adc problem of pic

[neelam29]

hi frndz
m working on adc of pic16f877. m using two analog inputs .

when i give inputs at both the pins i.e (either 5 volts to both or ground to both)then the value comes correct but if i give input to one of the pin as 5 volts and other as ground then the adc shows absurd value.

the one on which i give 5 volts shows me 348 decimal and the other one shows 0 .

please help me how can i make it correct

 

[Nigel Goodwin]

Try reading my PIC tutorial about analog inputs!.

It explains what's almost certainly your problem - which is too high a source impedance feeding the input. You can either provide a lower source impedance, or add a suitable delay after switchign channels.

 

[PIC Coder]

Nigel Goodwin

Dear sir,

I want to know about you. What you do and where are you from. When first I see your name I confused with the name Nigel Gardner, I have book written on PIC C for CCS C. But you are Goodwin NOT Gardner. Can you please tell me some thing about you.

Bye

 

[Nigel Goodwin]

Re: Nigel Goodwin

Dear sir,

I want to know about you. What you do and where are you from. When first I see your name I confused with the name Nigel Gardner, I have book written on PIC C for CCS C. But you are Goodwin NOT Gardner. Can you please tell me some thing about you.

You can check my websites, another one is http://www.lpilsley.co.uk.

 

[PIC Coder]

Thanks Nigel

Thanks Nigel for the link.