8-bit MicrocontrollersのトピックRe: 9S08AW60 - Execution from protected flash

9S08AW60 - Execution from protected flash

Skippy — Thu, 28 May 2009 04:58:53 GMT

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!

Re: 9S08AW60 - Execution from protected flash

daveraymond — Thu, 28 May 2009 05:31:00 GMT

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

Re: 9S08AW60 - Execution from protected flash

peg — Thu, 28 May 2009 06:14:48 GMT

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.

Re: 9S08AW60 - Execution from protected flash

Skippy — Thu, 28 May 2009 06:29:52 GMT

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.

Re: 9S08AW60 - Execution from protected flash

peg — Thu, 28 May 2009 18:03:46 GMT

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

Re: 9S08AW60 - Execution from protected flash

Skippy — Thu, 28 May 2009 23:25:25 GMT

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

Re: 9S08AW60 - Execution from protected flash

Skippy — Tue, 02 Jun 2009 07:21:44 GMT

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.