ADC lcd display help

[kevlar129bp]

Hello all,

I am finally able to re-visit an old project of mine and am in need of a bit of assistance.
I've got a 16F886 up and going with one exception... the ADC.
I've got a DC source I'm monitoring with 10 bit res. on AN0.
The details:
DC can swing from 0-350 vdc.
This runs through a 70:1 scaler and is clamped to 5.1 vdc.
So at 350 vdc, max scaled voltage will be 5 vdc. (350/70)
...
This is where I get way confused
Can one of you fine folks explain how to determine the ADC "count" based on my 0-350 vdc?
and
How to convert the ADC counts back to the 0-350 vdc in order to display it on an lcd?
...
Thank you all,
Chris

[Charles Linquis]

10 bit A/D count = 1023 when Vin = Vref
12 bit A/D count = 4096 when Vin = Vref

[Charles Linquis]

Correction:

12 bit A/D count = 4095 when Vin = Vref

[kevlar129bp]

Thanks Charles,

I think I grasp that concept.
350/1024 = .3418 ... so for every .3418 volt change at the 350 side of things, there is a "count" change.
Therefore, if we start with, say:
165 vdc
...through the voltage scaler to the ADC in:
165/70 = 2.3571 vdc
VRef(5.1)/1024 = .004883
2.3571/.004883 = 482.7115 <<<<<<<<<<<<<<<<<<< The ADC "count" would be 482?
(ADC count * 4883 * Scaler ratio) / 10000
(482*4883*70) / 10000 = 16475.242<<<<<<<<<<<<<<<<< 16475 is the "high voltage"?
...for the lcd:
LCDOut 16475/100,".",16475//100," VDC"
"164.75" <<<<<<<<<<<<<<<<<<<<<<<<< Where did I go wrong in not getting "165"?

I am probably confusing myself more than I'm helping.
Would love a quick tutorial from one of you knowledgeable folks.

Thanks again,
Chris

[mackrackit]

At the risk of confusing you more...
http://www.picbasic.co.uk/forum/cont...Sensor-Scaling

[kevlar129bp]

Thanks Mack,

Funny you point out that thread... That's the one I've been racking my brain over.
I'll take another look though.

Chris