Lpc2000

--- In lpc2000@yahoogroups.com, "jayasooriah" <jayasooriah@y...> wrote:
>
> Hello,
> 
> An application code being debugged on LPC device that crashes can
> execute code in boot sector and cause the device to self-destruct.
> 
> This is because the code provided by Philips in boot sector is not
> protected from inadvertent execution.

I suppose they could generate an interrupt on execution of any part of
the bootloader other than the first few bytes which would contain code
to turn off the interrupt.  But what if you had all interrupts
disabled when you entered the erroneous section?  

 
> Furthermore the algorithms for programming LPC flash do not require
> any feed sequences (eg 0xaa followed by 0x55) as is the industry
> practice.  

I never bother with this sort of code because it provides very little
protection.  Errant code can always jump to the area after the code
that checks the "feed" sequences.  


> For these reasons, I want to replace Philips boot loader with my own.
> The aim is to not have any flash programming code at all in the boot
> sector, or for that matter, in any flash sector.
> 
> My bootloader allows you to load and run code by simply copying and
> pasting Intel-hex load files onto Minicom or HyperTerm window to the
> serial port.  This is another reason why I want to replace the loader
> provided by Philips.
> 
> Has anyone replaced Philips boot loader code for any LPC device?

So your new code would provide a RAM based bootload which can load a
program to program the flash?  That can be more secure, but make sure
you wipe the programming code after you use it so that you can't
accidentally execute it in RAM.  

Just my 2 cents worth.