Lpc2000

Michael,

I did mean P0.31 not P1.31.  P0.31 is an output only pin but according
to the information that I got, it gets sampled at reset and can
generate weird things if it is low @ reset.

Bob

--- In lpc2000@yahoogroups.com, "michael_rubinstein_sar"
<michael_rubinstein_sar@y...> wrote:
> Hi Bob, thanks for the help.
> 
> I'll bet you meant 1.31 (\TRST).  This signal is not connected on 
> our board.  However, it is driven high by the JTAG gizmo (J-Link).
> 
> The other problems are really odd.  After an external reset, some of 
> the I/O pins just don't work.  I tried disconnecting 0.18 from other 
> circuitry, programming it as a gpio output and toggling it a few 
> times.  It works as expected after a power-up but just stays low 
> after an external reset.
> 
> My code doesn't know the difference between a power-up reset and an 
> external reset.  I wonder if the ISP code behaves differently before 
> it transfers control to my code.
> 
> Michael
>  
> 
> --- In lpc2000@yahoogroups.com, "lpc2100_fan" <lpc2100_fan@y...> 
> wrote:
> > Hello Michael,
> > 
> > one possible reason although this might not seem related.  If you 
> have
> > an external signal on pin 0.31 that would drive this pin low during
> > reset (no matter which reset), the LPC2138 will no longer enable 
> the
> > JTAG.  Please make sure that P0.31 not driven externally (has a 
> weak
> > pull-up) when any reset occurs. 
> > 
> > hth, Bob
> > 
> > 
> > 
> > --- In lpc2000@yahoogroups.com, "michael_rubinstein_sar"
> > <michael_rubinstein_sar@y...> wrote:
> > > I'm debugging a new 2138 based design.
> > > 
> > > If the board is powered up, eveything works as expected.  
> However, if 
> > > an external reset (\RESET) is then applied, several funny things 
> happen:
> > > 
> > > o  JTAG stops working.
> > > o  P0.18 which is configured as a timer capture input, sinks 
> current.
> > > o  P0.4 which is used as SPI SCK, in master mode, stops going 
> high.
> > > 
> > > I verified the values in PINSEL, IODIR and IOSET.  They are 
> correct and 
> > > the same in both cases.
> > > 
> > > Any help appreciated.
> > > 
> > > Thanks,
> > > Michael Rubinstein