ADC Vrefh and Vrefl setting

[Chullaa]

Hi i am using PIC16F877A, trying to interface Analog Accelerometer, which gives output between 0.85V to 2.45V.
**broken link removed**
The Question is
How can i change ADC referance voltage (defaul: VSS and VDD) to 2.45V and 0.85. I read in some thread that it should be atleast 2.5V difference in range.
Any clue?

Regards
Umair

 

[wp100]

Hi,

You use ADCON1 on the 877A to select external Vrefs.

See Tahmids excellent blog ADC #6 , but also have a good look at the rest of his ADC sections.
https://www.edaboard.com/blog/1574/

If you understand the adc system you might find you can simply use the default internal +5v ref without using external lower voltages.