9S08AW60 - Execution from protected flash

[Skippy]

Data Sheet:  MC9S08AW60 Data Sheet, Rev 2 implies in the last paragraph of  "4.4.6 FLASH Block Protection"  that a bootloader programmed into a protected section of FLASH is able to erase and program un-protected sections of FLASH.  To me this means that my FLASH programming functions can be executing out of flash and do not need to be relocated to RAM.  Any comments or experience in this area?

Thanks!

[peg]

Hi,

Unclearly written passages in datasheets WILL NOT change the characteristics or limitations of the flash memory used in these devices.

The limitation of not being able to execute from and write to flash in the same array at the same time remains.

[Skippy]

Hi Peg,

I know that "wishing doesn't make it so" and I have been reading and attempting to interpet Motorola/Freescale data sheets since the xc6800. Sometimes with pretty good results. Although in this case I think I got the answer from a local Arrow FAE.  He says "he thinks that if the sector, block, page or section  (choose your definition of a 512 byte FLASH block) is not protected and if the operational code is in a protected sector that the erase/burn functions should be able to live in that protected FLASH section".  IOW, don't try to program the block that is running code.

[peg]

Arrow FAE's "thinking" don't make it so either.

[Skippy]

Yes, well, we will wait, of course, to see what the lad has to say after he reads up on the official documents.

[Skippy · Accepted solution]

Word from above is that the FLASH array in 9s08AW60 is a single element. So, can't read and write indivisibly. Load the write functions to RAM and move forward.

[daveraymond]

I believe your data sheet will say something like:

This bootloader program can call a routine outside of Flash that can be used to sector erase the rest of the Flash memory and reprogram it.

The key words are outside of Flash. That is our experience.

Dave Raymond