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pic18f2580 oscillator config

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New Member
Hi guys , i m working on pic18f2580 using 8 mhz crystal oscillator with 22 Pf capacitor, but my some programs are not working , now looking over the data sheet in oscillator configuration topic , it says
If HS is
selected, it is possible that the gain of the
oscillator will overdrive the resonator.
Therefore, a series resistor should be
placed between the OSC2 pin and the
resonator. As a good starting point, the
recommended value of RS is 330Ω.
so i want to ask for which oscillator it is required is it for crystal oscillator , i m also posting my schematics for pic18f2580 system . also please verify my settings.



Well-Known Member
HS is good for 8MHz, so are the 22pF caps. I've never needed a resistor with my crystals.

PS your PIC has an internal 8MHz oscillator with about a 1% accuracy. If you use it does your program run?

You could try XT as your setting.

What programmer are you using?
Last edited:


New Member
thanx BLUE, but data sheet says for operation above 3.5mhz it is better to use Hs mode, im using universal programmer , my programs are working on other systems i dont know waht the wrong i m doing , can u sort out any possible thing
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