Lpc2000

Use a transceiver chip with an enable pin.  The enable
is controlled by the micro so on reset the transceiver
is disabled and thus the micro will not go into
bootloader mode.

--- brendanmurphy37 <brendanmurphy37@...> wrote:

> 
> 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.
> > >
> >
> 
> 
> 
> 
> 


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