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has portb.3 a special condition?

 
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ferkar



Joined: 14 Jul 2007
Posts: 38

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has portb.3 a special condition?
PostPosted: Mon Feb 11, 2008 7:47 am     Reply with quote
hi everybody:)

i would like to ask you a simple question. my 16f877 and pc communicate over rs232 channel. i made a visual basic interface to command to pic. when i send the data,that is 15, 3 leds are turned on while the last one , the msb in nibble , dis not turn on.

i was wondering that is portb.3 need for a pull-up resistor or something like that to give an output?

please help about this...
bye
ckielstra



Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands

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PostPosted: Mon Feb 11, 2008 7:59 am     Reply with quote
From note 3 on Table 3-3 of the PIC16F87x datasheet:
Quote:
3: Low Voltage ICSP Programming (LVP) is enabled by default, which disables the RB3 I/O function. LVP
must be disabled to enable RB3 as an I/O pin and allow maximum compatibility to the other 28-pin and
40-pin mid-range devices.
Solution: Add #fuse NOLVP to your program.
ferkar



Joined: 14 Jul 2007
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thanks for answer
PostPosted: Mon Feb 11, 2008 10:07 am     Reply with quote
i ll try it ..
ferkar



Joined: 14 Jul 2007
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thanks indeed...
PostPosted: Wed Apr 02, 2008 7:59 am     Reply with quote
the problem was solved ...
thanks
PCM programmer



Joined: 06 Sep 2003
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PostPosted: Wed Apr 02, 2008 8:31 am     Reply with quote
This is in the CCS FAQ. Bookmark this page:
http://www.ccsinfo.com/faq.php

It's in this section:
Quote:

Input/Output

Why isn't PortB, pin 3, working?
rnielsen



Joined: 23 Sep 2003
Posts: 852
Location: Utah

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PostPosted: Wed Apr 02, 2008 12:41 pm     Reply with quote
One problem is that many people attempt to 'dive' into writing code without fully reading all of the documentation. I, myself, am guilty of this from time-to-time. I really dislike reading and have a tendancy to realize that I need to read the various spec. sheets fully before I attempt to use new parts.

It's an unfortunate part of lazy human nature. Wink

Ronald
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