AVR-Chat

Place a capacitor between Aref and ground (the analog ground).

The accuracy of the conversion is better than .5%, but depending upon your
VCC accuracy, your absolute accuracy won't be so good.  At room temperature
most +5v regulators are pretty good, but you definitely won't get the
accuracy over temp without an external, calibrated reference.

-----Original Message-----
From: Andrew Lim [mailto:normaxcite@yahoo.com]
Sent: Monday, November 01, 2004 9:50 PM
To: AVR-Chat@yahoogroups.com
Subject: [AVR-Chat] ADC accuracy in ATmega8535


Hi there,



I'm using ADC interrupt mode in my prototype board. Everything is running
now but I'm facing accuracy problem. Can someone help me? I need my accuracy
to be +/- 0.5%.



1. I have my AVCC connected to Vcc.

2. Aref not connected.

3.Set free running mode

4.REFS1 = 0 , REFS0 = 0  (Choosed AVCC with external cap at Aref) -> what if
I dun have caps coupled between AVCC and Aref? Will it affect the accuracy?





Thanks.



Andrew





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