How to select Vref?

[sid2286]

Hi,

I'm using PIC18F4520 for my project. my input for ADC is 200mV to 1.2V.
now i want to give vref to my microcontroller. It has to pin RA3/AN3/
VREF+ and RA2/AN2/VREF-/CVREF pins.

So how do i give Vref? should i apply 1.5v to only VREF+ and keep open VREF- or should i ground the Vref- pin??

Please help.

Rgds,
Sid

 

[GreenGiant]

it should be you only have to connect the 1.5 to the +Vref but connecting ground to the -Vref should not have any negative affects, this is drawing from experience with Arduino's NOT PIC's so I'm not 100% sure if they work the same

 

[BobK]

In PICs you can separately specify whether Vref+ and Vref- are internal or external. You would leave the Vref- internal, which connects it to ground and frees that pin for other uses. Also check the datasheet for the minimum Vref. I think 1.5V is going to be too low.

Bob