In-field Functional Test of CAN Bus Controllers

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. 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 relatively 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 test programs to be executed by the CPU connected to the device under test and by another unit connected to the same CAN bus. A fault grading with respect to structural permanent faults of a functional test based on the execution of a software test library for the CAN bus is presented for the first time. Results show how the approach can cover more than 90% of stuck-at faults on an open-source implementation of the standard, which is significantly more than what a usual functional test based on some sample application can achieve.