Post by thread:AD conversion

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) Thanks for your time, Gary Brooks spam_OUTbrooksgTakeThisOuTtdsnet.com

"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 http://hamradio.cmcorp.com/inventory/Inventory.html

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 causes some headaches (see the apnotes on the 14000 ADC). 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 >.....acatalinaKILLspam@spam@gmv.es ----------------------------------------------------------------- Sent from the desk of: Terry Allen Steen, EE engineeringKILLspammarinapower.com 332 McLaws Circle, Ste 111 757-258-8800 (Voice) Williamsburg, Va 23185 757-258-8805 (FAX) ----------------------------------------------------------------- !I AM A WHALE MAIL USER! If you have a large file to send, goto http://www.whalemail.com send them to: mplengineer Give me your account and I will use it also ----------------------------------------------------------------- Visit our web-site: http://www.marinapower.com -----------------------------------------------------------------

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 _____________________________ >From other worlds - http://www.easttimor.com http://www.sudan.com What can one man* do? Help the hungry at no cost to yourself! at http://www.thehungersite.com/ (* - or woman, child or internet enabled intelligent entity :-)) {Original Message removed}