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undefined instruction exception

Question asked by Saravanan S on Jul 2, 2018
Latest reply on Jul 5, 2018 by jamesbone

We are using ARM Toolset , Toolchain MDK-ARM Professional Version 5.21a and Device is LPC2388.

We are trying to create a "undefined instruction exception" on a "BL" instruction in the thumb mode. When we tried to alter the H fllag in the first part of the instruction, we were unable to single step through the instruction as the instruction decoding was not successful. But when we moved the H flag altering to the second part of the instruction, the single stepping went through the instruction and proceeded to the next.

I wonder how on both the occasions the undefined instruction exception was created. This might cause a controller reliability issue in a mission critical system.

Can someone explain why the undefined instruction exception was not entered in our case and suggest a way of creating undef-exception on a BL instruction.

Thanks in advance.