Lpc2000

Hi Guile,

Based on my own experience, and of those who have communicated such 
problems to me by email, there are two reasons as to why you may need to 
consider custom boot loader in your case where you are not concerned with CRP.

1/  The coding of the flash programming algorithm in the boot loader 
unreliable because: a) it depends on wait loops rather than polling the 
flash controller status register; and b) it requires clock frequency to be 
passed as a run-time argument.

2/  The boot loader includes code that writes to flash, and as the flash 
device is not protected by feed sequences (industry standard for flash 
memories) you can get accidental trashing of the boot loader when the 
application misbehaves.

I recommend that the boot loader be replaced with one that is simple and 
does not include flash programming code.  A simple loader is less likely to 
be plagued by bugs.  The absence of code to program flash makes it more 
robust with respect to application misbehavior in the field.

There is nothing we can do about the flash device not having industry 
standard protective feed sequences -- so the less code there is in memory 
that is capable of modifying on-chip flash, the safer your system is going 
to be in the field.

Field upgrades can be done by sending down your upgrade application that 
includes flash programming code which is discarded once the upgrade is 
complete.  The code to program the flash is minimal -- at last count my 
flash library itself (written in C) was 820 bytes.

Hope this helps.

Jaya

--- In lpc2000@yahoogroups.com, "Guillermo Prandi" <yahoo.messenger@...> wrote:
 >
 > Thanks, Jayasooriah.
 >
 > This however leaves me with more questions than before. I am not
 > particularly interested in code read protection. However, my company
 > designed a board using LPC2138/LPC2148 and I would like to know if I
 > am likely to encounter problems when programming those boards, what
 > kind of problem will they be and if can or can't I avoid them. We use
 > plain UART0 interface for the one-time programming (occasionally, a
 > firmware upgrade might kick in, also using the standard bootloader).
 > We will be using the Philips utility for the task. If you have some
 > info about that, please let me know.
 >
 > Guille

Send instant messages to your online friends http://au.messenger.yahoo.com