Lpc2000

John,

I don't think this approach would solve the basic problem, which as 
I understand it is something like:

- system is using modem, which is on a call: hence DCD is asserted 
(low)

- software fails on the LPC2xxx (e.g. enters an infinite loop)

- external supervisor detects the problem and asserts RESET to reset 
the LPC2xxx

- as DCD (P0.14) is still low when reset happens, system enters boot 
loader mode

- system is now unrecoverable without manual intervention (as the 
original post said, a simple power cycle can do the actual recovery)

I guess you could use a hardware approach similar to the one you 
suggest to ensure P0.14 is high when RESET is asserted, as well as 
when power is 1st applied (on the basis that any re-flash will 
probably require manual intervention and override in any case). A 
simpler hardware fix as I previously suggested is just to avoid 
using the pin as DCD.

Unless of course I'm misunderstanding both the original post and 
your suggested fix....

Brendan


--- In lpc2000@yahoogroups.com, "John Heenan" <l10@...> wrote:
>
> What about a simple brute force hardware approach that 
> 1. Forces P0.14 high as soon as power is available.
> 2. Turns off the brute force during initialisation.
> 
> It is not pretty and depending on implementation may cost more 
power 
> than you might like.
> 
> John Heenan
> 
> 
> 
> --- In lpc2000@yahoogroups.com, "misstero" <suriyant@> wrote:
> >
> > Dear All,
> > 
> > I have design which is connected modem signals to UART1 (Full 
UART) 
> of
> > LPC2xxxx but I found serious problem with DCD signal.
> > 
> > DCD signal of UART1 is alternate function on P0.14 which is 
LPC2xxx
> > bootloader determine during reset to go into Bootloader mode if 
it 
> low.
> > 
> > Our problem occur when modem connected that DCD is active 
(Active 
> Low
> > same as bootloader mode request) and LPC2xxx is reseted which may
> > cause by unstable power or external reset via RESET pin by
> > supervisory. This made LPC2xxx  go into bootloader mode forever 
> cannot
> > return back to our application code even modem's DCD inactive 
later.
> > Only power cycle both LPC2xxx and modem to restart it to 
application
> > code. This case unaccetable when devices are installed in unman 
> location.
> > 
> > I have an idea to solve this problem but it need help from 
Philips 
> by
> > add time-out in Bootloader mode if it does not have any activity 
for
> > short period of time (etc. 3s) it should be retry to execute
> > application code repeatly so I'd like to ask Philips is it 
possible?
> > 
> > Anyone have other ideas to solve this problem? Please share with 
> me. I
> > prefer to solve by software first if it possible.
> > 
> > Thanks,
> > Suriyan.
> >
>