Integrated J1850 Protocol Provides for a Low-Cost Networking Solution

The J1850 specification was officially adopted by SAE as the standard protocol for Class B in-vehicle networks on February 1 1994 J1850 has been a recommended practice for seven years and has gained wide acceptance throughout North America Today J1850 is implemented in many production vehicles for data-sharing and diagnostic purposes The widespread integration of J1850 in-vehicle networks is contingent upon low-cost implementation into apphcations such as ABS engine, transmission and instrumentation In order to address this need, Intel Automotive has developed a very low-cost J1850 protocol handler designed specifically to be integrated onto high-performance MCS®96 microcontrollers.

This paper introduces Intel's J1850 protocol handler which supports both GM and Chrysler versions of J1850 Integrating the J1850 protocol onto microcontrollers allows for faster access and therefore reduces service overhead The described J1850 protocol handler will handle network protocol functions including access arbitration in-frame responses, error detection and delay compensation A digital noise filter automatically rejects unwanted noise pulses Three dedicated interrupts and byte-level message buffering provide for efficient interrupt handling This implementation is consistent with the industry's goal to drive J1850 implementation below $2 00 per node.