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Newbie question on memory access and exceptions on HCS12X

Question asked by bob holder on May 14, 2011
Latest reply on May 15, 2011 by bob holder

Hi Folks,

  I am new to the HCS12x and have a question regarding memory access and exceptions. If this is FAQ my apology upfront.

 

Setup

CodeWarrior 5.1, target is mc9s12xdt512 and FCS.

 

My question:

What happens to a memory write to a variable in a C program that is const and placed in onboard flash (READ_ONLY) segment C000? Does the program continue running or will it raise an exception and halt?

 

When I run the program on the target hardware it seems to run ok. But when I run it under the Full Chip Simulator (FCS) the simulator halts the program at the write call with error message "Protected at XXXX".

 

On x86 Windows/Linux a bad write like this would cause global protection fault/segmentation fault and core dump.

Will the physical mc9s12xdt512 allow/ignore this bad write but the simulator will stop and alert me?

 

thank you

bob

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