Lpc2000

Hello Guille,

In case of a watchdog triggered reset, P0.14 pin is ignored by the
bootloader and the valid user application is executed. If valid user
application is not found then only isp is entered. In LPC2138 the WDT
flag is not cleared by pin reset. POR reset clears the WDT flag. What
you are observing is expected behavior. I am assuming that WD reset
happened since you have mention it.

Regards
Philips Apps

--- In lpc2000@yahoogroups.com, "Guillermo Prandi"
<yahoo.messenger@...> wrote:
>
> Hi, I wonder if anyone has seen this before.
> 
> While developing the firmware for my LPC2138-featured board, I noticed 
> that the bootloader is not always invoked after a reset with P0.14 low. 
> Even when the bootloader is not invoked, the device still responds to 
> reset.
> 
> I tested with the Philips bootloader utility, which, measured at the 
> reset and P0.14 pins, gives me:
> 
> 1) At T+0, P0.14 goes down from 3.3V to 0V sharply.
> 2) At T+0, Reset starts going down from 3.3V to 0V in an RC-type curve 
> of 750µS.
> 3) At T+750µS both Reset and P0.14 are now 0V.
> 4) At T+500 mS reset starts going up, having been effectively low for 
> 499mS. The rising curve is also RC-type and takes about 2 mS to reach 
> 85%.
> 5) At T+840 mS, P0.14 goes up sharply. This is 338 mS *after* reset 
> went high.
> 
> By the spec, these figures should be large enough to trigger the 
> bootloader, and it does, except when I've been playing around with my 
> firmware for a while (several cycles of compile+flash programming, 
> tests, an occasional crash, watchdog triggered, etc.). When the 
> bootloader stops responding, the only way to regain the bootloader is 
> by removing power.
> Any ideas?
> 
> Guille
>