Lpc2000

Let's say MEMMAP's initially configured as 1 (flash mode), and I 
plan todo a complete firmware update using IAPs. If I remapped the 
interrupt vectors to RAM (MEMMAP = 2) before overwriting segment 0, 
will the original vectors remain preserved in RAM?

--- In lpc2000@yahoogroups.com, "Leighton Rowe" <leightonsrowe@y...> 
wrote:
> Let's say MEMMAP's initially configured as 1 (flash mode), and I 
> plan todo a complete firmware update using IAPs. If I remapped the 
> interrupt vectors to RAM (MEMMAP = 2) before overwriting segment 0, 
> will the original vectors remain preserved in RAM?

Before changing MEMMAP from 1 to 2, you should write whatever you 
want as interrupt vectors to RAM (0x4000_0000 - 0x4000_003F).  
Changing MEMMAP doesn't by itself copy anything from flash to RAM.

Relocating the interrupt vectors to RAM is only necessary if you need 
to handle interrupts during the flash writing.  In that case, you 
should also copy the interrupt handlers themselves to RAM.  It might 
be easier to just disable all interrupts and use polled I/O.  When 
updating the whole flash, you of course have to copy the firmware 
updating code to RAM as well.

Karl Olsen

> Before changing MEMMAP from 1 to 2, you should write whatever you 
> want as interrupt vectors to RAM (0x4000_0000 - 0x4000_003F).  
> Changing MEMMAP doesn't by itself copy anything from flash to RAM.

Makes much more sense now. I'm able to get the RAM Mode working. 
Thanks.

> Relocating the interrupt vectors to RAM is only necessary if you 
need 
> to handle interrupts during the flash writing.  In that case, you 
> should also copy the interrupt handlers themselves to RAM.  It 
might 
> be easier to just disable all interrupts and use polled I/O.  When 
> updating the whole flash, you of course have to copy the firmware 
> updating code to RAM as well.

I'd rather go with updating segments (not containing the original 
program code) with the new program (int handlers included). That way 
flash functions won't have to be copied and executed in RAM. I hope 
this suggestion isn't too hard to pull off.

Leighton