Memory Mapping in MC9S12NE64

[morag]

Hi

I am struggling to get my address mapping on the NE64 correct. I am working in Normal Expanded Wide Mode, I have enabled the Flash, ROMON = 1 and my external RAM is mapped into address 0x00018000 to 0x0001BFFF. My question is, am I able to use address 0x00008000 to 0x0000BFFF for code space (ROM)and if so how do I go about doing that?

Many thanks
Morag

[Goz]

The flash is divided into 4 areas of useable memory. You haven't mentioned if you are paging any of the memory, but for example you may have the following....

Non-paged onboard Flash memory at 0x4000 through to 0x7FFF and from 0xC000 through to 0xEFFF where 0xF000 through to 0xFFFF will be a secured area for vector tables, bootstrap etc.

The remaining two areas of onboard flash that are paged may reside at 0x3C8000 to 0x3CBFFFand 0x3D8000 to 0x3DBFFF.

If you use this kind of configuration then your external memory can start from 0x008000, you have to set this up in your .prm file. You ask if you can use 0x008000 as your ROM space.....are you implying that your external memory is ROM? or is it RAM?

if it is RAM then no your volatile memory would start at 0x008000 in this example and you will have to use the onboard flash as your non volatile storage at 0x4000 or at 0xC000.

I think you may have to include a little bit more detail on what your exapnded memory consists of.

Message Edited by Goz on 2006-10-2011:14 AM

[morag]

Hi Goz

Thanks for the response. I figured it out just after I posted the message. My external memory is RAM so i have relocated it to 0x08000 and everything seems to be running okay now.