A simplified serial communication network within a vehicle

The authors propose a simplified serial communication network that is designed to perform real-time control in a distributed function system within a vehicle. The network has a ring type structure and the data transfer rate is 1 Mbit/sec. The network interface circuit is realized in a small gate size and is built in a communication interface circuit of microprocessors or intelligent sensors of smart power ICs. The communication network is controlled by a communication controller whose gate size is about 300 gates. The network system is applied to a distributed function engine control system with six CPUs (central processing unit) connected with sensors and power devices for engine idle speed control of lean burn processes. The engine control system is shown to function successfully. The deviation of engine speed was less than 10 r.p.m. when engine idle speed was 550 r.p.m. and the airfuel ratio was 19