Acquisition of distributed CAN traffic for centralized analysis at functional and electrical levels

Abstract: This thesis covers specification and development of a distributed measurement system intended for CAN bus. It was completed at Scania CV, Södertälje in collaboration with Lund University. The goal of the thesis is to specifiy and develop a distributed measurement system that helps Scania with acquisition of functional and electrical data. Several topics are adressed such as filtering, at what speed the system shall run at and much more. By a thorough pre-study that began with reading of specifications and continuing into measurements of the bus, a number of requirements was produced to reach a specification to be able to begin development. Development was done by producing a custom hardware controller that handles the incoming data and performs a conversion to logical data. This controller is in turn connected to a system bus on the evaluation board that makes it possible to write directly into the CPU's RAM. Due to this, valuable CPU time that would be spent fetching data is saved and the CPU can be used for signal processing and handling the upstream connection to a server instead. In addition to this, an input stage that handles interaction with the CAN bus was produced. It is essential that the bus is not affected by the measurement system. Furthermore this stage filters the signal to minimize aliasing from the ADCs. The developed system aims to increase knowledge of the electrical behaviour of the bus as well as a new method to acquire logical information from the bus. With more development, a custom PCB could be manufactured that could be placed on-board for increased vehicle diagnostics. Finally, tips and ideas for further development are suggested.