Hai all, I am working on saftey critical application,so my requirement is to validate the code memory at run time.. Is there any method to validate the code during runtime...calculating check sum at runtime and verifying is possible and effective ??...
There is the Power ON testing that validates the firmware, hardware, and other requirements of the safety criteria. There is also continuous testing of the system, and commanded testing of the system.
A power on Built-In Test (BIT) (or Basic Internal Test in some circles) is performed to ensure that the system is ready and safe to operate.
A continuous BIT (CBIT) is performed as part of the regular duties of the software. This can monitor supply voltages, validate I/O states, do checksums, etc.
In addition, some systems can be designed to do a more thorough commanded BIT that performs either a specific type of testing or a whole battery of tests.
By designing in these types of testing, you can increase your reliability (or at least track it), and/or avoid a larger failure through early detection.
The "what to do if it fails" is highly application dependent. But I'm sure that this was covered in your system design plan anyway. (a tinge of sarcasm there)
Since the boot-time BIT takes time, you'll have to balance that with the "power-on to first action" time allowed in your system. While the CBIT can be done more leisurely, and split up between tasks or during "idle" states.
--Cpt. Vince Foster 2nd Cannon Place Fort Marcy Park, VA