AVR-Chat

Why don't you try ATMEGA8.

--- On Wed, 8/5/09, Yingdan <yingdanh@gmail.com> wrote:

From: Yingdan <yingdanh@gmail.com>
Subject: [AVR-Chat] 16f88 vref problem
To: AVR-Chat@yahoogroups.com
Date: Wednesday, August 5, 2009, 9:41 AM






 




    
                  Hello,



I am using VREF+ and AVss for a potentiometer. Below is my setting:



status_rp = 01   	-- select bank 1

CVRCON = 0b_1110_0110

ANSEL  = 0b_0001_1001

ADCON1 = 0b_0010_0000	-- VREF+/AVSS

status_rp = 00		-- select bank 0



The VREF+ pin gives ~1.2v and I can get the reading 0 - 255 in the range of 0 - ~1.2v. The problem is the reading is unstable. When I rotate the shaft from high to low, and low to high, I got different readings for a specific position. From high to low, I got a relative bigger reading and from low to high, I got a much smaller reading for the similar position. 



I have no idea how to fix the problem. Can anyone help to take a look at my CVRCON and ADCON1 registers since I am not confident with them, or offer any help about what might be wrong?



Your help is highly appreciated,

Yingdan 




 

      

    
    
	
	 
	
	








	


	
	

[Non-text portions of this message have been removed]