Migrate from HCS12 to HCX12

Eric_t — Fri, 14 Mar 2014 11:07:30 GMT

Hi,

I have two projects with mc9s12dg256 (256KB flash, 12KB RAM)

The first one uses 220KB flash and the whole 12KB of RAM.

The second uses 32 KB of flash and 2KB of RAM.

Now I have to merge the two projects to mc9sxdt512 controller.

I have successfully moved the first project to mc9sxdt512 (many thanks to Edward Karpicz for his excellent answer at this post:https://community.freescale.com/message/334626#334626)

The problem is that the first project uses the whole unpaged RAM, so the second project has to use the paged RAM.

Unfortunately moving pointers and variables to paged RAM is not so easy. The project implements Can Open and it was developed by another person.

I am wondering if there is any kind of solution to have more linear unpaged RAM (Actually I need 14KB)

Thank you

Nikos

Re: Migrate from HCS12 to HCX12

lama — Wed, 09 Apr 2014 13:15:14 GMT

Hi,

looking at the memory map (see attachment) there are two ways how to create linear RAM. However, nothing is direct access.

1) use global address to access RAM (linear space from 0F_B000-0F_FFFF)

2) use XGATE as a support device for RAM addrssing

3) use special routine which is converting your, let's say, imaginary linear space to paged space.

The first approach looks to be the easiest - far pointer is the solution. In the attached XDP512 - RAM addressing - CW45 you will see how to do that.

Best regards,

Ladislav