Hi Michael,

It looks strange! The PB5 input pin is connected to the TxD of RS232
port via a 100K resistor. While debugging, when I had a logic probe on
PB5 the characters started echoing. Then I went through the data sheet
to find out what is the difference between other ports and PB5. Later
I added another 100K from PB5 to Vcc and it all worked!

Regards,

-- 
Chetan Bhargava
Web: http://www.bhargavaz.net
Blog: http://microz.blogspot.com


On 5/9/05, Michael Rigby-Jones <Michael.Rigby-Jones@bookham.com> wrote:
> Chetan,
> 
> Did you find out why a pullup resistor was required on an input pin?
> I'm guessing the pullup was required for whatever cricuit was driving
> the pin?
> 
> Regards
> 
> Mike
>

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist