This paper presents a non-intrusive framework for runtime verification of executable microcontroller code. A dedicated hardware unit is attached to a microcontroller, which executes the program under scrutiny, to track atomic propositions stated as assertions over program variables. The truth verdicts over the assertions are the inputs to a custom-designed
CPU unit that evaluates past-time LTL specifications in parallel to program execution. To achieve this, the instruction set of the
CPU is tailored to determining satisfaction of specifications.