undefined instruction exception

saravanans — Mon, 02 Jul 2018 10:40:20 GMT

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.

Re: undefined instruction exception

jamesbone — Thu, 05 Jul 2018 14:13:36 GMT

Hello Saravannan,

Please check the following : ARM Information Center

topic Re: undefined instruction exception in LPC Microcontrollers

undefined instruction exception

Re: undefined instruction exception