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!!
LPC2468
Started by ●January 19, 2010
Reply by ●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
>
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 ●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
>
> 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 ●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!!
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 ●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
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 ●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
>
> 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 ●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!!
>
>
>
>
>
>
>
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 ●January 22, 20102010-01-22
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
>
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
>
