<s>
Ethernut	B-Application
is	O
an	O
open	O
source	O
hardware	O
and	O
software	O
project	O
for	O
use	O
as	O
an	O
embedded-Ethernet-system	O
.	O
</s>
<s>
Currently	O
four	O
different	O
reference	O
designs	O
exist	O
(	O
Ethernut	B-Application
1	O
,	O
Ethernut	B-Application
2	O
,	O
Ethernut	B-Application
3	O
and	O
Ethernut	B-Application
5	O
)	O
which	O
are	O
available	O
as	O
ready	O
to	O
use	O
boards	O
.	O
</s>
<s>
The	O
designs	O
mainly	O
differ	O
in	O
the	O
used	O
microcontroller	B-Architecture
(	O
Ethernut	B-Application
1	O
&	O
2	O
:	O
8-bit	O
AVR	B-Architecture
,	O
Ethernut	B-Application
3	O
&	O
5	O
:	O
32-bit	O
ARM	B-Architecture
)	O
and	O
the	O
available	O
memory	O
size	O
.	O
</s>
<s>
Since	O
the	O
Ethernut	B-Application
3	O
board	O
an	O
MMC	O
slot	O
is	O
available	O
.	O
</s>
<s>
Ethernut	B-Application
5	O
also	O
includes	O
USB	B-Protocol
host	O
and	O
device	O
interfaces	O
.	O
</s>
<s>
With	O
the	O
rise	O
of	O
the	O
idea	O
of	O
the	B-Operating_System
Internet	I-Operating_System
of	I-Operating_System
Things	I-Operating_System
,	O
different	O
groups	O
of	O
people	O
with	O
different	O
aims	O
started	O
around	O
2000	O
developing	O
embedded	B-Architecture
systems	I-Architecture
which	O
would	O
be	O
able	O
to	O
integrate	O
in	O
existing	O
TCP/IP	B-Protocol
networks	I-Protocol
.	O
</s>
<s>
The	O
limited	O
resources	O
of	O
this	O
mostly	O
8-bit	O
embedded	B-Architecture
systems	I-Architecture
,	O
which	O
rarely	O
reached	O
or	O
exceeded	O
64	O
kB	O
of	O
main	O
memory	O
,	O
imposed	O
a	O
great	O
challenge	O
.	O
</s>
<s>
In	O
the	O
year	O
2000	O
the	O
British	O
developer	O
Dave	O
Hudson	O
released	O
the	O
source	O
code	O
of	O
a	O
real-time	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
with	O
integrated	O
TCP/IP	B-Protocol
stack	I-Protocol
named	O
Liquorice	O
.	O
</s>
<s>
Nearly	O
all	O
network	O
controllers	O
of	O
that	O
time	O
used	O
the	O
PCI-Bus	B-Protocol
interface	O
which	O
is	O
too	O
complex	O
for	O
small	O
microcontrollers	B-Architecture
.	O
</s>
<s>
But	O
one	O
of	O
the	O
few	O
still-in-production	O
controllers	O
with	O
ISA-Bus	B-Architecture
interface	O
,	O
which	O
also	O
was	O
not	O
recommended	O
for	O
new	O
designs	O
,	O
was	O
used	O
together	O
with	O
ATmega103	O
microcontroller	B-Architecture
to	O
create	O
a	O
single	O
board	O
computer	O
.	O
</s>
<s>
The	O
layout	O
of	O
this	O
board	O
was	O
released	O
under	O
BSD	B-Operating_System
license	I-Operating_System
and	O
was	O
one	O
of	O
the	O
early	O
open	O
hardware	O
projects	O
.	O
</s>
<s>
But	O
the	O
source	O
code	O
of	O
Liquorice	O
was	O
used	O
as	O
software	O
foundation	O
for	O
the	O
new	O
Ethernut	B-Application
project	O
which	O
aimed	O
to	O
integrate	O
software	O
and	O
hardware	O
development	O
.	O
</s>
<s>
After	O
the	O
first	O
few	O
versions	O
had	O
been	O
released	O
to	O
the	O
AVR	B-Architecture
Freaks	O
Board	O
,	O
the	O
project	O
switched	O
to	O
SourceForge	O
in	O
2002	O
.	O
</s>
<s>
The	O
open	O
source	O
operating	B-General_Concept
system	I-General_Concept
for	O
these	O
boards	O
is	O
called	O
Nut/OS	O
.	O
</s>
<s>
It	O
is	O
a	O
modular	O
real-time	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
,	O
licensed	O
under	O
BSD	B-Operating_System
license	I-Operating_System
.	O
</s>
<s>
Nut/OS	O
is	O
supported	O
by	O
popular	O
SSL/TLS	B-Protocol
libraries	O
such	O
as	O
wolfSSL	B-Protocol
for	O
embedded	B-Architecture
security	O
.	O
</s>
<s>
The	O
Ethernut	B-Application
project	O
implements	O
its	O
own	O
network	O
stack	O
,	O
called	O
Nut/Net	O
.	O
</s>
<s>
Beside	O
of	O
the	O
Nut/OS	O
libraries	O
the	O
application	O
programmer	O
can	O
use	O
the	O
standard	B-Language
C	I-Language
libraries	I-Language
.	O
</s>
<s>
As	O
programming	O
languages	O
C	B-Language
is	O
used	O
,	O
but	O
C++	B-Language
is	O
mostly	O
supported	O
as	O
well	O
.	O
</s>
<s>
Additionally	O
a	O
Lua	B-Language
interpreter	B-Application
exists	O
so	O
that	O
Lua	B-Language
scripts	I-Language
can	O
be	O
executed	O
interactively	O
at	O
runtime	O
on	O
the	O
board	O
.	O
</s>
<s>
Atmel	B-Architecture
AVR	I-Architecture
(	O
e.g.	O
</s>
<s>
:	O
ATmega103	O
,	O
ATmega128	O
,	O
ATmega2561	B-Architecture
,	O
AT90CAN128	O
,	O
etc	O
.	O
)	O
</s>
<s>
Atmel	B-Device
AVR32	I-Device
(	O
e.g.	O
</s>
<s>
:	O
AT91R40008	O
,	O
AT91SAM7X	O
,	O
LPC-E2294	O
,	O
Game	B-Device
Boy	I-Device
Advance	I-Device
,	O
etc	O
.	O
)	O
</s>
<s>
The	O
following	O
architectures	B-General_Concept
are	O
supported	O
but	O
not	O
actively	O
maintained	O
:	O
</s>
<s>
The	O
research	O
group	O
for	O
distributed	O
systems	O
of	O
the	O
ETH	O
Zurich	O
has	O
developed	O
a	O
distributed	B-Architecture
Sensor	I-Architecture
network	I-Architecture
with	O
nodes	O
based	O
on	O
AVR	B-Architecture
.	O
</s>
<s>
These	O
sensor	B-Device
nodes	I-Device
communicate	O
via	O
Bluetooth	B-Protocol
.	O
</s>
<s>
As	O
system	O
software	O
the	O
open	O
source	O
BTNut	O
Bluetooth	B-Protocol
stack	O
is	O
used	O
.	O
</s>
<s>
The	O
BTNut	O
stack	O
is	O
based	O
on	O
the	O
Nut/OS	O
system	O
and	O
extends	O
the	O
Nut/OS	O
functionality	O
with	O
Bluetooth	B-Protocol
access	O
functions	O
.	O
</s>
<s>
Although	O
the	O
BTNut	O
stack	O
was	O
developed	O
mainly	O
for	O
the	O
BTNode	O
sensor	B-Device
nodes	I-Device
it	O
can	O
be	O
easily	O
ported	O
to	O
other	O
applications	O
.	O
</s>
<s>
According	O
to	O
the	O
German	O
manufacturer	O
(	O
egnite	O
GmbH	O
)	O
about	O
33.000	O
Ethernut	B-Application
boards	O
were	O
sold	O
(	O
state	O
:	O
December	O
2013	O
)	O
.	O
</s>
<s>
(	O
Czech	O
Republic	O
)	O
,	O
thermotemp	O
Embedded-IT	O
(	O
Germany	O
)	O
.	O
</s>
<s>
Beside	O
these	O
,	O
the	O
Nut/OS	O
operating	B-General_Concept
system	I-General_Concept
is	O
used	O
as	O
base	O
for	O
the	O
BTNode	O
Sensor	B-Architecture
network	I-Architecture
ETH	O
Zurich	O
.	O
</s>
