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1999\03\18@113455 by

Hello all,

Novice here trying to do an A/D conversion and then feed that out to the
LCD. I am using a PIC17c756 with C language. I can get the initial
conversion but I am having trouble getting that result into a sensible
format to a 4-digit LCD. What conversions do I need to do ...etc.
I would appreciate any help / advice as to how to proceed. (What I am
basically doing is building a varying voltmeter from 0-5 volts)

Gary Brooks
brooksgtdsnet.com

2000\01\18@102330 by
I am attempting to convert the resistance(or converted voltage)  from a
thermister to a digital signal.  I do not understand what voltage
corresponds to what binary number.

Thanks Richard

"Anderson, Richard L." wrote:

> I am attempting to convert the resistance(or converted voltage)  from a
> thermister to a digital signal.  I do not understand what voltage
> corresponds to what binary number.
>
> Thanks Richard

Well, an 8 bit A-D converts 0-5 volts into 0x00 - 0xFF.
That is about .0196 volts per bit.

--
Thomas C. Sefranek  WA1RHP
ARRL Instructor, Technical Specialist, VE Contact.
http://www.harvardrepeater.org

part 0 16 bytes
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The PIC 14000 uses constant current sources to  scharge a cap. The ammount
of clock pulses required for the cap voltage to equal your input voltage is
the value of the input voltage. This is alot different than typical ADC and

Terry

At 10:19 AM 1/21/2000 +0100, you wrote:
>   I'm thinking to use a little PIC, like the 12C509, to obtain a  measure
>of an analogic signal with 12 bits of resolution. I don't want to use  any
>kind of ADC circuit. Does anyone know if this thing is possible?, (may be
>measuring the charging time of a capacitor).   Alfredo Catalina
>acatalinagmv.es
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On Fri, 21 Jan 2000, Alfredo Catalina wrote:

> I'm thinking to use a little PIC, like the 12C509, to obtain a measure
> of an analogic signal with 12 bits of resolution. I don't want to use
> any kind of ADC circuit. Does anyone know if this thing is possible?,
> (may be measuring the charging time of a capacitor).

http://www.dattalo.com/technical/software/software.html

and in particular:

http://www.dattalo.com/technical/software/pic/a2d.asm

Scott

Consider sigma Delta conversion.
See Scott Dattalo's website for a PIC implementation.
Would work OK on 12C509
Essentially this is a form of tracking PWM .
Accuracy of 12 bits is pushing things but should be possible with care.

Russell McMahon
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