Lanzieri, LeandroLeandroLanzieriFey, GörschwinGörschwinFeySchlarb, HolgerHolgerSchlarbSchmidt, Thomas C.Thomas C.Schmidt2026-07-302026-07-302026-0531st IEEE European Test Symposium, ETS 2026https://hdl.handle.net/11420/64155Microcontrollers in critical systems require monitoring of hardware ageing to avoid unexpected malfunctioning. We previously introduced a deployable timing-based method with self-tests for ageing monitoring in commercial microcontrollers that relies solely on user-level information. While effective, manually constructing computing payloads for system-level tests can limit scaling and coverage of hardware-specific critical paths or subsystems. In this paper, we complement our technique with an automated generation of the self-test firmware. We explore several approaches for generation using hardware in the loop (HiL) evaluation on commercial microcontrollers, including a random generation and evolutionary strategies. In the evolutionary approach, we investigate two mutation mechanisms: random selection, and contextual bandits. Our evaluations on real hardware and a surrogate model show the impact of evaluation budget and algorithm selection on the effectiveness of automatic self-test generation. Results reveal that random generation is well suited to reduced HiL explorations, while evolutionary strategies benefit from extended evaluations. Our Hil-based technique is able to produce firmwares with up to double the degradation sensitivity as the functional tests provided by the vendor.enEvolutionary strategySystem-level testingTest generationComputer Science, Information and General Works::004: Computer SciencesConference Paper10.1109/ETS69887.2026.11591921