I have tried using a zener off my VCC. I also used an adjustable power supply (external from VCC). The main thing I'm trying to do is get full range (10) bit on a 1.7v reading. However Its so jumpy its not worth the effort. As far as your Item 2 is concerned I have to disagree. When using the internal ref. and properly set up clock I can get rock solid readings from the AtoD. ----- Original Message ----- From: To: Sent: Monday, December 23, 2002 11:16 AM Subject: Re: [PIC]: > 1. You may have noise on your reference voltage. What voltage are you > powering your Vref with? > > 2. You should never trust an analog reading as far as you can throw it. > Use some kind of software filtering like median filtering especially if > the result needs to be precise. > > > > > -- Lawrence Lile > > > > > > Andy Kunz > Sent by: pic microcontroller discussion list > 12/21/02 07:58 AM > Please respond to pic microcontroller discussion list > > > To: PICLIST@MITVMA.MIT.EDU > cc: > Subject: Re: [PIC]: > > > What size pot? You need to meet the impedance requirements. You also > should have a big cap on it, especially with newer chips I've found. > > Andy > > At 01:57 AM 12/21/02 -0500, you wrote: > >I have been using PIC chips for a while and it seems that every time I > use > >the VRef option when working with AtoD ports on the mid and high end > chips I > >cant get the readings to settle down. I get a rough range of +-5 on my > >readings. I I tie the Vref to VCC or disable this option it works ok. > > > > > >Is there any hard and fast rules for using this option. > > > >-- > >http://www.piclist.com#nomail Going offline? Don't AutoReply us! > >email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics