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STATIC ASSIGNMENT OF BUS IDENTIFIERS AND CORRESPONDING ACCEPTANCE FILTERS FOR CARRIER SENSE MULTIPLE ACCESS / COLLISION RESOLUTION (CSMAICR) NETWORK PROTOCOLS

IP.com Disclosure Number: IPCOM000009087D
Original Publication Date: 1999-Jun-01
Included in the Prior Art Database: 2002-Aug-07
Document File: 3 page(s) / 176K

Publishing Venue

Motorola

Related People

Ivan Gumenyuk: AUTHOR

Abstract

This proposal relates to network communication technology with Carrier Sense Multiple Access/Collision Resolution protocols (CSMAKR), like Controller Area Network (CAN) protocol, Vehicle Area Network (VAN) protocol, High-level Data Link Control (HDLC) protocol, etc. The pro- posed method provides automatic generation of bus identifiers (IDS) for all network messages in a sys- tem as well as the appropriate values of acceptance filters for each network node. This leads to increas- ing system performance. This method can simplify development and reduce the development cycle time.

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MOTOROLA Technical Developments

STATIC ASSIGNMENT OF BUS IDENTIFIERS AND CORRESPONDING ACCEPTANCE FILTERS FOR CARRIER SENSE MULTIPLE ACCESS /

COLLISION RESOLUTION (CSMAICR) NETWORK PROTOCOLS

by Ivan Gumenyuk

INTRODUCTION

  This proposal relates to network communication technology with Carrier Sense Multiple Access/Collision Resolution protocols (CSMAKR), like Controller Area Network (CAN) protocol, Vehicle Area Network (VAN) protocol, High-level Data Link Control (HDLC) protocol, etc. The pro- posed method provides automatic generation of bus identifiers (IDS) for all network messages in a sys- tem as well as the appropriate values of acceptance filters for each network node. This leads to increas- ing system performance. This method can simplify development and reduce the development cycle time.

PROBLEMS TO BE SOLVED

  In networks based on CSMAKR protocols, messages are addressed by unique bus identifiers. Hardware devices have built-in acceptance filters, which specifically accept or reject messages to reduce CPU interventions. The network has a num- ber of separate nodes, and a number of different messages are transferred through the network. Messages can simultaneously be transferred from 1 sender to N receivers (1 :N communication).

  In case of 1:N communication, some nodes can have similar acceptance filter values. Therefore, some nodes can accept messages that are not desig- nated for them. It requires additional software for checking and decreases the overall system perfor- mance ("false alarms" cases). The number of "false alarms" should be reduced to the minimum to pro- vide the best performance of the system.

PROPOSED SOLUTION

  Network message bus IDS and hardware accep- tance filters are automatically and uniquely assigned to corresponding messages for particular nodes (at system generation stage). This is the static assign- ment that cannot be changed at run time.

1. Bus Identifier Structure Separate identifications for network messages and network nodes within the bus identifier are used. The bus ID has two fields (Figure 1): Message Identifier (MI) for message addressing and Node Prefix (NP) for node addressing.

  MI occupies the MSBs of the bus ID and NP occupies the LSBs. Such field allocation provides proper bus message prioritization. The field length equals the number of bits needed to binary present the input value:

LMI = [logz(NM)]
L.NP = [log2(NN)]

(1)

m

where NM is the total number of network messages and NN is the total number of network stations (nodes). If LMI + LNP is smaller than the number of bits in the bus identifier, then unused bits remain in the middle of a bus ID as presented in PIG. 1. These remaining bits can be used for additional opti- mization of bus IDS, to reduce the number of "false alarms" on network nodes (see below in section 2). These bits can be used as additional bits for node addressing. Acceptance filter registers are also con- sidered as consisting of these fields.

2. Assignment of Bus...