PIC16F872 oscillators

Hello,

I'm new here and on PICs too. I would like to know if the PIC16F872 has an internal oscillator ?

I saw these modes :

• LP Low Power Crystal
• XT Crystal/Resonator
• HS High Speed Crystal/Resonator
• RC Resistor/Capacitor

If I choose the RC osc mode, do I necessarily need to make a RC oscillator or it will take by default an internal clock (if it has one) ?

Is the RC osc a good choice for my LED cube project ?

And if I configure it as a RC osc. How do I know the frequency its running ?

See page 98 for Oscillator mode on the 16F872 datasheet.

I know its a lot a question at once but I would really appreciate.

Thanks a lot !!!

Weepet

No, it doesn't have an internal oscillator as it's quite an old chip. Switch to the 16F883 and you will have an 8MHz int osc and more peripherals as well.

Mike.

Thanks, but if we assume that I only got this PIC.

How would I know the frequency my RC oscillator give to my PIC ? Hz meter ?

If you look at page 142 figure 15-7 of the data sheet it will all become clear.

Mike.

Not sure, at my page 142 there is a figure 14-10 : AD/ conversion and the only time I see talking about RC mode is

Standard(F) 2.0 4.0 6.0 µs A/D RC Mode
Extended(LF) 3.0 6.0 9.0 µs A/D RC Mode

You should give up right now. If you're not capable of finding figure 15-7 then you have no chance whatsoever of programming anything.

Mike.
P.S. the page number is in the bottom left hand corner.

Hahahaha ....

I think your a little bit impatient ...

First, I can read a datasheet.
Second, I know how to find a page number.
Third, I didn't had the updated datasheet (section 15 wasn't done yet)
Fourth, you should never say to someone to give up ....

Fifth, I see that with a 3.3k resistor, a 20pF capacitor and a 5 V Vdd, I can reach 3.5MHz

And if I follow the datasheet, I can see that

Recommended values: 3 kΩ ≤ REXT ≤ 100 kΩ
CEXT > 20p

So if I'm right 4Mhz is unreachable with a RC Oscillator ?

Thanks for your patience

Weepet.

Sixth, when someone tries to help you, you should make just a teeny weeny effort to help yourself before criticizing.

Mike.

Yes you did help me but one of your post was not really necessary.

Thanks anyway

Weepet.