Robustness of Low-Cost Microcontroller-Based Data-Acquisition Systems in Engineering Education Laboratories: A Fault-Injection Benchmark Linking Sampling-Jitter Tolerance to Experimental Repeatability

Low-cost microcontroller data-acquisition (DAQ) boards are now common in undergraduate engineering laboratories, yet their tolerance to sampling jitter and its consequences for experimental repeatability remain poorly characterised. The benchmark is formalised as a before-after-control-impact (BACIP) design with a declared variance structure (between-cluster SD = 6.0, residual SD = 4.5, intraclass correlation = 0.64), and its operating characteristics are evaluated across 2000 replications per design cell for cluster counts of 8, 16, 24 and 32 and effect sizes of 3, 5 and 8 percentage points. Power analysis indicates that 54 clusters are required to detect a 5-percentage-point effect at 80% power under this variance structure. The contribution is a reproducible protocol that converts jitter tolerance into a design-level statement about repeatability, allowing laboratory instructors and instrument designers to specify admissible jitter bounds rather than relying on nominal resolution alone. The analysis is methodological and does not report observational data; all quantities are derived from the declared variance structure and the BACIP estimator.