Lpc2000

Thanks, Richard. Unfortunately my device uses all the available GPIO 
pins, so I am unable to use JTAG.

Guille

--- In lpc2000@yahoogroups.com, Richard Duits <yahoo@...> wrote:
>
> Guillermo Prandi wrote:
> > Oh, I think I see the point, now. From what you say I get the
> > following:
> >
> > 1) I have no choice but to go through the embedded bootloader for 
the
> > initial programming.
> >
> You can use JTAG to upload your own code to RAM and execute this, 
so if 
> you really do not want to use the philips bootloader you can use 
JTAG to 
> do whatever you want. Philips uses this same method to program the 
> bootloader and test the device. You also have an extra flash sector 
you 
> can use if you are short on flash and like to do everything 
yourself.
> 
> > 2) Using the embedded bootloader should work if I am careful 
enough
> > to provide the correct crystal frequency. However, as the writing
> > procedure seems to be poorly implemented, a write-read-compare 
cycle
> > should be considered.
> >
> Maybe philips chose to use a delay loop because the hardware bits 
were 
> not reliable enough. Has anyone tested these hardware bits with 
> diffirent core frequencies to see if they work ok? I would be happy 
to 
> try some code if anyone has programmed their own flash programming 
routines.
> 
> > 3) I might get a non-functional unit if my program misbehaves and
> > accidentally runs code that erases the provided bootloader. This
> > is "unavoidable" since the processor lacks some kind of hardware
> > protection to prevent this to happen accidentally.
> >
> If the bootloader is erased, the hardware should be accessable with 
> JTAG, because there is no bootloader code to disable it.
> 
> > 4) I have the choice (however undocummented) to write my own
> > bootloader. If this bootloader lacks flash memory programming
> > capabilities I might be safer because my potentially misbehaving
> > application will not be able to jump in the middle of the flash
> > programming code and accidentally erase the bootloader or other 
parts
> > of the flash.
> >
> Until now I have never seen a LPC2xxx with a trashed bootloader, so 
I am 
> happy with what I have now.
> 
> 
> > Correct me if I'm getting you wrong.
> >
> > Guille
> >
> 
> Richard.
>