AVR-Chat

Hi Jeff,

 

What results are you seeing from the ADC with this code?

 

What voltage have you got on Vref?

 

What else have you tried?

 

Dave.

 

From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf
Of Jeff Blaine AC0C
Sent: 21 January 2010 17:47
To: AVR-Chat@yahoogroups.com
Subject: [AVR-Chat] Vref on ATTiny861a

 

  

I am having a tough time getting this chip to respond to any other ADC
voltage reference than the default AVcc.

The code snip is really simple... Below, using the MakroC Pro compiler,
however the results seem to be the same if I do the same using ASM
instructions instead of their bit-level defines.

I must be overlooking something. It seems so simple, driving me nuts that
it's not working right. I have used the same compiler and basic code to get
a mega328 to work. 

Appreciate any suggestions the group may have.

Thanks/jeff

REFS0_bit = 1; // 001 invokes external Vref as ADC reference
ADEN_bit = 1; // enable adc
ADSC_bit = 1; // start conversion
while(adsc_bit);
lb=ADCL; // get lower byte
ub=ADCH; // get upper byte
adc_rd0 = (256*ub) + lb; // build number





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