CDP68HC68S1

CDP68HC68S1 April 1994 Serial Multiplexed Bus Interface Description The CDP68HC6SS1 Serial Bus Interface Chip (SBlC) provides a means of interfacing in a Small Area Network configuration, various microcomputers (MCU’s) containing serial ports. Such MCU’s include the family of 68HC05 microcontrollers. The SBlC provides a connection from an MCU’s Serial Communication Interface (asynchronous UART type interface) or Serial Peripheral Interface (synchronous) to a medium speed asynchronous two wire differential signal bus designed to minimize electromagnetic interference. This two wire bus forms the network bus to which all MCU’s are connected (through SBI chips). See Figure 1. Each MCU operates independently and may be added or deleted from the bus with little or no impact on bus operation. Such a bus is ideal for inter-microcomputer communication in hazardous electrical environments such as automobiles, aircraft or industrial control systems. In addition to acting as bus arbitor and interface for microcomputer SCI port to differential bus communication, the CDP68HC68S1 contains all the circuitry required to convert and synchronize Non-Return-to-Zero (NRZ) 8-bit data received on the differential bus and clock the data into a microcomputer’s SPl port. Likewise, data to be sent by a microcomputer’s SPI port is converted to asynchronous format by appending start and stop bits before transmitting to other microcomputers. Refer to the data sheet for the CDP68HCO5C4 for additional infor...