Prob osc with PIC16f876 20 sp

[kris]

Hello,

I use a pic 16f876 20sp with oscillator 20 mhz and 2 capacitors 33 pf and
my prog is:

Define osc 20

loop: PORTB.0=0
Pause 500
PORTB.0=1
Pause 500
Goto loop
End

Why my prog doesn't work? I don't understand because the same prog with pic 16f876 4sp with oscillator 4 mhz and 2 capacitors 33 pf works ( lineless
Define osc 20)
If you know with probleme please help me!

Thank you Kris

[Melanie]

33pF seems high at 20MHz... remove the Caps and see if it works then.

[Bruce]

Are you setting oscillator selection bits in config word for HS?

A 20MHz crystal requires a higher drive level output on osc2. Make sure you
set config word for HS instead of XT.

[kris]

I changed my caps by 10 pF and my pic work correctly.

I have another question, How you choose yours caps ?
thank you

[Melanie]

If I told you Kris, everybody would start doing it...

Aw, all right, just between you and me - I read the PIC Datasheet!