<s>
Cyphal	B-Protocol
is	O
a	O
lightweight	O
protocol	O
designed	O
for	O
reliable	O
intra-vehicle	O
communications	O
using	O
various	O
communications	O
transports	O
,	O
originally	O
destined	O
for	O
CAN	B-Protocol
bus	I-Protocol
,	O
but	O
targeting	O
various	O
network	O
types	O
in	O
subsequent	O
revisions	O
.	O
</s>
<s>
OpenCyphal	B-Protocol
is	O
an	O
open-source	O
project	O
that	O
aims	O
to	O
provide	O
MIT-licensed	O
implementations	O
of	O
the	O
Cyphal	B-Protocol
protocol	O
.	O
</s>
<s>
The	O
project	O
was	O
known	O
as	O
UAVCAN	B-Protocol
(	O
Uncomplicated	O
Application-level	O
Vehicular	O
Computing	O
and	O
Networking	O
)	O
prior	O
to	O
rebranding	O
in	O
March	O
2022	O
.	O
</s>
<s>
The	O
first	O
RFC	O
broadly	O
outlining	O
the	O
general	O
ideas	O
that	O
would	O
later	O
form	O
the	O
core	O
design	O
principles	O
of	O
Cyphal	B-Protocol
(	O
branded	O
UAVCAN	B-Protocol
at	O
the	O
time	O
)	O
was	O
published	O
in	O
early	O
2014	O
.	O
</s>
<s>
Since	O
the	O
original	O
RFC	O
,	O
the	O
protocol	O
has	O
been	O
through	O
three	O
major	O
design	O
iterations	O
,	O
which	O
culminated	O
in	O
the	O
release	O
of	O
the	O
first	O
long-term	O
stable	O
revision	O
in	O
2020	O
(	O
6	O
years	O
later	O
)	O
labelled	O
UAVCAN	B-Protocol
v1.0	O
.	O
</s>
<s>
In	O
2022	O
,	O
the	O
protocol	O
was	O
rebranded	O
as	O
Cyphal	B-Protocol
.	O
</s>
<s>
Cyphal	B-Protocol
is	O
positioned	O
by	O
its	O
developers	O
as	O
a	O
highly	O
deterministic	O
,	O
safety-oriented	O
alternative	O
to	O
high-level	O
publish-subscribe	O
frameworks	O
such	O
as	O
DDS	B-Application
or	O
the	O
computation	O
graph	O
of	O
ROS	O
,	O
which	O
is	O
sufficiently	O
compact	O
and	O
simple	O
to	O
be	O
usable	O
in	O
deeply	O
embedded	O
high-integrity	O
applications	O
.	O
</s>
<s>
Cyphal	B-Protocol
has	O
been	O
shown	O
to	O
be	O
usable	O
with	O
bare	O
metal	O
microcontrollers	O
equipped	O
with	O
as	O
little	O
as	O
32K	O
ROM	O
and	O
8K	O
RAM	O
.	O
</s>
<s>
a	O
.	O
MODBUS	B-Protocol
often	O
runs	O
over	O
RS-232	O
.	O
</s>
<s>
b	O
.	O
DDS	B-Application
Borrows	O
an	O
Interface	B-General_Concept
Definition	I-General_Concept
Language	I-General_Concept
from	O
CORBA	O
.	O
</s>
<s>
c	O
.	O
MODBUS	B-Protocol
over	O
TCP	O
port	O
502	O
.	O
</s>
<s>
e	O
.	O
First	O
AVB	B-Protocol
standard	O
is	O
published	O
by	O
the	O
AVB	B-Protocol
Task	O
Group	O
of	O
the	O
IEEE	O
802.1	O
working	O
group	O
.	O
</s>
<s>
f	O
.	O
The	O
AVB	B-Protocol
Task	O
Group	O
is	O
renamed	O
the	O
TSN	O
Task	O
Group	O
.	O
</s>
<s>
g	O
.	O
ROS2	O
Builds	O
on	O
top	O
of	O
DDS	B-Application
.	O
</s>
<s>
i	O
.	O
Pavel	O
Kirienko	O
leads	O
an	O
open-source	O
effort	O
to	O
define	O
UAVCAN	B-Protocol
v0	O
.	O
</s>
<s>
j	O
.	O
Airbus	O
gives	O
a	O
presentation	O
to	O
the	O
IEEE	O
,	O
“	O
Avionics	O
Full	O
Duplex	O
Ethernet	O
and	O
the	O
Time-Sensitive	B-Protocol
Networking	I-Protocol
Standard	O
”	O
which	O
proposes	O
incorporating	O
AFDX	B-Protocol
into	O
the	O
TSN	O
standards	O
.	O
</s>
<s>
At	O
the	O
same	O
time	O
,	O
at	O
the	O
Stockholm	O
Summit	O
,	O
UAVCAN	B-Protocol
v1	O
was	O
conceived	O
.	O
</s>
<s>
MODBUS	B-Protocol
replacement	O
)	O
.	O
</s>
<s>
o	O
.	O
UAVCAN	B-Protocol
v1	O
becomes	O
beta	O
.	O
</s>
<s>
p	O
.	O
DroneCAN	O
takes	O
over	O
maintenance	O
of	O
the	O
UAVCAN	B-Protocol
v0/v0.5	O
specification	O
and	O
advancement	O
on	O
top	O
of	O
it	O
.	O
</s>
<s>
q	O
.	O
UAVCAN	B-Protocol
v1	O
is	O
renamed	O
Cyphal	B-Protocol
.	O
</s>
<s>
Cyphal	B-Protocol
provides	O
zero-cost	O
abstractions	O
that	O
are	O
approachable	O
and	O
familiar	O
to	O
software	O
engineers	O
without	O
compromising	O
on	O
functional	O
safety	O
and	O
determinism	O
.	O
</s>
<s>
As	O
a	O
new	O
technology	O
,	O
it	O
is	O
unencumbered	O
by	O
legacy	O
and	O
borrows	O
heavily	O
from	O
recent	O
developments	O
in	O
the	O
field	O
of	O
general	O
information	B-General_Concept
technology	I-General_Concept
.	O
</s>
<s>
DSDL	O
is	O
ideologically	O
similar	O
to	O
the	O
interface	B-General_Concept
description	I-General_Concept
language	I-General_Concept
used	O
in	O
ROS	O
,	O
except	O
that	O
it	O
introduces	O
additional	O
static	O
constraints	O
in	O
order	O
to	O
render	O
the	O
solution	O
suitable	O
for	O
real-time	O
high-integrity	O
embedded	O
systems	O
.	O
</s>
<s>
The	O
similarity	O
prompted	O
some	O
developers	O
to	O
interface	O
ROS	O
with	O
Cyphal	B-Protocol
using	O
automated	O
translation	O
layers	O
.	O
</s>
<s>
Facilitation	O
of	O
functional	O
safety	O
—	O
Cyphal	B-Protocol
system	O
designers	O
have	O
the	O
necessary	O
guarantees	O
and	O
tools	O
at	O
their	O
disposal	O
to	O
analyze	O
the	O
system	O
and	O
ensure	O
its	O
correct	O
behavior	O
.	O
</s>
<s>
The	O
data	O
types	O
used	O
for	O
communication	O
are	O
defined	O
in	O
a	O
clear	O
and	O
platform-agnostic	B-Operating_System
way	O
,	O
that	O
can	O
be	O
easily	O
understood	O
by	O
both	O
machines	O
and	O
humans	O
.	O
</s>
<s>
Facilitation	O
of	O
cross-vendor	O
interoperability	O
—	O
Cyphal	B-Protocol
provides	O
a	O
common	O
foundation	O
that	O
different	O
vendors	O
can	O
build	O
upon	O
to	O
ensure	O
that	O
their	O
equipment	O
is	O
interoperable	O
.	O
</s>
<s>
Cyphal	B-Protocol
provides	O
a	O
generic	O
set	O
of	O
standard	O
application-agnostic	O
communication	O
data	O
types	O
.	O
</s>
<s>
Well-defined	O
generic	O
high-level	O
functions	O
—	O
Cyphal	B-Protocol
defines	O
standard	O
services	O
and	O
messages	O
for	O
common	O
high-level	O
functions	O
,	O
such	O
as	O
:	O
network	O
discovery	O
,	O
node	O
configuration	O
,	O
node	O
software	O
update	O
,	O
node	O
status	O
monitoring	O
,	O
network-wide	O
time	O
synchronization	O
,	O
plug-and-play	O
node	O
support	O
,	O
etc	O
.	O
</s>
<s>
Cyphal	B-Protocol
performs	O
automatic	O
data	O
decomposition	O
and	O
reassembly	O
at	O
the	O
protocol	O
level	O
,	O
hiding	O
the	O
related	O
complexity	O
from	O
the	O
application	O
.	O
</s>
<s>
High	O
throughput	O
,	O
low	O
latency	O
,	O
determinism	O
—	O
Cyphal	B-Protocol
adds	O
very	O
low	O
overhead	O
to	O
the	O
underlying	O
transport	O
protocol	O
,	O
which	O
ensures	O
high	O
throughput	O
and	O
low	O
latency	O
.	O
</s>
<s>
This	O
makes	O
Cyphal	B-Protocol
well-suited	O
for	O
hard	O
real-time	O
applications	O
.	O
</s>
<s>
Support	O
for	O
redundant	O
interfaces	O
and	O
redundant	O
nodes	O
—	O
Cyphal	B-Protocol
is	O
suitable	O
for	O
applications	O
that	O
require	O
modular	O
redundancy	O
.	O
</s>
<s>
Simple	O
logic	O
,	O
low	O
computational	O
requirements	O
—	O
Cyphal	B-Protocol
targets	O
a	O
wide	O
variety	O
of	O
embedded	O
systems	O
,	O
from	O
high-performance	O
on-board	O
computers	O
,	O
to	O
extremely	O
resource-constrained	O
microcontrollers	O
.	O
</s>
<s>
Rich	O
data	O
type	O
and	O
interface	O
abstractions	O
—	O
An	O
interface	B-General_Concept
description	I-General_Concept
language	I-General_Concept
is	O
a	O
core	O
part	O
of	O
the	O
technology	O
,	O
allowing	O
deeply	O
embedded	O
subsystems	O
to	O
interface	O
with	O
higher-level	O
systems	O
directly	O
(	O
and	O
in	O
a	O
maintainable	O
manner	O
)	O
,	O
while	O
enabling	O
simulation	O
and	O
functional	O
testing	O
.	O
</s>
<s>
Support	O
for	O
various	O
transport	O
protocols	O
—	O
Cyphal	B-Protocol
is	O
usable	O
with	O
several	O
different	O
transports	O
,	O
and	O
can	O
be	O
extended	O
to	O
support	O
other	O
transport	O
protocols	O
in	O
the	O
future	O
.	O
</s>
<s>
API-agnostic	O
standard	O
—	O
Unlike	O
some	O
other	O
networking	O
standards	O
,	O
Cyphal	B-Protocol
does	O
not	O
attempt	O
to	O
describe	O
the	O
application	O
program	O
interface	O
(	O
API	O
)	O
.	O
</s>
<s>
Open	O
specification	O
and	O
reference	O
implementations	O
—	O
The	O
Cyphal	B-Protocol
specification	O
is	O
,	O
and	O
will	O
always	O
be	O
,	O
open	O
and	O
free	O
to	O
use	O
for	O
everyone	O
.	O
</s>
<s>
The	O
reference	O
implementations	O
are	O
distributed	O
under	O
the	O
terms	O
of	O
the	O
permissive	O
MIT	B-License
License	I-License
or	O
released	O
into	O
the	O
public	O
domain	O
.	O
</s>
<s>
The	O
Cyphal/UDP	O
transport	O
has	O
been	O
proposed	O
for	O
real-time	O
Ethernet-based	O
vehicular	O
networks	O
.	O
</s>
<s>
The	O
design	O
is	O
said	O
to	O
be	O
influenced	O
by	O
AFDX	B-Protocol
,	O
DDS/RTPS	O
,	O
and	O
SOME/IP	O
.	O
</s>
<s>
Like	O
other	O
similar	O
technologies	O
,	O
Cyphal	B-Protocol
provides	O
a	O
library	O
of	O
common	O
data	O
types	O
,	O
managed	O
and	O
curated	O
by	O
the	O
protocol	O
maintainers	O
,	O
that	O
are	O
intended	O
to	O
address	O
certain	O
common	O
issues	O
in	O
popular	O
applications	O
.	O
</s>
<s>
These	O
data	O
types	O
supplement	O
vendor-specific	O
or	O
application-specific	O
data	O
types	O
defined	O
by	O
adopters	O
,	O
much	O
like	O
a	O
programming	O
language	O
would	O
normally	O
define	O
a	O
standard	B-Library
library	I-Library
to	O
be	O
relied	O
upon	O
by	O
software	O
developed	O
by	O
the	O
user	O
.	O
</s>
