AVR-Chat

Depending upon your source, the internal A/D capacitors retain a certain 
amount of the voltages you are sampling. Try sampling a grounded signal 
(or the internal ground) before sampling your POT.

Yingdan wrote:
>  
>
> 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
>
> __._,_.__