg
 
-ledA3Flash:    .db DDRA+0x20, PORTA+0x20, PINA+0x20, (1<<PORTA3)
-blinkPattern:  .db 5, 5, 5, 5, 5, 10, 0xff, 0xff   ; 3 short blinks, 1s pause, restart
-blinkPattern2: .db 10, 20, 0xff, 0xff   ; 1 long blink, 2s pause, restart
 
 
 
@@ -199,58 +205,36 @@ blinkPattern2: .db 10, 20, 0xff, 0xff   ; 1 long blink, 2s pause, restart
 
 
 ; ---------------------------------------------------------------------------
-; onEvery100ms
-;
-; Called every 100ms. Add your routine calls here.
-;
-; IN:
-; - nothing
-; OUT:
-; - nothing
-; USED: depending on called routines
+; Called on first time run, i.e. on system start. No arguments, no results.
+
+onSystemStart:
+  rcall Utils_SetupUid
+  ldi r16, COM_MAINTENANCE_ADDR ; use fixed address in base system, smaller code
+  sts comAddress, r16
+;  rcall CPRO_StartReclaimAddrProcedure
+  ret
+
+
+
+; ---------------------------------------------------------------------------
+; Called every 100ms. Add your routine calls here. No arguments, no results.
 
 onEvery100ms:
-#ifdef MODULES_LED
-  ; ticker for LED module
-  ldi zl, LOW(ledA3Flash)
-  ldi zh, HIGH(ledA3Flash)
-  ldi yl, LOW(ledA3Sram)
-  ldi yh, HIGH(ledA3Sram)
-  rcall Led_Tick
-#endif
-
-  ; add more calls here
-  
   ret
 
 
 
 ; ---------------------------------------------------------------------------
-; onEverySecond
-;
-; Called every second. Add your routine calls here.
-;
-; IN:
-; - nothing
-; OUT:
-; - nothing
-; USED: depending on called routines
+; Called every second. Add your routine calls here. No arguments, no results.
 
 onEverySecond:
+  rcall CPRO_OnEverySecond
   ret
 
 
 
 ; ---------------------------------------------------------------------------
-; onEvery10s
-;
-; Called every 10 seconds. Add your routine calls here.
-;
-; IN:
-; - nothing
-; OUT:
-; - nothing
-; USED: depending on called routines
+; Called every 10 seconds. Add your routine calls here.  No arguments, no results.
 
 onEvery10s:
   ret
@@ -258,15 +242,7 @@ onEvery10s:
 
 
 ; ---------------------------------------------------------------------------
-; onEvery30s
-;
-; Called every 10 seconds. Add your routine calls here.
-;
-; IN:
-; - nothing
-; OUT:
-; - nothing
-; USED: depending on called routines
+; Called every 30 seconds. Add your routine calls here. No arguments, no results.
 
 onEvery30s:
   ret
@@ -274,24 +250,49 @@ onEvery30s:
 
 
 ; ---------------------------------------------------------------------------
-; onEveryMinute
-;
-; Called every minute. Add your routine calls here.
-;
-; IN:
-; - nothing
-; OUT:
-; - nothing
-; USED: depending on called routines
+; Called every minute. Add your routine calls here. No arguments, no results.
 
 onEveryMinute:
-  in r15, SREG ; debug
-  cli
-  push r15
-    ldi r16, 219
-    rcall CPRO_EnqueueComSendStats
-  pop r15
-  out SREG, r15
+  ret
+
+
+
+; ---------------------------------------------------------------------------
+; Called every 15 minutes. Add your routine calls here. No arguments, no results.
+
+onEvery15m:
+  ret
+
+
+
+; ---------------------------------------------------------------------------
+; Called every 30 minutes. Add your routine calls here. No arguments, no results.
+
+onEvery30m:
+  ret
+
+
+
+; ---------------------------------------------------------------------------
+; Called every hour. Add your routine calls here. No arguments, no results.
+
+onEvery1h:
+  ret
+
+
+
+; ---------------------------------------------------------------------------
+; Called every 12 hours. Add your routine calls here. No arguments, no results.
+
+onEvery12h:
+  ret
+
+
+
+; ---------------------------------------------------------------------------
+; Called every day. Add your routine calls here. No arguments, no results.
+
+onEvery1d:
   ret
 
 
@@ -309,7 +310,7 @@ onEveryMinute:
 ; USED: depending on called routines
 
 onPacketReceived:
-  clc               ; not handled
+  rcall CPRO_OnPacketReceived
   ret
 
 
diff --git a/avr/att84_temp1.asm b/avr/att84_temp1.asm
index 562bc69..b9f15ac 100644
--- a/avr/att84_temp1.asm
+++ b/avr/att84_temp1.asm
@@ -49,6 +49,8 @@
 #define MODULES_LCD
 #define MODULES_SI7021
 
+#define LCD_MINIMAL_FONT
+
 
 .equ VALUE_ID_TEMP1 = 0x01
 .equ VALUE_ID_HUM1  = 0x02
@@ -132,37 +134,33 @@
 
 
 ; ---------------------------------------------------------------------------
-; Reset and interrupt vectors
-
-	rjmp main ; Reset vector
-	reti ; EXT_INT0
-	rjmp comIsrPcint0 ; PCI0
-	reti ; PCI1
-	reti ; WATCHDOG
-	reti ; ICP1
-	reti ; OC1A
-	reti ; OC1B
-	reti ; OVF1
-        rjmp timerIrqOC0A ; OC0A
-	reti ; OC0B
-	reti ; OVF0
-	reti ; ACI
-	reti ; ADCC
-	reti ; ERDY
-	reti ; USI_STR
-	reti ; USI_OVF
-
-
+; Reset and interrupt vectors (will be removed as soon as we can flash data over COM)
 
+	rjmp PC+0x500 ; Reset vector
+	rjmp PC+0x500 ; EXT_INT0
+	rjmp PC+0x500 ; PCI0
+	rjmp PC+0x500 ; PCI1
+	rjmp PC+0x500 ; WATCHDOG
+        rjmp PC+0x500 ; ICP1
+        rjmp PC+0x500 ; OC1A
+	rjmp PC+0x500 ; OC1B
+	rjmp PC+0x500 ; OVF1
+        rjmp PC+0x500 ; OC0A
+	rjmp PC+0x500 ; OC0B
+	rjmp PC+0x500 ; OVF0
+	rjmp PC+0x500 ; ACI
+	rjmp PC+0x500 ; ADCC
+	rjmp PC+0x500 ; ERDY
+	rjmp PC+0x500 ; USI_STR
+	rjmp PC+0x500 ; USI_OVF
 
 
 ; ---------------------------------------------------------------------------
-; maintenance system starts here.
+; working system starts here.
 
-.org 0x50
+.org 0x0500
 
 
-realInterruptTable:
 	rjmp main ; Reset vector
 	reti ; EXT_INT0
 	rjmp comIsrPcint0 ; PCI0
@@ -193,7 +191,6 @@ realInterruptTable:
 .include "comproto_addr.asm"
 .include "twimaster.asm"
 .include "lcd.asm"
-;.include "bmp280.asm"
 .include "si7021.asm"
 
 
@@ -208,14 +205,6 @@ ledA3Sram:   .byte LED_SRAM_SIZE
 
 
 
-; ***************************************************************************
-; data in EEPROM
-
-.eseg
-
-
-
-
 ; ***************************************************************************
 ; data in FLASH
 
@@ -223,7 +212,7 @@ ledA3Sram:   .byte LED_SRAM_SIZE
 
 ledA3Flash:    .db DDRA+0x20, PORTA+0x20, PINA+0x20, (1<<PORTA3)
 blinkPattern:  .db 5, 5, 5, 5, 5, 10, 0xff, 0xff   ; 3 short blinks, 1s pause, restart
-blinkPattern2: .db 10, 20, 0xff, 0xff   ; 1 long blink, 2s pause, restart
+;blinkPattern2: .db 10, 20, 0xff, 0xff   ; 1 long blink, 2s pause, restart
 
 
 .include "main.asm"
@@ -231,15 +220,7 @@ blinkPattern2: .db 10, 20, 0xff, 0xff   ; 1 long blink, 2s pause, restart
 
 
 ; ---------------------------------------------------------------------------
-; onSystemStart
-;
-; Called on first time run, i.e. on system start.
-;
-; IN:
-; - nothing
-; OUT:
-; - nothing
-; USED: depending on called routines
+; Called on first time run, i.e. on system start. No arguments, no results.
 
 onSystemStart:
   rcall Utils_SetupUid
@@ -253,15 +234,7 @@ onSystemStart:
 
 
 ; ---------------------------------------------------------------------------
-; onEvery100ms
-;
-; Called every 100ms. Add your routine calls here.
-;
-; IN:
-; - nothing
-; OUT:
-; - nothing
-; USED: depending on called routines
+; Called every 100ms. Add your routine calls here. No arguments, no results.
 
 onEvery100ms:
 #ifdef MODULES_LED
@@ -272,23 +245,12 @@ onEvery100ms:
   ldi yh, HIGH(ledA3Sram)
   rcall Led_Tick
 #endif
-
-  ; add more calls here
-  
   ret
 
 
 
 ; ---------------------------------------------------------------------------
-; onEverySecond
-;
-; Called every second. Add your routine calls here.
-;
-; IN:
-; - nothing
-; OUT:
-; - nothing
-; USED: depending on called routines
+; Called every second. Add your routine calls here. No arguments, no results.
 
 onEverySecond:
 ;  rcall TWI_Master_ScanNext
@@ -298,15 +260,7 @@ onEverySecond:
 
 
 ; ---------------------------------------------------------------------------
-; onEvery10s
-;
-; Called every 10 seconds. Add your routine calls here.
-;
-; IN:
-; - nothing
-; OUT:
-; - nothing
-; USED: depending on called routines
+; Called every 10 seconds. Add your routine calls here.  No arguments, no results.
 
 onEvery10s:
   rcall printSendStats
@@ -315,15 +269,7 @@ onEvery10s:
 
 
 ; ---------------------------------------------------------------------------
-; onEvery30s
-;
-; Called every 10 seconds. Add your routine calls here.
-;
-; IN:
-; - nothing
-; OUT:
-; - nothing
-; USED: depending on called routines
+; Called every 30 seconds. Add your routine calls here. No arguments, no results.
 
 onEvery30s:
 #ifdef MODULES_SI7021
@@ -340,15 +286,7 @@ onEvery30s:
 
 
 ; ---------------------------------------------------------------------------
-; onEveryMinute
-;
-; Called every minute. Add your routine calls here.
-;
-; IN:
-; - nothing
-; OUT:
-; - nothing
-; USED: depending on called routines
+; Called every minute. Add your routine calls here. No arguments, no results.
 
 onEveryMinute:
 #ifdef MODULES_COM
@@ -364,6 +302,46 @@ onEveryMinute_l1:
 
 
 
+; ---------------------------------------------------------------------------
+; Called every 15 minutes. Add your routine calls here. No arguments, no results.
+
+onEvery15m:
+  ret
+
+
+
+; ---------------------------------------------------------------------------
+; Called every 30 minutes. Add your routine calls here. No arguments, no results.
+
+onEvery30m:
+  ret
+
+
+
+; ---------------------------------------------------------------------------
+; Called every hour. Add your routine calls here. No arguments, no results.
+
+onEvery1h:
+  ret
+
+
+
+; ---------------------------------------------------------------------------
+; Called every 12 hours. Add your routine calls here. No arguments, no results.
+
+onEvery12h:
+  ret
+
+
+
+; ---------------------------------------------------------------------------
+; Called every day. Add your routine calls here. No arguments, no results.
+
+onEvery1d:
+  ret
+
+
+
 ; ---------------------------------------------------------------------------
 ; onPacketReceived:
 ;
diff --git a/avr/com.asm b/avr/com.asm
index 441d0bc..2686c4b 100644
--- a/avr/com.asm
+++ b/avr/com.asm
@@ -6,6 +6,7 @@
 
 .equ COM_MAXWAIT                   = 200  ; maximum loop count when waiting for rising/falling clock (TODO: Make frequency-dependant)
 
+.equ COM_MAINTENANCE_ADDR         = 0xf1
 
 .equ COM_BUFFER_FLAGS_DONE        = 0x80
 .equ COM_BUFFER_FLAGS_RECEIVED    = 0x40
@@ -36,6 +37,9 @@
 .equ COM_MSG_OFFS_DESTADDR        = 0
 .equ COM_MSG_OFFS_MSGLEN          = 1
 .equ COM_MSG_OFFS_MSGDATA         = 2
+.equ COM_MSG_OFFS_CMD             = 2 ; first at COM_MSG_OFFS_MSGDATA
+.equ COM_MSG_OFFS_SRCADDR         = 3
+.equ COM_MSG_OFFS_PAYLOAD         = 4 ; payload for the cmd follows here
 
 .equ COM_ERR_NOTFORME             = 1
 .equ COM_ERR_CHECKSUM             = 2
@@ -581,6 +585,8 @@ comReceivePacketToSram_acceptAddr:
   brcc comReceivePacketToSram_error
   eor r1, r16
   st X+, r16
+  cpi r16, (COM_BUFFER_SIZE-3-COM_BUFFER_OFFS_DATA)+1
+  brcc comReceivePacketToSram_error            ; packet too long (TODO: count overruns)
   tst r16
   breq comReceivePacketToSram_readXOR
   mov r17, r16
diff --git a/avr/comproto.asm b/avr/comproto.asm
index 321ddd4..d9010bd 100644
--- a/avr/comproto.asm
+++ b/avr/comproto.asm
@@ -18,6 +18,12 @@
 .equ CPRO_CMD_DENY_ADDRESS         = 63
 .equ CPRO_CMD_ADDRESS_RANGE        = 64
 
+.equ CPRO_CMD_FLASH_START          = 70
+.equ CPRO_CMD_FLASH_END            = 71
+.equ CPRO_CMD_FLASH_ADDR           = 72
+.equ CPRO_CMD_FLASH_DATA           = 73
+.equ CPRO_CMD_FLASH_RSP            = 74
+
 
 ; flags for variable payload enqueue function
 .equ CPRO_PAYLOAD_FLAGS_SECONDS    = 0x01
@@ -31,15 +37,20 @@
 .equ CPRO_PAYLOAD_FLAGS_SHIFT_NUM  = 5
 
 
-.equ CPRO_PACKET_OFFS_DESTADDR = 0
-.equ CPRO_PACKET_OFFS_MSGLEN   = 1
-.equ CPRO_PACKET_OFFS_CMD      = 2
-.equ CPRO_PACKET_OFFS_SRCADDR  = 3
-.equ CPRO_PACKET_OFFS_PAYLOAD  = 4
+.equ CPRO_PACKET_HAVEADDR_OFFS_ADDRESS  = COM_MSG_OFFS_PAYLOAD+4
+.equ CPRO_PACKET_CLAIMADDR_OFFS_ADDRESS = COM_MSG_OFFS_PAYLOAD+4
+.equ CPRO_PACKET_DENYADDR_OFFS_ADDRESS  = COM_MSG_OFFS_PAYLOAD+4
+
+.equ CPRO_PACKET_FLASH_START_OFFS_MSGNUM = COM_MSG_OFFS_PAYLOAD+0 ; 2 bytes
+.equ CPRO_PACKET_FLASH_START_OFFS_ADDR   = COM_MSG_OFFS_PAYLOAD+2 ; 2 bytes
+
+.equ CPRO_PACKET_FLASH_ADDR_OFFS_MSGNUM  = COM_MSG_OFFS_PAYLOAD+0 ; 2 bytes
+.equ CPRO_PACKET_FLASH_ADDR_OFFS_ADDR    = COM_MSG_OFFS_PAYLOAD+2 ; 2 bytes
+
+.equ CPRO_PACKET_FLASH_DATA_OFFS_MSGNUM  = COM_MSG_OFFS_PAYLOAD+0 ; 2 bytes
+.equ CPRO_PACKET_FLASH_DATA_OFFS_ADDR    = COM_MSG_OFFS_PAYLOAD+2 ; 2 bytes
+.equ CPRO_PACKET_FLASH_DATA_OFFS_DATA    = COM_MSG_OFFS_PAYLOAD+4 ; 2 bytes
 
-.equ CPRO_PACKET_HAVEADDR_OFFS_ADDRESS  = 8
-.equ CPRO_PACKET_CLAIMADDR_OFFS_ADDRESS = 8
-.equ CPRO_PACKET_DENYADDR_OFFS_ADDRESS  = 8
 
 .equ CPRO_WAITTIME_GETADDR       = 130
 .equ CPRO_WAITTIME_CLAIMADDR     = 17
@@ -64,11 +75,13 @@
 
 
 cproDataBegin:
+#ifndef BASE_SYSTEM
   cproMode:                .byte 1  ; "normal", "waitForHaveAddress", "samplingAddresses", "claimAddress"
   cproAddrRangeBegin:      .byte 1
   cproAddrRangeEnd:        .byte 1
   cproAddressWaitCounter:  .byte 1  ; counter for seconds to wait for all nodes to respond
   cproUsedAddresses:       .byte 16 ; one bit per address known to b in use
+#endif
 cproDataEnd:
 
 
@@ -93,6 +106,7 @@ CPRO_Init:
 
 
 CPRO_OnEverySecond:
+#ifndef BASE_SYSTEM
   lds r17, cproMode
   cpi r17, CPRO_MODE_NORMAL
   breq CPRO_OnEverySecond_done
@@ -121,6 +135,7 @@ CPRO_OnEverySecond_l6:
   brne CPRO_OnEverySecond_done
   rjmp cproHandle1sReclaimingAddr
 CPRO_OnEverySecond_done:
+#endif
   ret
 
 
@@ -137,11 +152,12 @@ CPRO_OnEverySecond_done:
 ; USED: depending on called routines
 
 CPRO_OnPacketReceived:
-  ldd r16, y+(COM_BUFFER_OFFS_DATA+CPRO_PACKET_OFFS_CMD)
+  ldd r16, y+(COM_BUFFER_OFFS_DATA+COM_MSG_OFFS_CMD)
   cpi r16, CPRO_CMD_PING
   brne CPRO_OnPacketReceived_l1
   rjmp cproHandlePing
 CPRO_OnPacketReceived_l1:
+#ifndef BASE_SYSTEM
   cpi r16, CPRO_CMD_NEED_ADDRESS
   brne CPRO_OnPacketReceived_l2
   rjmp cproHandlePckNeedAddr
@@ -162,12 +178,13 @@ CPRO_OnPacketReceived_l5:
   brne CPRO_OnPacketReceived_l6
   rjmp cproHandlePckClaimAddr
 CPRO_OnPacketReceived_l6:
+#endif
   clc
   ret
 
 
 cproHandlePing:
-  ldd r16, y+(COM_BUFFER_OFFS_DATA+CPRO_PACKET_OFFS_SRCADDR)
+  ldd r16, y+(COM_BUFFER_OFFS_DATA+COM_MSG_OFFS_SRCADDR)
   tst r16
   breq cproHandlePing_notHandled
   rcall CPRO_EnqueuePong
@@ -214,6 +231,7 @@ CPRO_EnqueuePong:
 
 
 
+#ifndef BASE_SYSTEM
 ; ---------------------------------------------------------------------------
 ; Enqueue a COM Send stats packet.
 ;
@@ -266,9 +284,11 @@ CPRO_EnqueueComSendStats_error:
   out SREG, r15
   clc
   ret
+#endif
 
 
 
+#ifndef BASE_SYSTEM
 ; ---------------------------------------------------------------------------
 ; Enqueue a TWI Bus Member packet.
 ;
@@ -316,9 +336,11 @@ CPRO_EnqueueTwiBusMember:
 CPRO_EnqueueTwiBusMember_error:
   clc
   ret
+#endif
 
 
 
+#ifndef BASE_SYSTEM
 ; ---------------------------------------------------------------------------
 ; Enqueue a DEBUG packet.
 ;
@@ -366,9 +388,11 @@ CPRO_EnqueueDebug:
 CPRO_EnqueueDebug_error:
   clc
   ret
+#endif
 
 
 
+#ifndef BASE_SYSTEM
 ; ---------------------------------------------------------------------------
 ; Enqueue a VALUE packet.
 ;
@@ -419,9 +443,11 @@ CPRO_EnqueueValue:
 CPRO_EnqueueValue_error:
   clc
   ret
+#endif
 
 
 
+#ifndef BASE_SYSTEM
 ; ---------------------------------------------------------------------------
 ; Enqueue a NEEDADDRESS packet.
 ;
@@ -434,9 +460,11 @@ CPRO_EnqueueValue_error:
 CPRO_EnqueueNeedAddress:
   ldi r18, CPRO_CMD_NEED_ADDRESS
   rjmp cproEnqueueAddressPacket
+#endif
 
 
 
+#ifndef BASE_SYSTEM
 ; ---------------------------------------------------------------------------
 ; Enqueue a HAVE_ADDRESS packet.
 ;
@@ -450,9 +478,11 @@ CPRO_EnqueueHaveAddress:
   ldi r18, CPRO_CMD_HAVE_ADDRESS
   lds r19, comAddress
   rjmp cproEnqueueAddressPacket
+#endif
 
 
 
+#ifndef BASE_SYSTEM
 ; ---------------------------------------------------------------------------
 ; Enqueue a CLAIM_ADDRESS packet.
 ;
@@ -465,9 +495,11 @@ CPRO_EnqueueHaveAddress:
 CPRO_EnqueueClaimAddress:
   ldi r18, CPRO_CMD_CLAIM_ADDRESS
   rjmp cproEnqueueAddressPacket
+#endif
 
 
 
+#ifndef BASE_SYSTEM
 ; ---------------------------------------------------------------------------
 ; Enqueue a DENY_ADDRESS packet.
 ;
@@ -481,9 +513,11 @@ CPRO_EnqueueDenyAddress:
   ldi r18, CPRO_CMD_DENY_ADDRESS
   lds r19, comAddress
   rjmp cproEnqueueAddressPacket
+#endif
 
 
 
+#ifndef BASE_SYSTEM
 ; ---------------------------------------------------------------------------
 ; cproEnqueueAddressPacket
 ; Enqueue a NEED/HAVE/CLAIM ADDRESS packet.
@@ -518,6 +552,7 @@ cproEnqueueAddressPacket:
 cproEnqueueAddressPacket_error:
   clc
   ret
+#endif
 
 
 
@@ -667,6 +702,51 @@ cproCalcPayloadSize_l2:
 
 
 
+#ifdef WITH_FLASH
+; ---------------------------------------------------------------------------
+; Enqueue a FLASHDATA_ACK packet.
+;
+; IN:
+; - R16: destination address
+; - R17: ACK(1) or NAK(0)
+; - R19:R18: msg num
+; OUT:
+; - CFLAG: set if okay, clear otherwise
+; MODIFIED REGS: R6, R7, R8, R9, R10, R11, R12, R16, R17, X, Y (R3, R4, R15, R16, R17, R18, R19, R20, R21)
+
+CPRO_EnqueueFlashRsp:
+  mov r6, r16
+  mov r7, r17
+  mov r8, r18
+  mov r9, r19
+
+  rcall COM_AllocBufferAndGetXY ; (r16, r17, r21)
+  brcc CPRO_EnqueueFlashRsp_error
+
+  push xh
+    push xl
+      mov r16, r6
+      ldi r17, CPRO_PAYLOAD_FLAGS_SECONDS | (3<<CPRO_PAYLOAD_FLAGS_SHIFT_NUM)
+      ldi r18, CPRO_CMD_FLASH_RSP
+      rcall cproBeginMsgWithVariablePayload  ; (R3, R4, R16, R17, R18, R19, R20, R21, X)
+      st X+, r8                              ; 4: msg num (low)
+      st X+, r9                              ; 5: msg num (high)
+      st X+, r7                              ; 6: ACK or NAK
+    pop xl
+  pop xh
+  rcall cproCalcAndAddChecksumByte
+
+  ; mark buffer as enqueued with PRIO "important" (higher number of retries)
+  ldi r20, COM_BUFFER_PRIO_IMPORTANT
+  rcall COM_EnqueuePacket      ; (R15, R16)
+  brcc CPRO_EnqueueFlashRsp_error
+  sec
+  ret
+CPRO_EnqueueFlashRsp_error:
+  clc
+  ret
+#endif
+
 
 
 
diff --git a/avr/lcd.asm b/avr/lcd.asm
index 744ad10..ab5aeb4 100644
--- a/avr/lcd.asm
+++ b/avr/lcd.asm
@@ -398,7 +398,7 @@ LCD_PrintHexWord_errorNoPop:
 ; ---------------------------------------------------------------------------
 ; lcdPrintHexWord
 ;
-; Convert a give word into HEX and write it to the current position.
+; Convert a given word into HEX and write it to the current position.
 ;
 ; IN:
 ; - r18: low byte of the word
@@ -554,6 +554,32 @@ lcdPrintOneChar_error:
 ; REGS: r16, r17, Z
 
 lcdGetCharMatrix:
+#ifdef LCD_MINIMAL_FONT
+  rcall lcdUpcase
+  cpi r16, 65+32
+  brcc lcdGetCharMatrix_l1
+  cpi r16, 32
+  brcc lcdGetCharMatrix_l2
+lcdGetCharMatrix_l1:
+  ldi r16, 32
+lcdGetCharMatrix_l2:
+  ldi r17, 32
+  sub r16, r17
+  mov zl, r16
+  clr zh
+  clr r17
+  lsl zl      ; *2
+  rol zh
+  add zl, r16 ; *3
+  adc zh, r17
+  lsl zl      ; *6
+  rol zh
+  ldi r16, LOW(lcdFont6x8Minimal*2)
+  ldi r17, HIGH(lcdFont6x8Minimal*2)
+  add zl, r16
+  adc zh, r17
+  ret
+#else
   cpi r16, 95+32
   brcc lcdGetCharMatrix_l1
   cpi r16, 32
@@ -577,6 +603,29 @@ lcdGetCharMatrix_l2:
   add zl, r16
   adc zh, r17
   ret
+#endif
+
+
+#ifdef LCD_MINIMAL_FONT
+; ---------------------------------------------------------------------------
+; Uppercase the given character if it is lower case.
+;
+; IN:
+; - R16: char
+; OUT:
+; - R16: char
+; REGS: r16, r17
+
+lcdUpcase:
+  cpi r16, 'a'
+  brcs lcdUpcase_done
+  cpi r16, 'z'+1
+  brcc lcdUpcase_done
+  ldi r17, 32
+  sub r16, r17
+lcdUpcase_done:
+  ret
+#endif
 
 
 ; TODO: set adressing mode??
@@ -589,6 +638,74 @@ lcdHelloMsg: .db "AqHOME 2023", 0
 
 ; font taken from Tiny4kOLED (https://github.com/datacute/Tiny4kOLED/tree/master/src) by Stephen Denne (MIT license),
 ; original by Neven Boyanov
+#ifdef LCD_MINIMAL_FONT
+lcdFont6x8Minimal:
+  .db 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ;   0 
+  .db 0x00, 0x00, 0x00, 0x2f, 0x00, 0x00 ; ! 1 
+  .db 0x00, 0x00, 0x07, 0x00, 0x07, 0x00 ; " 2 
+  .db 0x00, 0x14, 0x7f, 0x14, 0x7f, 0x14 ; # 3 
+  .db 0x00, 0x24, 0x2a, 0x7f, 0x2a, 0x12 ; $ 4 
+  .db 0x00, 0x62, 0x64, 0x08, 0x13, 0x23 ; % 5 
+  .db 0x00, 0x36, 0x49, 0x55, 0x22, 0x50 ; & 6 
+  .db 0x00, 0x00, 0x05, 0x03, 0x00, 0x00 ; ' 7 
+  .db 0x00, 0x00, 0x1c, 0x22, 0x41, 0x00 ; ( 8 
+  .db 0x00, 0x00, 0x41, 0x22, 0x1c, 0x00 ; ) 9 
+  .db 0x00, 0x14, 0x08, 0x3E, 0x08, 0x14 ; * 10
+  .db 0x00, 0x08, 0x08, 0x3E, 0x08, 0x08 ; + 11
+  .db 0x00, 0x00, 0x00, 0xA0, 0x60, 0x00 ; , 12
+  .db 0x00, 0x08, 0x08, 0x08, 0x08, 0x08 ; - 13
+  .db 0x00, 0x00, 0x60, 0x60, 0x00, 0x00 ; . 14
+  .db 0x00, 0x20, 0x10, 0x08, 0x04, 0x02 ; / 15
+  .db 0x00, 0x3E, 0x51, 0x49, 0x45, 0x3E ; 0 16
+  .db 0x00, 0x00, 0x42, 0x7F, 0x40, 0x00 ; 1 17
+  .db 0x00, 0x42, 0x61, 0x51, 0x49, 0x46 ; 2 18
+  .db 0x00, 0x21, 0x41, 0x45, 0x4B, 0x31 ; 3 19
+  .db 0x00, 0x18, 0x14, 0x12, 0x7F, 0x10 ; 4 20
+  .db 0x00, 0x27, 0x45, 0x45, 0x45, 0x39 ; 5 21
+  .db 0x00, 0x3C, 0x4A, 0x49, 0x49, 0x30 ; 6 22
+  .db 0x00, 0x01, 0x71, 0x09, 0x05, 0x03 ; 7 23
+  .db 0x00, 0x36, 0x49, 0x49, 0x49, 0x36 ; 8 24
+  .db 0x00, 0x06, 0x49, 0x49, 0x29, 0x1E ; 9 25
+  .db 0x00, 0x00, 0x36, 0x36, 0x00, 0x00 ; : 26
+  .db 0x00, 0x00, 0x56, 0x36, 0x00, 0x00 ; ; 27
+  .db 0x00, 0x08, 0x14, 0x22, 0x41, 0x00 ; < 28
+  .db 0x00, 0x14, 0x14, 0x14, 0x14, 0x14 ; = 29
+  .db 0x00, 0x00, 0x41, 0x22, 0x14, 0x08 ; > 30
+  .db 0x00, 0x02, 0x01, 0x51, 0x09, 0x06 ; ? 31
+  .db 0x00, 0x32, 0x49, 0x59, 0x51, 0x3E ; @ 32
+  .db 0x00, 0x7C, 0x12, 0x11, 0x12, 0x7C ; A 33
+  .db 0x00, 0x7F, 0x49, 0x49, 0x49, 0x36 ; B 34
+  .db 0x00, 0x3E, 0x41, 0x41, 0x41, 0x22 ; C 35
+  .db 0x00, 0x7F, 0x41, 0x41, 0x22, 0x1C ; D 36
+  .db 0x00, 0x7F, 0x49, 0x49, 0x49, 0x41 ; E 37
+  .db 0x00, 0x7F, 0x09, 0x09, 0x09, 0x01 ; F 38
+  .db 0x00, 0x3E, 0x41, 0x49, 0x49, 0x7A ; G 39
+  .db 0x00, 0x7F, 0x08, 0x08, 0x08, 0x7F ; H 40
+  .db 0x00, 0x00, 0x41, 0x7F, 0x41, 0x00 ; I 41
+  .db 0x00, 0x20, 0x40, 0x41, 0x3F, 0x01 ; J 42
+  .db 0x00, 0x7F, 0x08, 0x14, 0x22, 0x41 ; K 43
+  .db 0x00, 0x7F, 0x40, 0x40, 0x40, 0x40 ; L 44
+  .db 0x00, 0x7F, 0x02, 0x0C, 0x02, 0x7F ; M 45
+  .db 0x00, 0x7F, 0x04, 0x08, 0x10, 0x7F ; N 46
+  .db 0x00, 0x3E, 0x41, 0x41, 0x41, 0x3E ; O 47
+  .db 0x00, 0x7F, 0x09, 0x09, 0x09, 0x06 ; P 48
+  .db 0x00, 0x3E, 0x41, 0x51, 0x21, 0x5E ; Q 49
+  .db 0x00, 0x7F, 0x09, 0x19, 0x29, 0x46 ; R 50
+  .db 0x00, 0x46, 0x49, 0x49, 0x49, 0x31 ; S 51
+  .db 0x00, 0x01, 0x01, 0x7F, 0x01, 0x01 ; T 52
+  .db 0x00, 0x3F, 0x40, 0x40, 0x40, 0x3F ; U 53
+  .db 0x00, 0x1F, 0x20, 0x40, 0x20, 0x1F ; V 54
+  .db 0x00, 0x3F, 0x40, 0x38, 0x40, 0x3F ; W 55
+  .db 0x00, 0x63, 0x14, 0x08, 0x14, 0x63 ; X 56
+  .db 0x00, 0x07, 0x08, 0x70, 0x08, 0x07 ; Y 57
+  .db 0x00, 0x61, 0x51, 0x49, 0x45, 0x43 ; Z 58
+  .db 0x00, 0x00, 0x7F, 0x41, 0x41, 0x00 ; [ 59
+  .db 0x00, 0x02, 0x04, 0x08, 0x10, 0x20 ; \ 60
+  .db 0x00, 0x00, 0x41, 0x41, 0x7F, 0x00 ; ] 61
+  .db 0x00, 0x04, 0x02, 0x01, 0x02, 0x04 ; ^ 62
+  .db 0x00, 0x40, 0x40, 0x40, 0x40, 0x40 ; _ 63
+  .db 0x00, 0x00, 0x01, 0x02, 0x04, 0x00 ; ' 64
+#else
 lcdFont6x8:
   .db 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ;   0 
   .db 0x00, 0x00, 0x00, 0x2f, 0x00, 0x00 ; ! 1 
@@ -685,6 +802,7 @@ lcdFont6x8:
   .db 0x00, 0x00, 0x00, 0x7F, 0x00, 0x00 ; | 92
   .db 0x00, 0x00, 0x41, 0x41, 0x36, 0x08 ; } 93
   .db 0x00, 0x08, 0x04, 0x08, 0x10, 0x08 ; ~ 94
+#endif
 
 
 
diff --git a/avr/main.asm b/avr/main.asm
index ed4da9f..aa254cc 100644
--- a/avr/main.asm
+++ b/avr/main.asm
@@ -18,6 +18,7 @@ main:
   rcall onSystemStart
 
 
+#ifdef MODULES_LED
   ldi xl, LOW(blinkPattern)  ; debug: set blink pattern
   ldi xh, HIGH(blinkPattern)
   ldi zl, LOW(ledA3Flash)
@@ -25,6 +26,7 @@ main:
   ldi yl, LOW(ledA3Sram)
   ldi yh, HIGH(ledA3Sram)
   rcall Led_SetPattern
+#endif
 
 ;  ldi r16, 1
 ;  sts twiMasterScanEnabled, r16
@@ -135,33 +137,12 @@ runModulesUntilIdle_ComEnd:
 
 
 
+#ifdef MODULES_LCD
 printSendStats:
   push r15
     in r15, SREG ; debug
     cli
 
-#ifdef MODULES_SI7021
-    ldi r18, 0
-    ldi r19, 1
-    rcall LCD_SetCursor
-    ldi zl, LOW(textSi7021Firmware)
-    ldi zh, HIGH(textSi7021Firmware)
-    rcall LCD_PrintFromFlash
-
-    lds r16, si7021Flags
-    rcall LCD_PrintHexByte
-    ldi r16, 32
-    rcall LCD_PrintChar
-    lds r18, si7021LastTemp
-    lds r19, si7021LastTemp+1
-    rcall LCD_PrintHexWord
-    ldi r16, 32
-    rcall LCD_PrintChar
-    lds r18, si7021LastHumidity
-    lds r19, si7021LastHumidity+1
-    rcall LCD_PrintHexWord
-#endif
-
     ldi r18, 0
     ldi r19, 2
     rcall LCD_SetCursor
@@ -241,6 +222,7 @@ printSendStats:
   pop r15
   out SREG, r15
   ret
+#endif
 
 
 
@@ -287,19 +269,18 @@ sendValueMsg_done:
   pop r15
   out SREG, r15
   ret
-#endif
-#endif
 
 
-textSi7021Firmware:      .db "SI: ", 0, 0
 textStatsPacketsIn:      .db "In     : ", 0
 textStatsPacketsRecvErr: .db "RecvErr: ", 0
 textStatsPacketsOut:     .db "Out    : ", 0
 textUid:                 .db "UID    : ", 0
-textRandom:              .db "RANDOM : ", 0
 textAddress:             .db "ADDR   :", 0, 0
 textBitmap:              .db "BITMAP :", 0, 0
 
+#endif
+#endif
+
 
 
 
diff --git a/avr/utils.asm b/avr/utils.asm
index c857d8d..396ee6e 100644
--- a/avr/utils.asm
+++ b/avr/utils.asm
@@ -146,6 +146,7 @@ Utils_FillSram_end:
 
 
 
+#if 0
 ; ---------------------------------------------------------------------------
 ; Increment a 32 bit counter at the address given by X.
 ; IN:
@@ -170,6 +171,7 @@ Utils_IncrementCounter32:
   st -x, r19
   st -x, r18
   ret
+#endif
 
 
 
@@ -243,105 +245,6 @@ Utils_WriteEeprom:
 
 
 
-
-
-
-; ---------------------------------------------------------------------------
-; Utils_ReadFlashPageIntoPageBuffer
-;
-;
-; IN:
-; - Z: Address to read from (byte address as for LPM!)
-; OUT:
-; - nothing
-; MODIFIED REGISTERS: R0, R1, R15, R16, R20, R24, R25, Z
-
-Utils_ReadFlashPageIntoPageBuffer:
-  in r15, SREG
-  cli
-    ldi r24, LOW(PAGESIZE*2)
-    ldi r25, HIGH(PAGESIZE*2)
-Utils_ReadFlashPageIntoPageBuffer_loop:
-      lpm r0, Z+                                ; read source data from FLASH (low)
-      lpm r1, Z                                 ; read source data from FLASH (high)
-      sbiw ZH:ZL, 1                             ; rewind Z address for following SPM
-      ldi r20, (1<<SPMEN)                       ; enable next SPM, write into temp page buffer
-      rcall utilsDoSpm                          ; (R16)
-      adiw ZH:ZL, 2
-      sbiw r25:r24, 2                           ;use subi for PAGESIZEB<=256
-    brne Utils_ReadFlashPageIntoPageBuffer_loop
-  out SREG, r15
-  ret
-
-
-
-; ---------------------------------------------------------------------------
-; Utils_EraseFlashPage
-;
-;
-; IN:
-; - Z: Address of the page to erase.
-; OUT:
-; - nothing
-; MODIFIED REGISTERS: R0, R1, R15, R16, R18, R19, R20
-
-Utils_EraseFlashPage:
-  in r15, SREG
-  cli
-    ldi r20, (1<<PGERS) + (1<<SPMEN)          ; enable next SPM, erase page (R1/R0 ignored)
-    rcall utilsDoSpm                          ; (R16)
-  out SREG, r15
-  ret
-
-
-
-; ---------------------------------------------------------------------------
-; Utils_WriteFlashPage
-;
-;
-; IN:
-; - Z: Address of the page to erase.
-; OUT:
-; - nothing
-; MODIFIED REGISTERS: R0, R1, R15, R16, R18, R19, R20
-
-Utils_WriteFlashPage:
-  in r15, SREG
-  cli
-    ldi r20, (1<<PGWRT) + (1<<SPMEN)          ; enable next SPM, erase page (R1/R0 ignored)
-    rcall utilsDoSpm                          ; (R16)
-  out SREG, r15
-  ret
-
-
-
-; ---------------------------------------------------------------------------
-; utilsDoSpm
-;
-; wait until possible previous SPM finished and then issue another SPM.
-;
-; IN:
-; - R20: value for register SPMCR
-; - R0:  low value for SPM
-; - R1:  high value for SPM
-; - Z  : address for SPM (byte address!)
-; OUT:
-; - nothing
-; REGS: R16
-
-utilsDoSpm:
-wait:                ; wait for possibly previous SPM to complete
-    in r16, SPMCSR
-    sbrc r16, SPMEN
-  rjmp wait
-  ; SPM timed sequence
-  out SPMCSR, r20
-  spm
-  ret
-
-
-
-
 ; ---------------------------------------------------------------------------
 ; Utils_PseudoRandom
 ;