Illegal opcode

luter · ‎2006-02-28

Posted on March 01, 2006 at 08:50

Illegal opcode

luter · ‎2006-02-28

Posted on March 01, 2006 at 03:55

I still prefer to use illegal opcode execution to reset micro.

wolfgang2399 · ‎2006-02-28

Posted on March 01, 2006 at 07:26

Hi Luter,

if there is no power down, the RAM contents will be unchanged. But as you said they don't mention it in their documents.

And as well _luca is right! The startup-routines of Cosmic and MetroWerks will initialize the global RAM-area. You must save the specific cell before the startup-routine. That's a little bit awkward!

As for me, I can't use the Illegal Opcode Reset because I need the reset pin for ''wired AND'' to reset my hardware around. While the ST7MC pulls down the Reset pin on illegal opcode detection, the ST2Lite doesn't have this feature. Older micros even don't have illegal opcode detection.

Finally thank you for having posted this stimulating issue.

Regards

WoRo

pete3 · ‎2006-02-28

Posted on March 01, 2006 at 08:50

If your micro has a paged area of RAM (e.g. a CANbus controller, hint hint) the COSMIC routine at least is generalised and will not detect the pages. You can write to a paged register not on page 0 and this will be preserved even after the startup routine is executed. This works on a WDG reset but not on a power-down reset when the RAM will power down.