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ADC calculations in the voltmeter project

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sahu

Member
i am working a voltmeter project.it is based on 16f676. but don't understand ADC calculations in the voltmeter project . i see also Electronic Circuits it is not working properly. and c lang. also
 

MikeMl

Well-Known Member
Most Helpful Member
The A/D input to a Pic is usually ratiometric with respect to the Vdd pin, meaning if it is a 10 bit A/D, it will read out 1023 (2^10-1) when the analog input is the same as Vdd. That means you have to know what Vdd actually is; 5V is not good enough. You have to know if it is 4.87V or 5.04V.
 

Sceadwian

Banned
Does that particular pic not have an internal voltage reference? I'm used to AVR's which although they can use VCC as a voltage ref also generally have an internal bandgap voltage source of around 2.54 volts, so long as the VCC voltage is above the internal circuitry's threshold for regulation. (not sure what that is off the top of my head) the ADC results will be unaffected.
 

sahu

Member
The A/D input to a Pic is usually ratiometric with respect to the Vdd pin, meaning if it is a 10 bit A/D, it will read out 1023 (2^10-1) when the analog input is the same as Vdd. That means you have to know what Vdd actually is; 5V is not good enough. You have to know if it is 4.87V or 5.04V.
dear sir
thank for replly, pl more exaplane and example....
 

MikeMl

Well-Known Member
Most Helpful Member
They say it better than I can...
 

Noggin

Member
Don't contact him, ask for more help on the forum. If you PM him, then the other forum visitors don't benefit from your question and his response. :)
 

sahu

Member
Don't contact him, ask for more help on the forum. If you PM him, then the other forum visitors don't benefit from your question and his response. :)

[ask for more help on the forum.] it is my mean. not PM to him
 
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