diff --git a/avr/devices/0BUILD b/avr/devices/0BUILD
index 23e950c..2b8a75b 100644
--- a/avr/devices/0BUILD
+++ b/avr/devices/0BUILD
@@ -23,6 +23,7 @@
     n28
     n29
     n30
+    n31
     r06
     s03
     t03
diff --git a/avr/devices/n31/.gitignore b/avr/devices/n31/.gitignore
new file mode 100644
index 0000000..25dc86f
--- /dev/null
+++ b/avr/devices/n31/.gitignore
@@ -0,0 +1,4 @@
+*.eep.hex
+*.obj
+n29-enclosure.stl
+n29-enclosure-2.stl
diff --git a/avr/devices/n31/0BUILD b/avr/devices/n31/0BUILD
new file mode 100644
index 0000000..3f7db52
--- /dev/null
+++ b/avr/devices/n31/0BUILD
@@ -0,0 +1,19 @@
+<?xml?>
+
+<gwbuild>
+
+  <subdirs>
+    boot
+    main
+  </subdirs>
+
+  <extradist>
+    defs.asm
+    README
+    enclosure.scad
+  </extradist>
+  
+
+</gwbuild>
+
+
diff --git a/avr/devices/n31/README b/avr/devices/n31/README
new file mode 100644
index 0000000..0a08578
--- /dev/null
+++ b/avr/devices/n31/README
@@ -0,0 +1,17 @@
+
+N31
+===
+
+- Role: Air quality sensors
+- MCU: AtTiny84
+- Frequency: 1MHz
+- Connection: RJ45
+- Predecessor: N26
+- COM: COM2W
+- Periphery:
+  - TWI interface
+    - SGP-30/40 air quality sensor
+- Apps:
+  - NETWORK:       Basic network functionality (address setup etc.)
+  - REPORTSENSORS: report sensor data from temperature sensor etc.
+  - STATS        : periodically send stats data
diff --git a/avr/devices/n31/boot/0BUILD b/avr/devices/n31/boot/0BUILD
new file mode 100644
index 0000000..9651a6f
--- /dev/null
+++ b/avr/devices/n31/boot/0BUILD
@@ -0,0 +1,32 @@
+<?xml?>
+
+<gwbuild>
+
+  <target type="AvrHexFile" name="n31_boot" >
+
+    <includes type="avrasm" >
+      -I $(builddir)
+      -I $(srcdir)
+      -I $(topsrcdir)/avr
+      -I $(topbuilddir)/avr
+    </includes>
+
+
+    <sources type="avrasm" >
+      boot.asm
+    </sources>
+
+
+  </target>
+
+
+  <subdirs>
+  </subdirs>
+
+  <extradist>
+  </extradist>
+  
+
+</gwbuild>
+
+
diff --git a/avr/devices/n31/boot/boot.asm b/avr/devices/n31/boot/boot.asm
new file mode 100644
index 0000000..7f35036
--- /dev/null
+++ b/avr/devices/n31/boot/boot.asm
@@ -0,0 +1,157 @@
+; ***************************************************************************
+; copyright   : (C) 2026 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.   *
+; ***************************************************************************
+
+
+; ***************************************************************************
+; Source file for base system node on AtTiny 84
+;
+; This is for the maintenance system (i.e. the flash loader).
+;
+; All definitions and changes should go into this file.
+; ***************************************************************************
+
+.equ clock=1000000 ; Define the clock frequency
+
+.nolist
+.include "include/tn84def.inc" ; Define device ATtiny84
+.list
+
+.include "version.asm"
+.include "../defs.asm"
+
+.include "common/calls.asm"
+.include "common/utils_io.asm"
+.include "devices/all/defs.asm"
+
+
+#define COM_ACCEPT_ALL_DEST
+
+
+
+; ***************************************************************************
+; defines
+
+; ---------------------------------------------------------------------------
+; generic
+
+.include "common/utils_wait.asm"
+.include "modules/com2/defs.asm"
+.include "modules/comproto/defs.asm"
+
+
+
+; ---------------------------------------------------------------------------
+; firmware settings
+
+
+
+; ---------------------------------------------------------------------------
+; LED
+
+.equ LED_DDR             = DDRA
+.equ LED_PORT            = PORTA
+.equ LED_PIN             = PINA
+.equ LED_PINNUM          = PORTA3
+
+
+; ***************************************************************************
+; code segment
+
+.cseg
+.org 0x0000
+
+
+
+; ---------------------------------------------------------------------------
+; Reset and interrupt vectors
+;  rjmp start ; Reset vector
+  rjmp main ; Reset vector
+  reti ; EXT_INT0
+  reti ; PCI0
+  reti ; PCI1
+  reti ; WATCHDOG
+  reti ; ICP1
+  reti ; OC1A
+  reti ; OC1B
+  reti ; OVF1
+  reti ; OC0A
+  reti ; OC0B
+  reti ; OVF0
+  reti ; ACI
+  reti ; ADCC
+  reti ; ERDY
+  reti ; USI_STR
+  reti ; USI_OVF
+
+
+devInfoBlock:        ; 12 bytes
+devInfoManufacturer: .db 'A', 'Q', 'U', 'A'
+devInfoId:           .db DEVICEINFO_ID, 0
+devInfoVersion:      .db DEVICEINFO_VERSION, DEVICEINFO_REVISION             ; version, revision
+firmwareVersion:     .db FIRMWARE_VARIANT_BOOT, FIRMWARE_VERSION_MAJOR
+                     .db FIRMWARE_VERSION_MINOR, FIRMWARE_VERSION_PATCHLEVEL
+
+firmwareStart:   rjmp main ; will be overwritten when flashing
+
+
+
+; ***************************************************************************
+; main code
+
+
+.org BOOTLOADER_ADDR
+
+
+main:
+  rjmp bootLoader ; this routine is in modules/bootloader/main.asm
+
+
+
+; ***************************************************************************
+; includes
+
+.include "common/utils_wait_fixed.asm"
+.include "common/utils_copy_from_flash.asm"
+.include "common/utils_copy_sdram.asm"
+
+.include "modules/flash/defs.asm"
+.include "modules/flash/eeprom.asm"
+.include "modules/flash/io.asm"
+.include "modules/flash/io_com2w.asm"
+.include "modules/flash/flash1p.asm"
+.include "modules/flash/flashxp.asm"
+.include "modules/flash/flashprocess.asm"
+.include "modules/flash/wait.asm"
+.include "modules/bootloader/main.asm"
+.include "modules/network/msg/defs.asm"
+.include "modules/network/msg/crc.asm"
+
+;.include "common/debug.asm"
+
+
+
+systemSetSpeed:
+.if clock == 8000000
+  ldi r16, (1<<CLKPCE)
+  ldi r17, 0
+  out CLKPR, r16
+  out CLKPR, r17
+.endif
+
+.if clock == 1000000
+  ldi r16, (1<<CLKPCE)
+  ldi r17, (1<<CLKPS1) | (1<<CLKPS0)
+  out CLKPR, r16
+  out CLKPR, r17
+.endif
+  ret
+
+
+
+
diff --git a/avr/devices/n31/defs.asm b/avr/devices/n31/defs.asm
new file mode 100644
index 0000000..f2d60b7
--- /dev/null
+++ b/avr/devices/n31/defs.asm
@@ -0,0 +1,114 @@
+; ***************************************************************************
+; copyright   : (C) 2026 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.   *
+; ***************************************************************************
+
+
+; ***************************************************************************
+;
+;                                 AtTiny84
+;                                 --------
+;                            VCC  1     14  GND
+;                            PB0  2     13  PA0  LED_YELLOW
+;                            PB1  3     12  PA1  COM-DATA
+;                  /RESET    PB3  4     11  PA2  LED_RED
+;                            PB2  5     10  PA3  LED_GREEN
+;                  COM_CLK   PA7  6      9  PA4  TWI-SCL
+;                  TWI-SDA   PA6  7      8  PA5
+;                                 --------
+;
+; ***************************************************************************
+
+
+
+.equ BOOTLOADER_ADDR = 0xd00
+
+.equ FIRMWARE_VARIANT_BOOT        = 0
+.equ FIRMWARE_VARIANT_TEMP_WINDOW = 1
+
+.equ DEVICEINFO_ID       = 'N'
+.equ DEVICEINFO_VERSION  = 31
+.equ DEVICEINFO_REVISION = 0
+
+
+
+; ---------------------------------------------------------------------------
+; LED module
+
+.equ LED_SIMPLE_ONTIME  = 1     ; shorter
+.equ LED_SIMPLE_OFFTIME = 99    ; longer
+.equ LED_SIMPLE_DDR     = DDRA
+.equ LED_SIMPLE_PORT    = PORTA
+.equ LED_SIMPLE_PORTIN  = PINA
+.equ LED_SIMPLE_PINNUM  = PORTA3
+
+
+
+; ---------------------------------------------------------------------------
+; LED Activity module
+
+.equ LED_ACTIVITY_DDR     = DDRA
+.equ LED_ACTIVITY_PORT    = PORTA
+.equ LED_ACTIVITY_PORTIN  = PINA
+.equ LED_ACTIVITY_PINNUM  = PORTA3
+
+
+
+; ---------------------------------------------------------------------------
+; COM module
+
+.equ COM_BIT_LENGTH      = 52000 ; 104000ns=9600, 52000ns=19200, 26000ns=38400
+.equ COM_HALFBIT_LENGTH  = 26000 ; see https://de.wikipedia.org/wiki/Universal_Asynchronous_Receiver_Transmitter
+
+.equ COM_DATA_DDR       = DDRA
+.equ COM_DATA_INPUT     = PINA
+.equ COM_DATA_OUTPUT    = PORTA
+.equ COM_DATA_PIN       = PORTA1
+
+.equ COM_CLK_DDR       = DDRA
+.equ COM_CLK_INPUT     = PINA
+.equ COM_CLK_OUTPUT    = PORTA
+.equ COM_CLK_PIN       = PORTA7
+
+.equ COM_IRQ_ADDR_CLK   = PCMSK0
+.equ COM_IRQ_BIT_CLK    = PCINT7        ; bit 7 in PCMSK0
+.equ COM_IRQ_GIFR_CLK   = PCIF0
+.equ COM_IRQ_GIMSK_CLK  = PCIE0
+
+
+
+; ---------------------------------------------------------------------------
+; TWI master module
+
+;.equ TWI_BIT_LENGTH = 10000 ; 100000 and 200000 works for display: 10000, 100000, 200000
+.equ TWI_BIT_LENGTH = 1 ; 10, 100, 500, 100000 and 200000 works for display: 10000, 100000, 200000
+
+.equ TWI_DDR_SCL          = DDRA
+.equ TWI_PORT_SCL         = PORTA
+.equ TWI_PIN_SCL          = PINA
+.equ TWI_PINNUM_SCL       = PORTA4
+
+.equ TWI_DDR_SDA          = DDRA
+.equ TWI_PORT_SDA         = PORTA
+.equ TWI_PIN_SDA          = PINA
+.equ TWI_PINNUM_SDA       = PORTA6
+
+
+
+; ---------------------------------------------------------------------------
+; SGB 30
+
+.equ SGP30_ADDR           = 0x58
+
+
+
+; ---------------------------------------------------------------------------
+; SGB 40
+
+.equ SGP40_ADDR           = 0x59
+
+
diff --git a/avr/devices/n31/enclosure.scad b/avr/devices/n31/enclosure.scad
new file mode 100644
index 0000000..ecbd64c
--- /dev/null
+++ b/avr/devices/n31/enclosure.scad
@@ -0,0 +1,244 @@
+$fn = 50;
+
+width = 45;
+length = 60;
+height = 20;
+
+corner_radius = 2;
+wall_thickness = 1.5;
+post_diameter = 8;
+post_height = 0;
+
+hole_diameter = 3;
+
+lid_height = 4;
+lid_tolerance = .3;
+
+hook_height = 1;
+hook_tolerance = 0.75;
+hook_slit_height = 2.5;
+
+airslit_height = 1.75;
+
+ridge_height = 16;
+ridge_width = 1;
+ridge_depth = 2.5;
+
+netconn_width = 17;
+netcomm_length = 6;
+netcomm_height = 20;
+netcomm_tolerance = .3;
+
+
+
+module posts(x, y, z, h, r){
+    translate([x, y, z])
+      cylinder(r = r, h = h);
+
+    translate([-x, y, z])
+      cylinder(r = r, h = h);
+
+    translate([-x, -y, z])
+      cylinder(r = r, h = h);
+
+    translate([x, -y, z])
+      cylinder(r = r, h = h);
+}
+
+
+union() {
+    difference() {
+        // box
+        hull() {
+            posts(
+                x=(width/2 - corner_radius), 
+                y=(length/2 - corner_radius),
+                z=0,
+                h=height,
+                r=corner_radius);
+        }
+        
+        // hollow
+        hull() {
+            posts(
+                x=(width/2 - corner_radius - wall_thickness), 
+                y=(length/2 - corner_radius - wall_thickness),
+                z=wall_thickness,
+                h=height,
+                r=corner_radius);
+        }
+    
+        // lip inside box
+        *hull() {
+            posts(
+                x=(width/2 - corner_radius - lid_lip), 
+                y=(length/2 - corner_radius - lid_lip),
+                z=(height - lid_thickness),
+                h=(lid_thickness + 1),
+                r=corner_radius);
+        }
+    
+        // ventilation slits left 1
+        for(i = [(wall_thickness+post_height+3):(airslit_height*2):(height-5)]) {
+            translate([(-width/2)-wall_thickness, (-length/4), i])
+                cube([10, length/5, airslit_height], center=true);
+        }
+    
+        // ventilation slits top
+        for(i = [(wall_thickness+post_height+3):(airslit_height*2):(height-5)]) {
+            translate([0, -(length/2), i])
+                cube([width/2, 10, airslit_height], center=true);
+        }
+    
+        // ventilation slits right 1
+        for(i = [(wall_thickness+post_height+3):(airslit_height*2):(height-5)]) {
+            translate([(width/2)-wall_thickness, (-length/4), i])
+                cube([10, length/5, 1.75], center=true);
+        }
+       
+        // network connector hole 1
+        translate([(netconn_width-netcomm_tolerance)/2, 
+                    (length/2),
+                    wall_thickness+2+10])
+            cube([netconn_width+netcomm_tolerance,
+                  netcomm_length,
+                  netcomm_height],
+                 center=true);
+    
+        // network connector hole 2
+        translate([-(netconn_width-netcomm_tolerance)/2, 
+                    (length/2),
+                    wall_thickness+2+10])
+            cube([netconn_width+netcomm_tolerance,
+                  netcomm_length,
+                  netcomm_height],
+                 center=true);
+
+        // LED holes
+        translate([12, -16, -wall_thickness])
+          cylinder(r = 5.5/2, h = 6);
+
+        translate([4.254, -16, -wall_thickness])
+          cylinder(r = 5.5/2, h = 6);
+
+        translate([-3.484, -16, -wall_thickness])
+          cylinder(r = 5.5/2, h = 6);
+
+    
+    }
+
+     // hooks upward facing side
+     translate([-(width/2)-0.25, length/8, height-(hook_height/2)])
+       cube([2.5, 7, hook_height], center=true);
+     translate([-(width/2)-0.25, -length/8, height-(hook_height/2)])
+       cube([2.5, 7, hook_height], center=true);
+
+    // hooks downward facing side
+    translate([(width/2)+0.25, length/8, height-(hook_height/2)])
+      cube([2.5, 7, hook_height], center=true);
+    translate([(width/2)+0.25, -length/8, height-(hook_height/2)])
+      cube([2.5, 7, hook_height], center=true);
+
+    // ridges to hold the pcb
+    translate([(width/2)-wall_thickness, 0, ridge_height/2+(height-ridge_height)])
+      cube([ridge_depth, ridge_width, ridge_height], center=true);
+
+    translate([-((width/2)-wall_thickness), 
+               length/8,
+               ridge_height/2+(height-ridge_height)])
+      cube([ridge_depth, ridge_width, ridge_height], center=true);
+
+    translate([-((width/2)-wall_thickness), 
+               -length/8,
+               ridge_height/2+(height-ridge_height)])
+      cube([ridge_depth, ridge_width, ridge_height], center=true);
+
+
+}
+
+
+/* lid */
+translate([0, 0, 50]) { /* match at Z=16.5, otherwise 50*/
+  difference() {
+    union() {
+        difference() {
+            hull() {
+                posts(
+                      x=(width/2 - corner_radius + wall_thickness + lid_tolerance), 
+                      y=(length/2 - corner_radius + lid_tolerance),
+                      z=0,
+                      h=lid_height+wall_thickness,
+                      r=corner_radius);
+            }
+
+            hull() {
+                posts(
+                      x=(width/2 - corner_radius ), 
+                      y=(length/2 - corner_radius)+5,
+                      z=-(wall_thickness),
+                      h=lid_height+wall_thickness,
+                      r=corner_radius);
+            }
+
+            // slits for hooks (upward facing side)
+            translate([-((width/2)+wall_thickness/2),
+                       length/8,
+                       lid_height-((hook_slit_height)/2)])
+                cube([4, 9, hook_slit_height], center=true);
+            translate([-((width/2)+wall_thickness/2),
+                       -length/8,
+                       lid_height-((hook_slit_height)/2)])
+                cube([4, 9, hook_slit_height], center=true);
+
+            // slits for hooks (downward facing side)
+            translate([(width/2)+(wall_thickness/2),
+                       length/8,
+                       lid_height-((hook_slit_height)/2)])
+                cube([4, 9, hook_slit_height], center=true);
+            translate([(width/2)+(wall_thickness/2),
+                       -length/8,
+                       lid_height-((hook_slit_height)/2)])
+                cube([4, 9, hook_slit_height], center=true);
+        }
+        
+   
+        // hooks downward facing side
+        *translate([(width/2)-lid_lip, 0, 1])
+            cube([2, 5, hook_thickness], center=true);
+        *translate([(width/2)-lid_lip, length/4, 1])
+            cube([2, 5, hook_thickness], center=true);
+        *translate([(width/2)-lid_lip, -length/4, 1])
+            cube([2, 5, hook_thickness], center=true);
+    
+      }
+
+    // drilling holes    
+    translate([0, 0, -wall_thickness])
+      cylinder(r = hole_diameter, h = 10);
+
+    translate([0, -(length/3), -wall_thickness])
+      cylinder(r = hole_diameter, h = 10);
+      
+ }
+}
+
+
+
+// support posts for pcb
+/*difference() {
+    translate([0, length/4, wall_thickness])
+        cylinder(r = post_diameter/2, h = post_height);
+
+    translate([0, length/4, wall_thickness])
+        cylinder(r = hole_diameter/2, h = post_height+3);
+}
+
+
+difference() {
+    translate([0, -length/4, wall_thickness])
+        cylinder(r = post_diameter/2, h = post_height);
+
+    translate([0, -length/4, wall_thickness])
+        cylinder(r = hole_diameter/2, h = post_height+3);
+}
+*/
\ No newline at end of file
diff --git a/avr/devices/n31/main/0BUILD b/avr/devices/n31/main/0BUILD
new file mode 100644
index 0000000..0239cd5
--- /dev/null
+++ b/avr/devices/n31/main/0BUILD
@@ -0,0 +1,34 @@
+<?xml?>
+
+<gwbuild>
+
+  <target type="AvrHexFile" name="n31_firmware" >
+
+    <includes type="avrasm" >
+      -I $(builddir)
+      -I $(srcdir)
+      -I $(topsrcdir)/avr
+      -I $(topbuilddir)/avr
+    </includes>
+
+
+    <sources type="avrasm" >
+      main.asm
+    </sources>
+
+
+  </target>
+
+
+
+  <subdirs>
+  </subdirs>
+
+  <extradist>
+    data.asm
+  </extradist>
+  
+
+</gwbuild>
+
+
diff --git a/avr/devices/n31/main/data.asm b/avr/devices/n31/main/data.asm
new file mode 100644
index 0000000..31ccc2f
--- /dev/null
+++ b/avr/devices/n31/main/data.asm
@@ -0,0 +1,14 @@
+; ***************************************************************************
+; 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.   *
+; ***************************************************************************
+
+
+
+.dseg
+
+
diff --git a/avr/devices/n31/main/main.asm b/avr/devices/n31/main/main.asm
new file mode 100644
index 0000000..1e39c94
--- /dev/null
+++ b/avr/devices/n31/main/main.asm
@@ -0,0 +1,215 @@
+; ***************************************************************************
+; copyright   : (C) 2026 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.   *
+; ***************************************************************************
+
+
+
+
+; ***************************************************************************
+; Source file for temperature sensor node on AtTiny 84
+;
+; This is for the full system (i.e. not the boot loader).
+;
+; All definitions and changes should go into this file.
+;
+;
+; ***************************************************************************
+
+
+.equ clock=1000000 ; Define the clock frequency
+;.equ clock=8000000 ; Define the clock frequency
+
+
+
+.nolist
+.include "include/tn84def.inc" ; Define device ATtiny84
+.list
+
+.include "../defs.asm"
+.include "./data.asm"
+
+.include "version.asm"
+.include "devices/all/defs.asm"
+.include "common/calls.asm"
+.include "common/utils_io.asm"
+.include "common/utils_wait.asm"
+
+
+
+; ***************************************************************************
+; defines
+
+; ---------------------------------------------------------------------------
+; generic
+
+.equ NET_BUFFERS_NUM            =  6
+.equ NET_MSGNUMINBUF_SIZE       =  8 ; max buffer nums in ringbuffer (global incoming)
+.equ NET_IFACE_OUTMSGBUF_SIZE   =  8 ; max buffer nums in ringbuffer (per interface outbound)
+
+
+
+
+; ---------------------------------------------------------------------------
+; firmware settings including list of modules used
+
+; #define MODULES_TIMER
+#define MODULES_CLOCK
+#define MODULES_LED_SIMPLE
+;#define MODULES_LED_ACTIVITY
+#define MODULES_NETWORK
+;#define MODULES_UART_BITBANG
+#define MODULES_COM2W
+#define MODULES_TWI_MASTER
+;#define MODULES_LCD
+;#define LCD_MINIMAL_FONT
+;#define MODULES_SI7021
+#define MODULES_SGP30
+;#define MODULES_SGP40
+;#define MODULES_STATS
+;#define MODULES_OWI_MASTER
+;#define MODULES_DS18B20
+;#define MODULES_MOTION
+;#define MODULES_CCS811
+;#define MODULES_BRIGHTNESS
+
+#define APPS_NETWORK
+;#define APPS_MOTION
+#define APPS_REPORTSENSORS
+#define APPS_STATS
+
+
+
+; ---------------------------------------------------------------------------
+; defines for values
+
+;.equ VALUE_ID_SGP40_TVOC       = 0x08
+
+.equ VALUE_ID_SGP30_TVOC       = 0x09
+.equ VALUE_ID_SGP30_CO2        = 0x0a
+
+
+
+
+
+; ***************************************************************************
+; code segment
+
+.cseg
+.org 000000
+
+
+
+; ---------------------------------------------------------------------------
+; Reset and interrupt vectors
+
+        rjmp BOOTLOADER_ADDR ; Reset vector  ; use this for flashed system
+	reti ; EXT_INT0
+        rjmp com2wPcintIsr         ; PCI0
+	reti ; PCI1
+	reti ; WATCHDOG
+	reti ; ICP1
+	reti ; OC1A
+	reti ; OC1B
+	reti ; OVF1
+        rjmp baseTimerIrqOC0A ; OC0A
+	reti ; OC0B
+	reti ; OVF0
+	reti ; ACI
+        reti ; ADCC
+	reti ; ERDY
+	reti ; USI_STR
+	reti ; USI_OVF
+
+
+devInfoBlock:        ; 12 bytes
+devInfoManufacturer: .db 'A', 'Q', 'U', 'A'
+devInfoId:           .db DEVICEINFO_ID, 0
+devInfoVersion:      .db DEVICEINFO_VERSION, DEVICEINFO_REVISION             ; version, revision
+firmwareVersion:     .db FIRMWARE_VARIANT_TEMP_WINDOW, FIRMWARE_VERSION_MAJOR
+                     .db FIRMWARE_VERSION_MINOR, FIRMWARE_VERSION_PATCHLEVEL
+
+
+
+; ---------------------------------------------------------------------------
+; @routine firmwareStart @global
+
+firmwareStart:
+  rjmp main
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine onSystemStart
+
+onSystemStart:
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine onMessageReceived
+;
+; Called on every message received
+
+onMessageReceived:
+  clc
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine onEvery100ms
+;
+; Called every 100ms. Add your routine calls here. No arguments, no results.
+
+onEvery100ms:
+onEverySecond:
+onEveryMinute:
+onEveryHour:
+onEveryDay:
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine onEveryLoop
+;
+; Called on every loop (i.e. after awakening from sleep).
+;
+onEveryLoop:
+  ret
+; @end
+
+
+
+
+
+; ***************************************************************************
+; includes
+
+.include "devices/all/hw_tn84.asm"
+.include "devices/all/includes.asm"
+
+
+
+; ---------------------------------------------------------------------------
+; defines for network interface
+
+.equ netInterfaceData = com2w_iface
+
+
+
+deviceCodeEnd:
+  .if deviceCodeEnd >= BOOTLOADER_ADDR
+    .warning "Code reaches into boot loader!"
+  .endif
+
diff --git a/avr/devices/n31/n31-enclosure.stl b/avr/devices/n31/n31-enclosure.stl
new file mode 100644
index 0000000..e9e0de6
Binary files /dev/null and b/avr/devices/n31/n31-enclosure.stl differ
diff --git a/devices/nodes/0BUILD b/devices/nodes/0BUILD
index ef59e2d..3f026b8 100644
--- a/devices/nodes/0BUILD
+++ b/devices/nodes/0BUILD
@@ -27,6 +27,7 @@
     aqua_n28.xml
     aqua_n29.xml
     aqua_n30.xml
+    aqua_n31.xml
     aqua_r05.xml
     aqua_r06.xml
     aqua_s03.xml
diff --git a/devices/nodes/aqua_n31.xml b/devices/nodes/aqua_n31.xml
new file mode 100644
index 0000000..6a1353d
--- /dev/null
+++ b/devices/nodes/aqua_n31.xml
@@ -0,0 +1,12 @@
+
+<device name="aqua_n31" driver="nodes">
+  <manufacturer>AQUA</manufacturer>
+  <devicetype>N</devicetype>
+  <deviceversion>31</deviceversion>
+  
+  <values>
+    <value name="SGP30_TVOC"             id="0x09" type="sensor" dataType="rational" modality="tvoc"  denom="1" />
+    <value name="SGP30_CO2"              id="0x0a" type="sensor" dataType="rational" modality="co2"   denom="1" />
+  </values>
+
+</device>