problem of 9s12dp512 memory map?

jeffzxg — Sat, 17 Jan 2009 12:12:38 GMT

hi all

dp512 has the following on chip resource: 1K register; 4K eeprom; 14K ram; 512K flash; where two 16K unpaged flash is located at $4000 ~ $7fff and $c000 ~ $ffff. and the reset address space for register is $0000 ~ $03ff ; eeprom is $0000 ~ $0fff ; ram $0800 ~ $3fff. priority is register > ram > eeprom > flash.

so after reset the available space for register is 1K($0000~$3ff) ; ram 14K ($800 ~ $3fff) ; eeprom 1K ($400 ~ $7ff), but i want to fully use of 4K eeprom and 14K ram , so i have to remap the memory map of eeprom and ram space.

ram space extended to next 16K address space ($4000 ~ $7fff) , according to the priority of on chip resource, the unpaged flash block ( $4000 ~ $7fff ) is overlapped.

my question is: if the unpaged flash block ( $4000 ~ $7fff ) is overlapped, does that mean i can not place any application code to that area? if it is right, is there any method that can use the overlapped flash areas?

thanks!

Re: problem of 9s12dp512 memory map?

kef — Sat, 17 Jan 2009 16:21:56 GMT

If you overlap part of unpaged 4000-7fff flash by RAM or EEPROM, then this overlapped flash is not accessible as unpaged flash, but it can be accessed as paged flash on PPAGE 3E.

I would move not 14k RAM but 4k EEPROM to 4000-4FFF. It would cover less of valuable unpaged flash. Unpaged flash is effective place to store const strings and const data. Accessing data from paged flash is cumbersome on S12.

S12 / MagniV Microcontrollers中的主题 problem of 9s12dp512 memory map?

problem of 9s12dp512 memory map?

Re: problem of 9s12dp512 memory map?