<s>
TTP/A	B-Application
is	O
a	O
time-triggered	O
real-time	B-General_Concept
fieldbus	O
protocol	O
used	O
for	O
the	O
interconnection	O
of	O
low-cost	O
smart	B-Algorithm
transducer	I-Algorithm
nodes	O
.	O
</s>
<s>
In	O
contrast	O
to	O
the	O
Time-Triggered	O
Protocol	O
(	O
TTP	O
)	O
,	O
which	O
is	O
a	O
high-speed	O
,	O
fault-tolerant	O
communication	O
network	O
intended	O
for	O
safety	O
critical	O
applications	O
(	O
SAE	O
class	O
C	O
)	O
,	O
TTP/A	B-Application
provides	O
a	O
low-speed	O
(	O
below	O
1	O
MB/s	O
)	O
,	O
low-cost	O
protocol	O
suitable	O
for	O
non-critical	O
applications	O
like	O
car	O
body	O
electronics	O
(	O
SAE	O
class	O
A	O
)	O
.	O
</s>
<s>
The	O
TTP/A	B-Application
protocol	O
implements	O
a	O
communication	O
layer	O
and	O
data	O
access	O
according	O
to	O
the	O
Object	B-Architecture
Management	I-Architecture
Group	I-Architecture
smart	B-Algorithm
transducer	I-Algorithm
Interface	O
standard	O
which	O
was	O
published	O
in	O
late	O
2002	O
.	O
</s>
<s>
The	O
interface	O
to	O
each	O
transducer	O
is	O
known	O
as	O
an	O
Interface	O
File	O
System	O
(	O
IFS	O
)	O
,	O
that	O
includes	O
both	O
real-time	B-General_Concept
data	I-General_Concept
,	O
as	O
well	O
as	O
configuration	O
and	O
node	O
management	O
features	O
.	O
</s>
<s>
The	O
IFS	O
makes	O
it	O
possible	O
to	O
share	O
data	O
between	O
different	O
TTP/A	B-Application
clusters	O
in	O
a	O
transparent	O
fashion	O
,	O
so	O
that	O
for	O
the	O
application	O
no	O
distinction	O
between	O
data	O
from	O
local	O
and	O
remote	O
nodes	O
is	O
made	O
.	O
</s>
<s>
The	O
TTP/A	B-Application
protocol	O
does	O
not	O
require	O
special	O
controller	O
hardware	O
and	O
can	O
be	O
implemented	O
on	O
any	O
standard	O
embedded	O
microcontroller	O
.	O
</s>
<s>
An	O
open-source	O
implementation	O
exists	O
for	O
the	O
Atmel	B-Architecture
AVR	I-Architecture
architecture	O
.	O
</s>
<s>
Like	O
the	O
fault-tolerant	O
time-triggered	O
protocol	O
TTP	O
,	O
TTP/A	B-Application
follows	O
the	O
time-triggered	O
paradigm	O
featuring	O
a	O
clock	O
synchronization	O
and	O
predefined	O
time-triggered	O
schedules	O
for	O
communication	O
and	O
execution	O
of	O
tasks	O
.	O
</s>
<s>
Thus	O
,	O
TTP/A	B-Application
communication	O
implements	O
a	O
strict	O
time	O
division	O
multiple	O
access	O
(	O
TDMA	O
)	O
scheduling	O
.	O
</s>
<s>
TTP/A	B-Application
can	O
be	O
used	O
as	O
a	O
sub-bus	O
for	O
a	O
higher-performance	O
and	O
more	O
dependable	O
real-time	B-General_Concept
systems	O
,	O
or	O
to	O
provide	O
transducer	O
data	O
to	O
a	O
Linux	B-Application
system	O
in	O
a	O
soft-real-time	O
fashion	O
.	O
</s>
<s>
TTP/A	B-Application
was	O
used	O
in	O
applications	O
such	O
as	O
an	O
intercommunication	O
system	O
for	O
mobile	O
robots	O
.	O
</s>
<s>
TTP/A	B-Application
is	O
a	O
time-triggered	O
protocol	O
used	O
for	O
the	O
communication	O
of	O
one	O
active	O
master	O
with	O
or	O
among	O
smart	B-Algorithm
transducer	I-Algorithm
nodes	O
within	O
a	O
cluster	O
.	O
</s>
<s>
TTP/A	B-Application
communication	O
is	O
organized	O
into	O
rounds	O
separated	O
by	O
inter	O
round	O
gaps	O
(	O
IRG	O
)	O
.	O
</s>
<s>
The	O
TTP/A	B-Application
bus	O
is	O
inactive	O
for	O
at	O
least	O
13	O
bit	O
times	O
during	O
each	O
gap	O
.	O
</s>
<s>
A	O
TTP/A	B-Application
round	O
consists	O
of	O
one	O
or	O
more	O
frames	O
.	O
</s>
<s>
Several	O
papers	O
were	O
published	O
by	O
researchers	O
at	O
the	O
Vienna	O
University	O
of	O
Technology	O
on	O
TTP/A	B-Application
from	O
1994	O
through	O
2006	O
by	O
Hermann	O
Kopetz	O
and	O
Wilfried	O
Elmenreich	O
.	O
</s>
