[beagleboard] How can I omit pullup resister.

2014-03-05 Thread masterplays555
Hi, forks! 
I got BBB and start enjoying.

I wonder How to work pullup pinmode at input in software.
 http://beagleboard.org/Support/BoneScript/pinMode/

I want to pull up P8_31(GIPO_10) as Input 、but it effect noting.
 1.b.pinMode("P8_31", 
b.INPUT_PULLUP
);
 2.b.pinMode("P8_31", 
b.INPUT, 
7, 'pullup');
Both are in same result and P8_31 never pulluped.
Of course  when I connected a 
10Kohm resister between P8_31 and VDD3V3 , It pulluped and work fine.
I want to omit this resister.

Many chips (PIC & AVR & etc..) has software pullup mode and no need to 
connect extra resister.  But In BBB It doesn't work?? Always need extra 
resister?

My BBB's info:
*Your board is connected!*
BeagleBone Black rev 00A6 S/N 4613BBBK1318 running BoneScript 0.2.2 at 
192.168.7.2

I want some help, Please.

Thanks.

P.S.
I know in BBB it is limited 4mA or 6mA for GPIO current.
My question is total current limitation in BBB. Is there any limitation for 
total current?

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Re: [beagleboard] How can I omit pullup resister.

2014-03-05 Thread Gerald Coley
Check the datasheet. The pull up may or may not be small enough depending
on what it has to pull up. The current is the max the pin can do. In other
words, that is who large the pull up actually is. Turning on all the weak
pullups isn't going to strain the total current of the power supply which
is the real limiting factor. And there aren't that many pullups
you can turn on any way as most of the signals are used for other things on
the board..

Gerald


On Wed, Mar 5, 2014 at 3:38 PM,  wrote:

> Hi, forks!
> I got BBB and start enjoying.
>
> I wonder How to work pullup pinmode at input in software.
>  http://beagleboard.org/Support/BoneScript/pinMode/
>
> I want to pull up P8_31(GIPO_10) as Input 、but it effect noting.
>  1.b.pinMode("P8_31", 
> b.INPUT_PULLUP
> );
>  2.b.pinMode("P8_31", 
> b.INPUT,
> 7, 'pullup');
> Both are in same result and P8_31 never pulluped.
> Of course  when I connected a
> 10Kohm resister between P8_31 and VDD3V3 , It pulluped and work fine.
> I want to omit this resister.
>
> Many chips (PIC & AVR & etc..) has software pullup mode and no need to
> connect extra resister.  But In BBB It doesn't work?? Always need extra
> resister?
>
> My BBB's info:
> *Your board is connected!*
> BeagleBone Black rev 00A6 S/N 4613BBBK1318 running BoneScript 0.2.2 at
> 192.168.7.2
>
> I want some help, Please.
>
> Thanks.
>
> P.S.
> I know in BBB it is limited 4mA or 6mA for GPIO current.
> My question is total current limitation in BBB. Is there any limitation
> for total current?
>
>  --
> For more options, visit http://beagleboard.org/discuss
> ---
> You received this message because you are subscribed to the Google Groups
> "BeagleBoard" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to beagleboard+unsubscr...@googlegroups.com.
> For more options, visit https://groups.google.com/groups/opt_out.
>

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