unexpected jump

epassoni9 · ‎2009-10-25

Posted on October 26, 2009 at 05:31

unexpected jump

epassoni9 · ‎2011-05-17

Posted on May 17, 2011 at 15:05

What happens if the program counter goes to a location loaded with 0x00?

(for example,I know that if the location contains a ''nop'' op-code it goes to the next location.)

Since the 0x00 is not an op-code,what happens ? thanks! :)

Thanks

Spectre

p.s. I have already read the an on the emc interferences

brazov2 · ‎2011-05-17

Posted on May 17, 2011 at 15:05

Hi,

if the micro decodes and illegal opcode, you'll get an illegal opcode reset. Check the status register of the reset controller to see reset source.

Coluber

epassoni9 · ‎2011-05-17

Posted on May 17, 2011 at 15:05

Dear brazov2,

I didn't understand your answer.I know that I can check the reset source but I have mentioned the emc application note only because I have read on it the illegal op-codes list.

I agree with you that if the program counter pointer goes on a illegal op-code I'll get an mcu reset.But I'm interested about a block filled with 0x00.

regards

Spectre

[ This message was edited by: spectre on 23-10-2009 14:19 ]

brazov2 · ‎2011-05-17

Posted on May 17, 2011 at 15:05

Hi spectre,

can you better specify the problem you want to solve? If you want to remove illegal byte 00h from your code and you have a block of all zeros, perhaps you can simply fill it with TRAP opcode (83h) to keep a better control of unexpected jumps instead of getting an illegal opcode reset.

coluber

epassoni9 · ‎2011-05-17

Posted on May 17, 2011 at 15:05

Dear brazov2,

I have solved my issue.

(I was not sure that 0x00 is an illegal opcode.)

regards

Spectre :)