Impact of Faults in Combinational Logic of Commercial Microcontrollers

This work shows that faults affecting the combinational logic embedded in a microcontroller can propagate to register elements and may have an important impact over applications, even in the most favourable case of short transient faults. Using VHDL-based fault injection techniques, we have experienced that the percentage of propagated faults, and thus their influence in the microcontroller upper layers, increases as clock frequencies rise. Experiments confirm that single faults can corrupt a number of registers at a time, this number being greater as the duration of the fault increases. From the application viewpoint, results show that, in some cases, faults can lead applications to fail in more than 80% of the cases, which suggests the need of improving the error detection and recovery mechanisms of existing commercial microcontrollers.