Design and implementation of a military compliant interface between communication buses applied to CAN bus and ethernet

Abstract

This paper presents the entire redesign of an existing electronic board (named the octoCAN board), which has been carried out within the CMI Defence company. The device is an extended version of a CAN (Controller Area Network) bus bridge. The function of such a bridge is to repeat the incoming CAN messages to other sections of the comprehensive CAN network. The current octoCAN board includes eight microcontrollers, each one of them handling the repetition of the incoming message on one of the eight independent CAN branches. The heart of the master thesis is considered to be broken down into three main axes. The first objective consists in reducing to two the number of MCUs present on the board. Two different configurations based on the SPI bus protocol have been implemented on the new prototype PCB. A code developed with Mbed allows to fulfill the CAN messages repetition function. A second objective is to characterise the electromagnetic compatibility of the new PCB. Both the theoretical design and practical measurements in a semi-anechoic chamber have been performed. Hardware filters have been implemented in order to mitigate the electromagnetic interferences. The noise level measurements have been carried out for the conducted and radiated emissions (CE102 and RE102 tests of the MIL-STD-461-G standard). The obtained curves have been analysed. Lastly, the third objective involves the introduction of an Ethernet port on the PCB. This has been conducted for maintenance and debugging purposes.