In-Field Functional Test of CAN Bus Controller

The Controller Area Network (CAN) bus is a serial bus protocol widely used in the automotive domain to allow communication between different Electronic Control Units in the car. This communication peripheral has been developed with the goal of having robust systems with respect to external noise, hence the typical application in automotive-oriented products. Being often part of safety-critical systems, the hardware implementing the CAN network must be constantly tested along the system lifetime, even during the operational phase. CAN controllers are complex modules in charge of managing the sending and the receiving of packages through the CAN bus and defects affecting them can easily compromise the whole CAN network. In this work, the CAN controller is tested by means of test programs installed on the device under test and on another device connected to the same CAN bus. A fault grading with respect to structural faults of a functional test based on the execution of a software test library for the CAN bus is presented for the first time. The followed steps to perform such tests involve, starting from an open hardware implementation, the integration of the CAN Controller module in an OpenRisc SoC, followed by the development of all of the required drivers. Lastly, once the created environment showed to work flawlessly, test programs were written and simulated in order to conduct the aforementioned tests. To validate our work and show how it compares to other - more realistic, as they reflect typical communication scenarios among ECUs - programs, a few other tests have been created and compared to the main one. Results show how the approach can cover nearly 90% of all of the stuck-at faults.