Hi Guile, I should have said "power on reset".

I removed the problem (was not keen on solving it at that time) by avoiding 
use of GPIO pins that the boot loader has allocated for purposes of 
"external boot" feature (something that is not necessary and hence of 
dubious value in the context of embedded systems).

I believe there are some registers that the boot loader fiddles with which 
exhibit "stuck zero" behaviour -- when one writes a zero, these bits
stays 
zero until power on reset event.

In the 2292 that I am now working on for POE application, I found that if 
you do not re-map interrupt vectors to your own memory space, UND, PRE, and 
ABT type exceptions can also cause the system to lock up in similar 
ways.  Power on reset got me out each time this happened.

Jaya

>    Date: Tue, 07 Feb 2006 13:07:11 -0000
>    From: "Guillermo Prandi" <yahoo.messenger@...>
>Subject: Re: Bootloader not always invoked after reset with P0.14 low
>
>Hi, Jayasooriah. What do you mean by "hard reset"? If you mean
having
>the reset pin low, then I *am* performing a hard reset. The problem
>shows up when I attempt to access ISP via serial port (DTR goes to
>RESET, RTS goes to P0.14).
>
>Guille

Send instant messages to your online friends http://au.messenger.yahoo.com 

Ooof... seems like a stinky sticking problem. I'll better attack it 
only if it becomes a real PITA. For the moment, instructing the 
programming operator to do a power-on reset by hand is perfectly 
acceptable.

Thanks a lot.

Guille

--- In lpc2000@lpc2..., Jayasooriah <jayasooriah@...> wrote:
>
> Hi Guile, I should have said "power on reset".
> 
> I removed the problem (was not keen on solving it at that time) by 
avoiding 
> use of GPIO pins that the boot loader has
allocated for purposes of 
> "external boot" feature (something that is not necessary and
hence 
of 
> dubious value in the context of embedded systems).
> 
> I believe there are some registers that the boot loader fiddles 
with which 
> exhibit "stuck zero" behaviour -- when
one writes a zero, these 
bits stays 
> zero until power on reset event.
> 
> In the 2292 that I am now working on for POE application, I found 
that if 
> you do not re-map interrupt vectors to your own
memory space, UND, 
PRE, and 
> ABT type exceptions can also cause the system to
lock up in similar 
> ways.  Power on reset got me out each time this happened.
> 
> Jaya
> 
> >    Date: Tue, 07 Feb 2006 13:07:11 -0000
> >    From: "Guillermo Prandi" <yahoo.messenger@>
> >Subject: Re: Bootloader not always invoked after reset with P0.14 
low
> >
> >Hi, Jayasooriah. What do you mean by "hard reset"? If you
mean 
having
> >the reset pin low, then I *am* performing a
hard reset. The problem
> >shows up when I attempt to access ISP via serial port (DTR goes to
> >RESET, RTS goes to P0.14).
> >
> >Guille
> 
> Send instant messages to your online friends 
http://au.messenger.yahoo.com
>
	

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@lpc2..., "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 750S.
> 3) At T+750S 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
>
	

My code is clearing the RISR flags at boot time by doing:

#define RSIR (*((volatile unsigned char *) 0xE01FC180))

RSIR = 0x0f;

After that, the boards still ignores P0.14 after a watchdog reset. 
Since I cleared the watchdog reset flag, I expected the bootloader to 
invoke ISP. Is there anything else I could do from software in order 
to make the bootloader honor the P0.14 pin?

Guille

--- In lpc2000@lpc2..., "philips_apps" <philips_apps@...> 
wrote:
>
> 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@lpc2..., "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 750S.
> > 3) At T+750S 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
> >
>
	

Hi Guile,

If you look at the user manual for WTOF bit which the boot loader checks, 
it is quite clear that "external reset" will clear this bit.

Can you try without arming the watchdog to see if the problem goes away?

Jaya

--- In lpc2000@lpc2..., "Guillermo Prandi" <yahoo.messenger@...>
wrote:
 >
 > My code is clearing the RISR flags at boot time by doing:
 >
 > #define RSIR (*((volatile unsigned char *) 0xE01FC180))
 >
 > RSIR = 0x0f;
 >
 > After that, the boards still ignores P0.14 after a watchdog reset.
 > Since I cleared the watchdog reset flag, I expected the bootloader to
 > invoke ISP. Is there anything else I could do from software in order
 > to make the bootloader honor the P0.14 pin?
 >
 > Guille
 >
 > --- In lpc2000@lpc2..., "philips_apps" <philips_apps@>
 > wrote:
 > >
 > > 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

Send instant messages to your online friends http://au.messenger.yahoo.com 

Hi, Jayasooriah. Indeed the watchdog is the problem. At this stage of 
development I am only using the watchdog to provide a software reset 
function. Apparently this behavior is triggering only after using 
this function. And yes, you are right; the bit should be cleared by 
the external reset.

It looks like this behavior is 'by design' so there is no other 
workaround than switching off the unit.

Guille

--- In lpc2000@lpc2..., Jayasooriah <jayasooriah@...> wrote:
>
> Hi Guile,
> 
> If you look at the user manual for WTOF bit which the boot loader 
checks, 
> it is quite clear that "external reset"
will clear this bit.
> 
> Can you try without arming the watchdog to see if the problem goes 
away?
> 
> Jaya
> 
> --- In lpc2000@lpc2..., "Guillermo Prandi" 
<yahoo.messenger@> wrote:
>  >
>  > My code is clearing the RISR flags at boot time by doing:
>  >
>  > #define RSIR (*((volatile unsigned char *) 0xE01FC180))
>  >
>  > RSIR = 0x0f;
>  >
>  > After that, the boards still ignores P0.14 after a watchdog 
reset.
>  > Since I cleared the watchdog reset flag, I
expected the 
bootloader to
>  > invoke ISP. Is there anything else I could
do from software in 
order
>  > to make the bootloader honor the P0.14 pin?
>  >
>  > Guille
>  >
>  > --- In lpc2000@lpc2..., "philips_apps"
<philips_apps@>
>  > wrote:
>  > >
>  > > 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
> 
> Send instant messages to your online friends 
http://au.messenger.yahoo.com
>
	

The bootloader does not look at the RISR register. It looks at the
WDTOF flag in WDMOD register.
Even clearing of watchdog flag in user application may not help (if
timeout is too small) because the bootloader runs before application.

If you are using the watchdog only to trigger ISP then Reinvoke ISP
command might be a better choice. This was added to 213x,214x devices. 
Restore Timer1 to reset state if your application uses it.
Refer to Table 218 on page 235 of the user manual
http://www.semiconductors.philips.com/acrobat_download/usermanuals/UM10120_1.pdf

The LPC213x/214x user manual will be updated to reflect the WTOF clear
conditions.

Regards
Philips Apps

--- In lpc2000@lpc2..., "Guillermo Prandi"
<yahoo.messenger@...> wrote:
>
> My code is clearing the RISR flags at boot time by doing:
> 
> #define RSIR (*((volatile unsigned char *) 0xE01FC180))
> 
> RSIR = 0x0f;
> 
> After that, the boards still ignores P0.14 after a watchdog reset. 
> Since I cleared the watchdog reset flag, I expected the bootloader to 
> invoke ISP. Is there anything else I could do from software in order 
> to make the bootloader honor the P0.14 pin?
> 
> Guille
> 
> --- In lpc2000@lpc2..., "philips_apps" <philips_apps@> 
> wrote:
> >
> > 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@lpc2..., "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 750�S.
> > > 3) At T+750�S 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
> > >
> >
>
	

Oh, thanks Richard!

After your words, the following sequence in my startup code seems to 
do the trick:

WDMOD = 0; // I don't know if this is actually required
WDFEED = 0xaa;
WDFEED = 0x55;

Guille

--- In lpc2000@lpc2..., "philips_apps" <philips_apps@...> 
wrote:
>
> The bootloader does not look at the RISR register. It looks at the
> WDTOF flag in WDMOD register.
> Even clearing of watchdog flag in user application may not help (if
> timeout is too small) because the bootloader runs before 
application.
> 
> If you are using the watchdog only to trigger ISP then Reinvoke ISP
> command might be a better choice. This was added to 213x,214x 
devices. 
> Restore Timer1 to reset state if your application
uses it.
> Refer to Table 218 on page 235 of the user manual
> 
http://www.semiconductors.philips.com/acrobat_download/usermanuals/UM1
0120_1.pdf
> 
> The LPC213x/214x user manual will be updated to reflect the WTOF 
clear
> conditions.
> 
> Regards
> Philips Apps
> 
> --- In lpc2000@lpc2..., "Guillermo Prandi"
> <yahoo.messenger@> wrote:
> >
> > My code is clearing the RISR flags at boot time by doing:
> > 
> > #define RSIR (*((volatile unsigned char *) 0xE01FC180))
> > 
> > RSIR = 0x0f;
> > 
> > After that, the boards still ignores P0.14 after a watchdog 
reset. 
> > Since I cleared the watchdog reset flag, I
expected the 
bootloader to 
> > invoke ISP. Is there anything else I could do
from software in 
order 
> > to make the bootloader honor the P0.14 pin?
> > 
> > Guille
> > 
> > --- In lpc2000@lpc2..., "philips_apps" <philips_apps@>

> > wrote:
> > >
> > > 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@lpc2..., "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 750�S.
> > > > 3) At T+750�S 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
> > > >
> > >
> >
>
	

Hi Guile,

I am looking at what appears to be a different manifestation of the problem 
you encountered in that power cycling is required to recover form a lockup 
in order to transfer control to ISP by pulling P0.14 low.

Philips explains this happens can if "timeout value is too small". 
The 
user manual seems to say writing anything less than 0xff will result in 
minimum timeout of PCLK x 256 x 4.

The test code below then should create the lockup scenario, but it does not 
on my 2292.  I cannot see where I got it wrong.

Can you try this on your board please?

Thanks.

Jaya

GNU Source:

>@
=====================================================================>@
Interrupt Vectors
>
>         .code   32
>
>         @ entry points vector
>start:
>         ldr     pc, =error
>         ldr     pc, =error
>         ldr     pc, =error
>         ldr     pc, =error
>         ldr     pc, =error
>         ldr     pc, =error
>         ldr     pc, =error
>         ldr     pc, =error
>
>         .ltorg
>
>@ End of Interrupt Vectors
>@ =====================================================================>
>
>@ =====================================================================>@
Error Scenario
>
>         .code   32
>
>error:
>         @ force reset
>         ldr     r0, =WATCH_DOG
>         mov     r1, #3
>         str     r1, [r0, #0]
>         str     r1, [r0, #4]    @ WDTC = 3
>         mov     r1, #0xaa
>         str     r1, [r0, #8]    @ WDFEED = 0xaa
>         mov     r1, #0x55
>         str     r1, [r0, #8]    @ WDFEED = 0x55
>         b       .
>
>@ End Error Scenario
>@ =====================================================================
HEX Binary: (vectors not check-sum patched)

>:1000000018F09FE514F09FE510F09FE50CF09FE5D8
>:1000100008F09FE504F09FE500F09FE504F01FE580
>:10002000240000000E02A0E30310A0E3001080E50E
>:10003000041080E5AA10A0E3081080E55510A0E3A5
>:08004000081080E5FEFFFFEA55
>:00000001FF
	>Message: 17
>    Date: Thu, 23 Feb 2006 12:30:37 -0000
>    From: "Guillermo Prandi" <yahoo.messenger@yaho...>
>Subject: Re: Bootloader not always invoked after reset with P0.14 low
>
>Hi, Jayasooriah. Indeed the watchdog is the problem. At this stage of
>development I am only using the watchdog to provide a software reset
>function. Apparently this behavior is triggering only after using
>this function. And yes, you are right; the bit should be cleared by
>the external reset.
>
>It looks like this behavior is 'by design' so there is no other
>workaround than switching off the unit.
>
>Guille
	>Message: 8
>    Date: Thu, 23 Feb 2006 23:28:38 -0000
>    From: "philips_apps" <philips_apps@phil...>
>Subject: Re: Bootloader not always invoked after reset with P0.14 low
>
>The bootloader does not look at the RISR register. It looks at the
>WDTOF flag in WDMOD register.
>Even clearing of watchdog flag in user application may not help (if
>timeout is too small) because the bootloader runs before application.
	Send instant messages to your online friends
http://au.messenger.yahoo.com 

I don't understand very well what is it that you want me to test. By 
clearing the watchdog flags my problem went away.

Guille

--- In lpc2000@lpc2..., Jayasooriah <jayasooriah@...> wrote:
>
> Hi Guile,
> 
> I am looking at what appears to be a different manifestation of the 
problem 
> you encountered in that power cycling is required
to recover form a 
lockup 
> in order to transfer control to ISP by pulling
P0.14 low.
> 
> Philips explains this happens can if "timeout value is too
small".  
The 
> user manual seems to say writing anything less
than 0xff will 
result in 
> minimum timeout of PCLK x 256 x 4.
> 
> The test code below then should create the lockup scenario, but it 
does not 
> on my 2292.  I cannot see where I got it wrong.
> 
> Can you try this on your board please?
> 
> Thanks.
> 
> Jaya
> 
> GNU Source:
> 
> >@ 
=====================================================================>
>@ Interrupt Vectors
> >
> >         .code   32
> >
> >         @ entry points vector
> >start:
> >         ldr     pc, =error
> >         ldr     pc, =error
> >         ldr     pc, =error
> >         ldr     pc, =error
> >         ldr     pc, =error
> >         ldr     pc, =error
> >         ldr     pc, =error
> >         ldr     pc, =error
> >
> >         .ltorg
> >
> >@ End of Interrupt Vectors
> >@ 
=====================================================================>
>
> >
> >@ 
=====================================================================>
>@ Error Scenario
> >
> >         .code   32
> >
> >error:
> >         @ force reset
> >         ldr     r0, =WATCH_DOG
> >         mov     r1, #3
> >         str     r1, [r0, #0]
> >         str     r1, [r0, #4]    @ WDTC = 3
> >         mov     r1, #0xaa
> >         str     r1, [r0, #8]    @ WDFEED = 0xaa
> >         mov     r1, #0x55
> >         str     r1, [r0, #8]    @ WDFEED = 0x55
> >         b       .
> >
> >@ End Error Scenario
> >@ 
=====================================================================>

> HEX Binary: (vectors not check-sum patched)
> 
> >:1000000018F09FE514F09FE510F09FE50CF09FE5D8
> >:1000100008F09FE504F09FE500F09FE504F01FE580
> >:10002000240000000E02A0E30310A0E3001080E50E
> >:10003000041080E5AA10A0E3081080E55510A0E3A5
> >:08004000081080E5FEFFFFEA55
> >:00000001FF
> 
> 
> >Message: 17
> >    Date: Thu, 23 Feb 2006 12:30:37 -0000
> >    From: "Guillermo Prandi" <yahoo.messenger@...>
> >Subject: Re: Bootloader not always invoked after reset with P0.14 
low
> >
> >Hi, Jayasooriah. Indeed the watchdog is the problem. At this stage 
of
> >development I am only using the watchdog to
provide a software 
reset
> >function. Apparently this behavior is
triggering only after using
> >this function. And yes, you are right; the bit should be cleared by
> >the external reset.
> >
> >It looks like this behavior is 'by design' so there is no
other
> >workaround than switching off the unit.
> >
> >Guille
> 
> 
> >Message: 8
> >    Date: Thu, 23 Feb 2006 23:28:38 -0000
> >    From: "philips_apps" <philips_apps@...>
> >Subject: Re: Bootloader not always invoked after reset with P0.14 
low
> >
> >The bootloader does not look at the RISR register. It looks at the
> >WDTOF flag in WDMOD register.
> >Even clearing of watchdog flag in user application may not help (if
> >timeout is too small) because the bootloader runs before 
application.
> 
> 
> 
> Send instant messages to your online friends 
http://au.messenger.yahoo.com
>