Vref in 12F615

[tripper269]

Hi,

I am working with PIC12F615 and trying to use 1.2V ref voltage for ADC. But unable to find proper Syntax. I looked in to the header file but couldn't find it.
Need Help

[Ttelmah]

Because it can't be done.....

The internal Vref, cannot be used as the ADC Vref.
The ADC, can only have it's Vref, from the supply rails, or from the Vref input pin. Quote from data sheet:
"The ADC voltage reference is software selectable to
either VDD or a voltage applied to the external reference
pins."
The minimum Vref supported by the ADC, is 2.2v, with 2.5v minimum for full accuracy.
The reference, as well as being too low in voltage, cannot supply the current needed by the ADC.

You can _read_ the reference as an input to the ADC, but not use it as Vref.

Best Wishes