PORTA.4 problem in PIC16F84A ?

[iugmoh]

I don't know why porta.4 in pic16f84a can't be high , all other pins can go low or high but porta.4 only low.
How I can solve this software or hardware ?

here is my code :


trisa=0
porta=%11111

main:
goto main
end

[Acetronics2]

Hi,

Have a look to the '84 Datasheet ...

Porta.4 is Well Known to be an OPEN COLLECTOR output ...

You can use an external Pull up resistor, if you do not need too much current @ highstate.

Alain

[iugmoh]

Oky I know this and I put a pull up resistor but this pin can't drive led so how I can do this ?

[Melanie]

There's more than one way to power a LED - and that pin can SINK a LED quite happilly. Please study the PICs Datasheet and/or SEARCH the forum...

http://www.picbasic.co.uk/forum/showthread.php?t=562

[iugmoh]

Thanks Melanie for your details information
but I don't know what is the objective for making this pin is the only pin who is open drain !