Re: [avr-gcc-list] measuring uC supply voltage

[antony]

E. Weddington a écrit :

> On 22 Oct 2004 at 19:03, JAMIE MORKEN wrote:
>
>  
>
> > Hi all,
> >
> > I am trying to figure out the best way to measure the 5V supply voltage for an 
> > atmega128.  I am using the 5V supply as the ADC reference voltage.  The problem 
> > I am seeing is when the 5V supply droops, the reference voltage will also 
> > droop.  For other sensors I need to use the 5V reference voltage.  Any ideas on 
> > how to solve this?  Is it possible to switch to the internal 2.5V reference 
> > while the 5V external reference is still hooked up?  Thanks,
> >
> >    
>
>
> I don't know about being able to switch over, but FYI, the internal reference is not all that 
> accurate. I would suggest using an external voltage reference device, perhaps a 2.5V ref. 
> Unfortunately, I don't know a part number off hand (I'm more of a software engineer, not a EE).
>
> HTH
> Eric
>
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> .
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>  

Try this

   http://space.auburn.edu/CHS/mag/LM185-ADJ.pdf

Regards
Antony