Intra-vehicular LAN and method of routing messages along it using hash functions

• US 5,701,418 A
• Filed: 03/31/1994
• Issued: 12/23/1997
• Est. Priority Date: 03/31/1994
• Status: Expired due to Term

• Current Assignee: Chrysler Group LLC (Stellantis NV)
• Original Assignee: Chrysler Corporation (Stellantis NV)
• Inventors: Luitje, William V.
• Primary Examiner(s): Geckil, Mehmet B.
• Application Number:
  US08/221,822
• Time in Patent Office: 1,363 Days
• Field of Search: 395/200.02, 395/200.15, 395/200.16, 395/200.1, 395/828, 395/829, 395/830, 395/849, 395/412, 395/414, 395/415, 395/421.03, 395/421.05, 395/421.06, 395/421.11, 395/416, 395/417, 364/131, 364/147, 364/424.01, 364/424.05, 364/425
• US Class Current: 709/245
• CPC Class Codes: B60R 16/0315 using multiplexing techniques multiplexing for transmission of signals G08C15/00; multiplexing for electrical communication in general H04J
• CPC Class Codes: H04L 45/745 Address table lookup; Address filtering

Abstract

Microcontrollers, e.g. those located within a vehicle or factory, are connected over a local area network (LAN). The microcontrollers broadcast messages on the LAN tagged with an identifier (ID) which identifies the contents of the message, rather than a destination address. Microcontrollers on the network are provided with read only memory (ROM) containing a table of message IDs and accompanying data, wherein the table address of each message ID was initially determined by applying a hash function to the ID. Upon receipt of a message, a microcontroller applies the hash function to the message ID. Using the result as a pointer into the table, the microcontroller compares the message ID stored in that pointer location with the received message ID. If they are equal, the microcontroller performs a predetermined function. If the message IDs are not equal, the message is ignored.

Claims

1. A control system comprising:

at least two microcontrollers for processing information to control parts of the system, each said microcontroller generating messages while processing the information which are related to the status of said controlled parts and receiving messages related to the status of said controlled parts of the system controlled by another microcontroller, each such message being identified with a message identifier;

memory means associated with each microcontroller, said memory means storing a table of message identifiers which the associated microcontroller is capable of processing and related instructions for processing the message;

a local area network connecting said at least two microcontrollers, said local area network transmitting messages to all said at least two controllers; and

means at each microcontroller for applying a hash function to the identifier of each message received over the local area network in order to generate a table index which directs the microcontroller to a particular entry in the table stored in the memory means, comparing the message identifier at the particular entry to the message identifier of the message received, and causing the microcontroller to respond to the message if the identifiers match.

2. The control system of claim 1 wherein the at least two microcontrollers and the local area network form an intra-vehicular control system for a vehicle.

3. The control system of claim 1 wherein the hash function is a linear congruential hash function.

4. The control system of claim 2 wherein the hash function is a linear congruential hash function.

5. The control system of claim 1 wherein the hash function is a multiplicative exclusive OR hash function.

6. The control system of claim 2 wherein the hash function is a multiplicative exclusive OR hash function.

7. The control system of claim 1 wherein the hash function is a reciprocal hash function.

8. The control system of claim 2 wherein the hash function is a reciprocal hash function.

9. The control system of claim 1 wherein the microcontrollers are programmed microprocessors.

10. In a microprocessor-based local area network, a method by which a first microprocessor on the network determines whether a message with a message identifier broadcast on the network by a second microprocessor on the network is one to which said first microprocessor must respond, the first microcontroller having memory, the memory storing a hash table of message identifiers and related information at each microprocessor on the network, the method comprising:

examining said broadcast message for said identifier;

determining a hash table index by applying a predefined hash function to said identifier;

using said hash table index to determine a location within said hash table;

comparing an entry stored in said hash location with said message identifier; and

performing a predetermined function if said entry and said message identifier are the same.

11. The method of claim 10 wherein the network is an intra-vehicular local area network which controls operation of a vehicle.

12. The method of claim 10 wherein said hash function is a linear congruential hash function.

13. The method of claim 10 wherein the network is an intra-vehicular local area network which controls operation of a vehicle.

14. The method of claim 10 wherein said hash function is a Multiplicative XOR function.

15. The method of claim 10 wherein the network is an intra-vehicular local area network which controls operation of a vehicle.

16. The method of claim 10 wherein said hash function reciprocal hash function.

17. The method of claim 10 wherein the network is an intra-vehicular local area network which controls operation of a vehicle.