Hi,
I'm new to pic controller. I connected -Vref at port A.2 and +Vref at port A.3 and Analog input at Port A.5. Then the out put will be store where. Thanks in advance.

 

hi,

If you are OK with 10 bit resolution, there is no need for an external A2D convertor with a 16F877A.

What is the volatge you want to convert.? volts etc...

__________________
Eric " Good enough is Perfect "
I will NOT answer PM's requesting technical help, please use the Forum
PIC tutorials: Nigel's www.winpicprog.co.uk/ Bill's: www.blueroomelectronics.com/

 

Hi,
Thanks for your suggestion. In my application I need a 8 bit resolution.

 

In which case you are perfectly fine with the 16F877A, it can be easily configured to allow simple 8 bit readings.

My tutorials explain how to use the analogue inputs.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

hi,
What voltage are you trying to convert.?
The description of the -/+Vref is puzzling.

__________________
Eric " Good enough is Perfect "
I will NOT answer PM's requesting technical help, please use the Forum
PIC tutorials: Nigel's www.winpicprog.co.uk/ Bill's: www.blueroomelectronics.com/

 

-Vref=-2v and +Vref=6v

 

You can't have a negative Vref, 0V is as low as you can go, you also can't go above Vdd (usually 5V).

This is pretty universal with all ADC's.

DC shift the signal so it fits within the permitted limits.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

hi,
Post a diagram showing the PIC adc input connection.
You dont seem to understand the PIC's specification.

__________________
Eric " Good enough is Perfect "
I will NOT answer PM's requesting technical help, please use the Forum
PIC tutorials: Nigel's www.winpicprog.co.uk/ Bill's: www.blueroomelectronics.com/