ADC lcd display help

[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

[kevlar129bp]

Hey Mack,

Quick question. When we're talking about the ADC count based on the sampled voltage,
what happens to the count when it's fractional?
IE:
count = 557.26 ... does this become 557 or 558?
count = 952.76 ... does this become 952 or 953?

I guess I'm just wondering what the "rounding" routine is, if any?

Thanks again,
Chris

[mackrackit]

http://www.picbasic.co.uk/forum/show...7177#post87177

[kevlar129bp]

Thanks for the heads up Mack,

I guess I was a bit confused by this in your ADC scaling tutorial:

Convert this to an 10 bit PIC® resolution.

10 bits ADC = 0 to 1023, 1024 steps.
At 5.0 volts one volt of input will will read 205. (204.6 actually)

Why would that read 205, instead of 204?
Thanks Mack, for helping a newbie trying to understand.

Chris

[mackrackit]

Why would that read 205, instead of 204?

Thanks for catching that and I apologize for the confusion.

I changed the article to

10 bits ADC = 0 to 1023, 1024 steps.
At 5.0 volts one volt of input will will read 204. (204.8 actually)
But we will use 205 for accuracy.
204 * 5 = 1020
205 * 5 = 1025

Hope that clears things up a bit..

[kevlar129bp]

Hey Mack,

I sketched this code in notepad after reading some other posts...
Does it look like I'm on the right track?

ADVal VAR WORD
Quanta CON 489	'VREF/1024 = 5/1024 = .00488 = 489
VoltageDivider CON 70
ADCVolts VAR BYTE
LCDVolts VAR WORD

ADCIN 0,ADVal
	ADCVolts=(ADVal/1000)*Quanta
	LCDVolts=ADCVolts*VoltageDivider
		LCDout $fe, 1
		LCDout $fe, 2,   "CURRENT READINGS ARE"
		Lcdout $fe, $C0, "A/D VDC = ",DEC1 ADCVolts/100,".",DEC2 ADCVolts//100
		Lcdout $fe, $94, "--------------------"
		Lcdout $fe, $D4, "ACTUAL VDC = ",DEC3 LCDVolts/100,".",DEC2 LCDVolts//100

Thanks again for your assistance,
Chris