AS8205
TTP/C-C2XNF StarCoupler – Preliminary Data Sheet
3 Key Features
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Dedicated busguardian supporting TTP/C (time triggered protocol class C)
Suited for dependable distributed real-time systems with guaranteed response time
Application fields: Automotive (by-wire braking, steering, vehicle dynamics control, drive
train control), Aerospace (aircraft electronic systems), Industrial systems, Railway systems
TTP/C asynchronous data rate up to 5 MBit/s @ clock 40 MHz
Single power supply 3.3V
0.35µm CMOS process
Temperature range: -40°C to 125° C
16 Ports for serial communication with TTP/C nodes
per port configurable encoding: MFM/Manchester
Signal reshaping to avoid byzantine scenarios
2k x 16 SRAM for message, status and control area (communication network interface)
8k x 16 SRAM for MEDL configuration data (MEDL can be decreased in steps of 2k x 16 to
get more CNI RAM)
4k x 16 SRAM for instruction code and configuration data
4k x 16 Boot ROM
16 Bit non-multiplexed host CPU interface
16 Bit RISC architecture
software tools, design-in support, development boards available (
http://www.tttech.com/
)
120 pin LQFP Package, body size 14 x 14mm, 0.4mm pitch
4 General Description
The AS8205 starcoupler is an integrated device supporting serial communication according to
the TTP/C specification. It performs all communication tasks such as reception and transmis-
sion of messages in a TTP
cluster without interaction of a host CPU.
TTP
provides mechanisms that allow the deployment of high-dependability distributed real-
time systems. It provides following services:
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predictable transmission of messages with minimal jitter
fault-tolerant distributed clock synchronisation
consistent membership service with small delay
masking of single faults
The Task of the Central Busguardian as an independent unit is to isolate faulty nodes (e.g.
babbling idiots) from the cluster. The Central Busguardian provides writeaccess to the shared
medium to every node according to the timing information stored in the SWIDL (Switch descrip-
tor list). This ensures that each connected node only sends in its own timeslot. The SWIDL is
generated from the TTTech-toolchain like the MEDL during clusterdesign. The Central Bus-
guardian has an integrated TTP/C controller (C2NF) to perform tasks like global time synchro-
nisation, membership calculation, integration during systemstartup, integration into a running
cluster, etc. Another task of the Central Busguardian is to make sure that every connected
node gets the same information to avoid byzantine scenarios. Therefore it decodes the incom-
ing signal and encodes it again (reshape-unit). This reshaped signal is then provided to all other
nodes.
Rev. 1.0, September 2002
uncontrolled copy
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