Forums

Disabled JTAG = Disabled EINT0

Started by timothymarknorton December 11, 2006
I am having a problem when trying to disable the JTAG interface on an
LPC213X. I have a pulldown resistor attached to P0.31. On my JTAG
interface, I apply 3.3V to P0.31 and everything works fine. What I
have noticed, is that when my JTAG interface is not connected (p0.31
pulled low) I no longer recieve EINT0 interrupt on P0.16. Can anyone
tell me if they have seen this behaviour? Or am I missing something?

An Engineer's Guide to the LPC2100 Series

How did you setup your PINSEL regs? JTAG is controlled by those also.

Chris.
----- Original Message -----
From: timothymarknorton
To: l...
Sent: Monday, December 11, 2006 12:33 PM
Subject: [lpc2000] Disabled JTAG = Disabled EINT0
I am having a problem when trying to disable the JTAG interface on an
LPC213X. I have a pulldown resistor attached to P0.31. On my JTAG
interface, I apply 3.3V to P0.31 and everything works fine. What I
have noticed, is that when my JTAG interface is not connected (p0.31
pulled low) I no longer recieve EINT0 interrupt on P0.16. Can anyone
tell me if they have seen this behaviour? Or am I missing something?
P0.31 is an output only pin and doesn't appear to be related in any way to
P0.16. Can you tell us what your value of PINSEL1 and what the respective
IODIR values for P0.16 and P0.31 are?

Andy

-----Original Message-----
From: l... [mailto:l...]On Behalf Of
timothymarknorton
Sent: 11 December 2006 20:34
To: l...
Subject: [lpc2000] Disabled JTAG = Disabled EINT0
I am having a problem when trying to disable the JTAG interface on an
LPC213X. I have a pulldown resistor attached to P0.31. On my JTAG
interface, I apply 3.3V to P0.31 and everything works fine. What I
have noticed, is that when my JTAG interface is not connected (p0.31
pulled low) I no longer recieve EINT0 interrupt on P0.16. Can anyone
tell me if they have seen this behaviour? Or am I missing something?
After looking at the errata:

Note.2:Port pin P0.31 must not be driven low during
reset. If low on reset the device behaviour is
undetermined.

Basically I am seeing undetermined behaviour. Parts
of my system are not always working is P0.31 is low
after reset.

--- Andrew Berney wrote:

> P0.31 is an output only pin and doesn't appear to be
> related in any way to
> P0.16. Can you tell us what your value of PINSEL1
> and what the respective
> IODIR values for P0.16 and P0.31 are?
>
> Andy
>
> -----Original Message-----
> From: l...
> [mailto:l...]On Behalf Of
> timothymarknorton
> Sent: 11 December 2006 20:34
> To: l...
> Subject: [lpc2000] Disabled JTAG = Disabled EINT0
> I am having a problem when trying to disable the
> JTAG interface on an
> LPC213X. I have a pulldown resistor attached to
> P0.31. On my JTAG
> interface, I apply 3.3V to P0.31 and everything
> works fine. What I
> have noticed, is that when my JTAG interface is
> not connected (p0.31
> pulled low) I no longer recieve EINT0 interrupt on
> P0.16. Can anyone
> tell me if they have seen this behaviour? Or am I
> missing something?
>
>
> [Non-text portions of this message have been
> removed]

____________________________________________________________________________________
Need a quick answer? Get one in minutes from people who know.
Ask your question on www.Answers.yahoo.com
--- In l..., "timothymarknorton"
wrote:
>
> I am having a problem when trying to disable the JTAG interface on an
> LPC213X. I have a pulldown resistor attached to P0.31. On my JTAG
> interface, I apply 3.3V to P0.31 and everything works fine. What I
> have noticed, is that when my JTAG interface is not connected (p0.31
> pulled low) I no longer recieve EINT0 interrupt on P0.16. Can anyone
> tell me if they have seen this behaviour? Or am I missing something?
>

Hi Timothy,

the errata of the LPC2138 says:
"Port pin P0.31 must not be driven low during reset. If low on reset
the device behaviour is undetermined."

You have that pull-down...

Karl