Unused Ports

[sandy wilson]

I know this has been answered somewhere else but I've done a search and can't find it. What is the best way to leave unused ports on the 16F877. Set them as outputs?, inputs?, Outputs and loaded with a resistor tied high/low?

Any suggestions

Thanks

Sandyw
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Original Post ID: 13572

[Sherpa Doug]

:=I know this has been answered somewhere else but I've done a search and can't find it. What is the best way to leave unused ports on the 16F877. Set them as outputs?, inputs?, Outputs and loaded with a resistor tied high/low?
:=
:=Any suggestions
:=
:=Thanks
:=
:=Sandyw

I generally leave them open as outputs. That way they are not susceptable to noise and are available as diagnostic outputs or for future expansion. If you have space you might even run them to test points.

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Original Post ID: 13574

[Neutone]

:=:=I know this has been answered somewhere else but I've done a search and can't find it. What is the best way to leave unused ports on the 16F877. Set them as outputs?, inputs?, Outputs and loaded with a resistor tied high/low?
:=:=
:=:=Any suggestions
:=:=
:=:=Thanks
:=:=
:=:=Sandyw
:=
:=I generally leave them open as outputs. That way they are not susceptable to noise and are available as diagnostic outputs or for future expansion. If you have space you might even run them to test points.
:=

Microchip has some application notes reguarding low power operations that cover this topic. Inputs (floating) consume more power.
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[R.J.Hamlett]

:=I know this has been answered somewhere else but I've done a search and can't find it. What is the best way to leave unused ports on the 16F877. Set them as outputs?, inputs?, Outputs and loaded with a resistor tied high/low?
:=
:=Any suggestions
:=
:=Thanks
Either set them as inputs, and provide an external resistor pull up/down, or set them as outputs.
You do not want a pin to float. The section of the chip data sheet, dealing with the 'sleep mode', covers the best way to set pins.

Best Wishes
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Original Post ID: 13583

[PCM programmer]

:=I know this has been answered somewhere else but I've done a search and can't find it. What is the best way to leave unused ports on the 16F877. Set them as outputs?, inputs?, Outputs and loaded with a resistor tied high/low?
:=
------------------------------------------------------

I set them as outputs, and set them low. That way, they're
not floating inputs, which could cause noise inside the PIC,
and as low-level outputs, they can't source any current if
something accidently touches the pins (such as a scope ground
lead, a screwdriver, etc.)

If you want some PIC archives other than this group, go here:
<a href="http://groups.google.com/advanced_group_search" TARGET="_blank">http://groups.google.com/advanced_group_search</a>
Set the group to comp.arch.embedded.piclist
(or to get more articles, set it to comp.arch.embedded.*)
Then in the box for phrases, put: unused inputs
There are several opinions on it, but I like my method best,
for the reasons given above.
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Original Post ID: 13589

[sandy wilson]

Thank you everbody for your help.


Sandy
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Original Post ID: 13600