Browse Prior Art Database

Agile Data Link Interface

IP.com Disclosure Number: IPCOM000037066D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 3 page(s) / 27K

Publishing Venue

IBM

Related People

Goldberg, WD: AUTHOR [+2]

Abstract

This article describes a method and hardware to control a receiver/transmitter on an automotive vehicle interface bus, to set thresholds and drive levels and to analyze results for the purpose of compensation and fault determination. In addition, use of the technique presented herein provides flexibility and adaptability to future communication schemes.

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Agile Data Link Interface

This article describes a method and hardware to control a receiver/transmitter on an automotive vehicle interface bus, to set thresholds and drive levels and to analyze results for the purpose of compensation and fault determination. In addition, use of the technique presented herein provides flexibility and adaptability to future communication schemes.

Conventionally, automotive diagnostic terminal assembly line data link (ALDL) data is presented to an analog receiver 1, as shown in Fig. 1, at some voltage level from 2 and compared with a fixed known value at point 3. The result of this comparison is presented to the local microprocessor 4 as the received data from the vehicle. This approach is vulnerable to a multiplicity of variables. It is a well-established fact that the longer a vehicle is in the field, the less predictable the electrical connections become, due mainly to corrosion. As corrosion takes place, the levels that were specified at the time of manufacture may no longer apply. This phenomenon alone can render the diagnostic tester's ALDL interface inoperative. The agile data link interface disclosed herein performs the function of providing a means whereby application microcode can achieve a significant improvement in control and diagnostic analysis capability.

Fig. 2 is a block diagram of the circuit of the agile data link interface of this disclosure. It includes a high speed differential line receiver 10, dual digital-to- analog (D/A) converters 11A and 11B and a programmable line driver 12.

(Image Omitted)

To establish communication in a system where normal vehicle data traffic is flowing on the serial bus, the D/A converter 11A is adjusted to a value where data transitions are established at the output 13 of the receiver 10. Having successfully accomplished this initial phase, the D/A converter 11A is then adjusted to a maximum value where transitions are lost. This...