Huh. Good idea. Thanks for the new perspective. It pays to re-examine your
habits from time to time.
Norman
--- In l..., "misterhershel" wrote: >
> --- In l..., "Michael" wrote:
> >
> > I need the groups help desperately. Regarding the LPC2468 does anyone know
what we should do with unused GPIO pin? Do we ground them, add a pull up or down
resistor, or just leave them alone?? I have searched the 700+ page user's
manual, the NXP website, our group and the Internet and can not find a valid
answer to this question. I have sent an email to NXP support and have not
received a response. I would greatly appreciate any and everyone's
input.
> >
> > Thank you!!
> > I normally leave a few as inputs, then ground them. It makes it a lot easier
to flood a well grounded copper ground plane under the chip.
>
> -Hershel
>
Reply by Marcelo Richter●January 20, 20102010-01-20
To LPC work, you dont need to worry with them...
But I suppose you are having EMI problems with your board.
Then, to reduce this, a good practice is to "fix" pins at some level (by
programming them as outputs or activating pull-ups).
But this alone doesnt solve the problem...
Marcelo
> -----Original Message-----
> From: l... [mailto:l...] On Behalf Of > Michael
> Sent: ter-feira, 19 de janeiro de 2010 16:00
> To: l...
> Subject: [lpc2000] LPC2468
>
> I need the groups help desperately. Regarding the LPC2468 does anyone know what > we should do with unused GPIO pin? Do we ground them,
add a pull up or down > resistor, or just leave them alone?? I have searched
the 700+ page user's manual, the > NXP website, our group and the Internet and can not
find a valid answer to this > question. I have sent an email to NXP support and
have not received a response. I > would greatly appreciate any and everyone's
input.
>
> Thank you!!
>
>
>
>
>
>
>
Reply by misterhershel●January 20, 20102010-01-20
--- In l..., "Michael" wrote: >
> I need the groups help desperately. Regarding the LPC2468 does anyone know
what we should do with unused GPIO pin? Do we ground them, add a pull up or down
resistor, or just leave them alone?? I have searched the 700+ page user's
manual, the NXP website, our group and the Internet and can not find a valid
answer to this question. I have sent an email to NXP support and have not
received a response. I would greatly appreciate any and everyone's
input.
>
> Thank you!!
>
I normally leave a few as inputs, then ground them. It makes it a lot easier to
flood a well grounded copper ground plane under the chip.
-Hershel
Reply by Michael Frazier●January 20, 20102010-01-20
Thanks Leon,
But my concern is what about the time period before the firmware is
loaded, I believe they all become inputs by default, I am trying find out if
there is something that I should do physically on the board to cover this time
period.
Thanks Again!!
________________________________
From: l... [mailto:l...] On Behalf Of Leon Heller
Sent: Tuesday, January 19, 2010 2:28 PM
To: l...
Subject: Re: [lpc2000] LPC2468
On 19/01/2010 19:00, Michael wrote: > I need the groups help desperately. Regarding the
LPC2468 does anyone know what we should do with unused GPIO pin? Do we ground
them, add a pull up or down resistor, or just leave them alone?? I have searched
the 700+ page user's manual, the NXP website, our group and the Internet
and can not find a valid answer to this question. I have sent an email to NXP
support and have not received a response. I would greatly appreciate any and
everyone's input.
As with all MCUs, making them outputs is the best option.
Leon
Reply by Nick●January 19, 20102010-01-19
Hi Micheal,
On many of my boards, what I do is leave the unused IO pin disconnected and
configure the unused pin as an output. Seems to work fine.
Nick
________________________________
From: Michael
To: l...
Sent: Tue, January 19, 2010 2:00:14 PM
Subject: [lpc2000] LPC2468
I need the groups help desperately. Regarding the LPC2468 does anyone know what
we should do with unused GPIO pin? Do we ground them, add a pull up or down
resistor, or just leave them alone?? I have searched the 700+ page user's
manual, the NXP website, our group and the Internet and can not find a valid
answer to this question. I have sent an email to NXP support and have not
received a response. I would greatly appreciate any and everyone's
input.
Thank you!!
Reply by eqh2●January 19, 20102010-01-19
--- In l..., "Michael" wrote: >
> I need the groups help desperately. Regarding the LPC2468 does anyone know
what we should do with unused GPIO pin? Do we ground them, add a pull up or down
resistor, or just leave them alone??
I am new to the LPC also but in my experience you should never leave a GPIO pin
floating. But, many (if not all) GPIO pins have an internal pull up that could
be enabled for any unused pins so you may not need external connections to pull
ups or pull downs.
-Dan
Reply by Michael Frazier●January 19, 20102010-01-19
Thanks everyone!!
I will take advantage of the PINMODE defaults and then make them all outputs
as soon as possible. This should cover it...I believe that if it did not cover
the issue, someone else in the group would be having problems by now. Thanks
again everyone for the quick responses, I appreciate the help very much!
THANKS!!!
________________________________
From: l... [mailto:l...] On Behalf Of Norman
Sent: Tuesday, January 19, 2010 3:05 PM
To: l...
Subject: [lpc2000] Re: LPC2468
Hi Michael,
The LPC2468 has on-chip pull-ups and pull-downs that can be selected via the
PINMODE0 to PINMODE9 registers. At power up, the pins have the on-chip pull-up
enabled. (Chapter 9, section 4 in the version of the LPC24xx User Manual I
have.)
So, the pins are not in an undefined state prior to your software taking
control.
I'm with Leon, though, and prefer to set unused pins as outputs. If you do
that, make sure the PINMODEx values are consistent with your choice setting the
output high or low. No point in incurring the extra power consumption of having
your output pull in the opposite direction from an on-chip pull-up or pull-down.
There's also a PINMODE option to have no on-chip pull-up or pull-down.
Hope that helps.
Norman
--- In l..., Michael Frazier
wrote: >
> Thanks Leon,
> But my concern is what about the time period before the firmware is loaded, I
believe they all become inputs by default, I am trying find out if there is
something that I should do physically on the board to cover this time period.
>
> Thanks Again!!
>
> ________________________________
> From: l...
[mailto:l...] On Behalf Of Leon Heller
> Sent: Tuesday, January 19, 2010 2:28 PM
> To: l...
> Subject: Re: [lpc2000] LPC2468
>
> On 19/01/2010 19:00, Michael wrote:
> > I need the groups help desperately. Regarding the LPC2468 does anyone know
what we should do with unused GPIO pin? Do we ground them, add a pull up or down
resistor, or just leave them alone?? I have searched the 700+ page user's
manual, the NXP website, our group and the Internet and can not find a valid
answer to this question. I have sent an email to NXP support and have not
received a response. I would greatly appreciate any and everyone's
input.
>
> As with all MCUs, making them outputs is the best option.
>
> Leon
>
Reply by Michael●January 19, 20102010-01-19
I need the groups help desperately. Regarding the LPC2468 does anyone know what
we should do with unused GPIO pin? Do we ground them, add a pull up or down
resistor, or just leave them alone?? I have searched the 700+ page user's
manual, the NXP website, our group and the Internet and can not find a valid
answer to this question. I have sent an email to NXP support and have not
received a response. I would greatly appreciate any and everyone's
input.