Consumption meter with one processor handling legal and non-legal code

摘要

A consumption meter, e.g. for charging purposes, arranged to measure a consumed quantity (Q) of a physical entity. The meter has a measurement circuit (MC), a memory (M), a memory management unit (MMU) for handling access to areas of the memory (M) according to respective access rights assigned to different tasks, and a processor (P). The processor (P) can access the memory (M) through the memory management unit (MMU), and execute executable code (T1, OS) stored in the memory (M). The processor (P) can execute a vital meter calculation task (T1) with a first access right (PL3) assigned thereto which results in storing a calculated consumed quantity (Q) in a first memory area. Finally, the processor (P) can execute an operating system (OS) which can temporally limit execution of executable code other than the calculation task code (T1). This architecture of a consumption meter allows one single processor (P) to be used for handling legal and non-legal tasks, and the memory management unit (MMU) serves to ensure that no data used by a legal task can be destroyed by a non-legal task. Further, since the operating system (OS) can handle possible temporal conflicts between non-legal and legal tasks, it will be possible to change executable program code for non-legal tasks without the requirement of a renewed authority approval of the meter.