SAE 930006 Generic FMEA for Stand-Alone CAN Devices

930006Generic FMEA for Stand-Alone CAN DevicesCraig Szydlowski and Mukund PatelIntel Corp.ABSTRACTFa

930006 Generic FMEA for Stand-Alone CAN Devices Craig Szydlowski and Mukund Patel Intel Corp. 39 ABSTRACT The host-CPU programs its dedicated CAN chip to Failure Mode and Effect Analysis (FMEA) is auseful tool transmit/receive messages from the CAN bus; the CAN chip to aid in the detection and prevention of product defects. responds with interrupts after relevant bus communications FMEA's are used throughout the automotive industry to occur. The CAN chip relieves the host- CPU of the burden of facilitate the delivery of failure-averse modules to customers. monitoring all bus transmissions. The CAN chip interfaces to This paper applies FMEA techniques to generic stand-alone the CAN bus using abus driver. This bus driver is capable of Controller Area Network (CAN) chips. The CAN protocol, driving the bus while simultaneously sensing the bus value developed by ROBERT BOSCH GmbH, offers a through an independent receive pin. This functionality is comprehensive solution to managing communication between required since CAN is a"Carrier Sense, Multiple Access, with multiple CPUs. Collision Resolution" or CSMA/CR protocol(1). The CAN bus driver interfaces to atwo-wire CAN bus with signals typically Device-level FMEA's investigate the system-level impact called CAN-H and CAN-L. of electrical abnormalities on apin-by-pin basis. Conditions such as pins shorted to power or to other pins are evaluated for their effect on the system. Severity levels are also estimated. An FMEA for generic stand-alone CAN devices must consider failure modes for various pin types: power, clock, clockout, interrupt, mode selection, CAN bus, I/O ports, and address/data bus. In addition, this paper discusses how CAN devices detect and respond to bus errors and explores how the system may utilize this information in an FMEA analysis. COMPONENTS OF ACAN BUS NODE ACAN bus node has four components: host-CPU, CAN chip, CAN bus driver and the CAN bus. In this paper, these CAN node components are physically distinct, although it is clearly feasible to integrate two or more of these components onto asingle chip. Figure 1illustrates the CAN bus node. The host-CPU is amicrocontroller that performs an application function such as engine control or anti-lock braking. This host-CPU communicates with other modules to share sensor data and pertinent parameters and to implement diagnostic capabilities. Figure 1: CAN Bus Node