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arunb
Joined: 08 Sep 2003 Posts: 492 Location: India
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How to use RA4 as an output pin in 16F648A mcu |
Posted: Wed Oct 04, 2006 9:21 am |
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Hi,
I am not able to use the RA4 as an output pin in a 16F648A mcu, kindly explain how I can do this ???
thanks
arunb |
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Ttelmah Guest
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Posted: Wed Oct 04, 2006 9:25 am |
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Look at the pin diagrams in the data sheet.
RA4, functions as an output, _but has no pull up FET present_. Hence _you_ must pull any line attached up externally with a resistor etc..
Best Wishes |
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Guest
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Posted: Wed Oct 04, 2006 7:16 pm |
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Hi,
Actually, RA4 has an output FET, but it is open-drain. You solution, however, is correct. |
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Ttelmah Guest
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Posted: Thu Oct 05, 2006 9:19 am |
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Read what I say.
It has no _pull up_ FET. The normal outputs have two FETs, one a P type, connected to the Vdd rail, and the other an N type, connected to Vss. Both are wired as 'common source' devices (with their sources connected to their respective supply rails). A4, has the P type (pull up) FET omitted.
Best Wishes |
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