Lpc2000

I heard that pull ups are needed to run P0.2 & 3 as regular GPIO 
pins, since they are part of the I2C interface. Given the board I'm 
working with...I might not have the luxury to make that hardware 
change.

Isn't there another way (without using pull ups)? How about 
disabling the I2C interface in the Power Control Register (PCONP)? I 
haven't tried it as yet, but if anyone else did, I wouldn't mind 
hearing from you on how it went. 

Thanks in advance,
Leighton

At 01:31 PM 8/9/04 +0000, you wrote:
>I heard that pull ups are needed to run P0.2 & 3 as regular GPIO
>pins, since they are part of the I2C interface. Given the board I'm
>working with...I might not have the luxury to make that hardware
>change.
>
>Isn't there another way (without using pull ups)? How about
>disabling the I2C interface in the Power Control Register (PCONP)? I
>haven't tried it as yet, but if anyone else did, I wouldn't mind
>hearing from you on how it went.

They are open collector pins so there will be nothing to pull them up 
internally. Even if you managed to find a leakage path I'd be leery about 
depending on it.

Robert

" 'Freedom' has no meaning of itself.  There are always restrictions,
be they legal, genetic, or physical.  If you don't believe me, try to
chew a radio signal. "

                         Kelvin Throop, III

> They are open collector pins so there will be nothing to pull them 
up 
> internally. Even if you managed to find a leakage path I'd be 
leery about 
> depending on it.
> 
> Robert
> 

Yeah you're right on that one. Playing with PCONP didn't help much. 
Interestingly, the EINT1 worked on P0.3 (low-active mode) without a 
pullup but I might as well use one just incase. Hopefully P0.2,3,&14 
are the only 3 pins I need to worry about.

Leighton

--- In lpc2000@yahoogroups.com, "Leighton Rowe" <leightonsrowe@y...> 
wrote:
> Yeah you're right on that one. Playing with PCONP didn't help much. 
> Interestingly, the EINT1 worked on P0.3 (low-active mode) without a 
> pullup but I might as well use one just incase. Hopefully 
P0.2,3,&14 
> are the only 3 pins I need to worry about.

Check carefully in the datasheet which pins have internal pull-up, 
internal pull-down, or nothing.  Have just been bitten by that :-(

Karl

--- In lpc2000@yahoogroups.com, "Karl Olsen" <kro@p...> wrote:
> --- In lpc2000@yahoogroups.com, "Leighton Rowe" 
<leightonsrowe@y...> 
> wrote:
> > Yeah you're right on that one. Playing with PCONP didn't help 
much. 
> > Interestingly, the EINT1 worked on P0.3 (low-active mode) without 
a 
> > pullup but I might as well use one just incase. Hopefully 
> P0.2,3,&14 
> > are the only 3 pins I need to worry about.
> 
> Check carefully in the datasheet which pins have internal pull-up, 
> internal pull-down, or nothing.  Have just been bitten by that :-(

Better yet, check the newest manual.  The newest datasheet wrongly 
says that only P1.16-P1.25 have pull-up.  In fact, all of P1 have 
pull-up.

Karl Olsen