Serial data bus for serial communication interface (sci), serial

Abstract

The aim of the Chrysler Collision Detector (CCD) Bus System is to allow multiple microprocessors to easily communicate with each other over a common pair of wires (called a bus) using a scheme similar to a telephone party line. All microprocessors connected to the bus are able to receive all messages transmitted on the bus. Any microprocessor with a message to transmit on the bus waits until any current user is finished before attempting to use it. Whenever the bus is available, its use is allocated on a first-come, first serve basis (i.e., whichever microprocessor first begins transmitting its message on the bus after any previous message finishes gets the use of the bus). If, however, multiple microprocessors attempt to begin transmitting their messages on the bus at exactly the same time, then the message with the highest priority wins the use of the bus. All messages have unique message priority values and each message is transmitted by only one microprocessor. The subject invention provides the ability to communicate with a SCI port, a SPI port or a buffered SPI port. This allows communication with any device configured with any one of these ports, all on the same bus.