Does Pull UP affects the volatge on pin....?

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hi there....,
This may be a very basic question....or a silly one to be posted on this forum....it'll be good know its answer...we are getting 4.35V on a I/O pin...our supply voltage is 5.07V. We are not using regulator.
PULL UP value is 10k...AVR Mega 32,Port used is PORTA.

...hgaurav 'n' bdhanu :oops:

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Yes, the pullup affects the voltage on the pin.
Think about it, a 10k resistor attached to v+, the other side of it is attached to the pin. What do you have connected to the port pin? That could be loading it down.

All the best on your quest
Jim

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Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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Normally, with no load, you would expect only a 100mV or so (in a 5V system) between the output level and the supply. The pull up will raise the LOW level slightly and ought to make the HIGH level even closer to Vcc.

So, I would look at what else is connected to that pin.

Another Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

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Another Jim :lol:
Good point. I missed that one myself.

One thing the OP noted is that they are using an unregulated supply.

OP:
What else do you have connected to the power supply?

What is the voltage on the VCC pin of the AVR?

Why an unregulated supply?

The list of questions can go on..............

All the best on your quest
The other jim :wink:

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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How is the pin configured? Input? Output? What is it connected to?

The difference between the supply and the I/O pin voltage is about a diode drop, but that may be coincidence.

Yet another Jim

(Do we have a quorum yet?)

Your message here - reasonable rates.

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To all the Jim's:

The answers to our questions we will never know, untill the OP doth he show..... :mrgreen:

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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But even still, a logic high of 4.35 volts in a 5 volt system isn't anything to worry about.

The Mega32 data-sheet states that the minimum logic high output voltage is 4.2 volts for a 5 volt system.

While the logic high output of this controller is only 150mV from the minimum specification, it is still within specification.

If this controller was on my bench, I'd simply be taking note of this fact for future reference and then be moving on.

You can avoid reality, for a while.  But you can't avoid the consequences of reality! - C.W. Livingston

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Oh no! A heathen non-Jim has invaded this thread!

There could be many reasons for this reading, but, without further information from the OP, speculation is pointless.

Jim

Your message here - reasonable rates.

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JimW52 wrote:
Oh no! A heathen non-Jim has invaded this thread!

Ah yes! That would be me! :lol:

You can avoid reality, for a while.  But you can't avoid the consequences of reality! - C.W. Livingston