TTP-C2NF Communication Controller – Data Sheet

AS8202NF

Rev. 1.7, Copyright 2000-2007, austriamicrosystems AG and TTChip Entwicklungsgesellschaft mbH. All rights reserved.

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1 . Ge n e r a l D e s c r i p t i o n

The AS8202NF communication controller is an integrated device supporting serial

tasks such as reception and transmission of messages in a TTP cluster without interaction of

the host CPU. TTP provides mechanisms that allow the deployment in high-dependability

distributed real-time systems. It provides the following services:

• Predictable transmission of messages with minimal jitter

• Fault-tolerant distributed clock synchronization

• Consistent membership service with small delay

• Masking of single faults

The CNI (communication network interface) forms a temporal firewall. It decouples the

controller network from the host subsystem by use of a dual ported RAM (CNI). This prevents

the propagation of control errors. The interface to the host CPU is implemented as a 16-bit wide

non-multiplexed asynchronous bus interface.

TTP follows a conflict-free media access strategy called time division multiple access (TDMA).

This means, TTP deploys a time slot technique based on a global time that is permanently

synchronized. Each node is assigned a time slot in which it is allowed to perform transmit

operation. The sequence of time slots is called TDMA round, a set of TDMA rounds forms a

cluster cycle. The operation of the network is repeated after one cluster cycle. The sequence of

interactions forming the cluster cycle is defined in a static time schedule, called message

descriptor list (MEDL). The definition of the MEDL in conjunction with the global time

determines the response time for a service request.

The membership of all nodes in the network is evaluated by the communications controller.

This information is presented to all correct cluster members in a consistent fashion. During

operation, the status of all other nodes is propagated within one TDMA round. Please read

RXD[1:0]

RXCLK[1:0]

RXDV[1:0]

RXER[1:0]

XIN1

XOUT1

TXD[1:0]

CTS[1:0]

TXCLK[1:0]

RAM_CLK

_TESTSE

FTEST

STEST

FIDIS

TTEST

D[15:0]

A[11:0]

CEB

OEB

WEB

READYB

INTB

LED[2:0]

RAM_CLK_TESTSE

USE_RAM_CLK

XIN0

XOUT0

PLLOFF

RESETB

Quartz or

Oscillator

Communi-

cation

network

interface

(CNI)

---------------------

Network

configuration

memory

(MEDL)

TTP

protocol

processor core

Instruction

memory

RAM & ROM

Test

Interface

TTP Bus

Media

Drivers

Bus

guardian

Receiver

Transmitter

Reset & time

base

Host

Processor

Interface

Test

Inter-

face

Figure 1. AS8202NF Block Diagram