about caps and crystals

[masoud]

hi guys!!

i've some basic questions! but didn't find any proper answer anywhere!!

in microcontroller, what's the effect of AMOUNT of two caps which connect to pins of crysta?
i mean why we use 30pF caps, or 22pF? WHY NOT 27, 100 OR...

and IF the frequency which we apply to the micro, decrease or increase by any condition, or by accident, what is the result? how effect on the micro operation and its cycle-machin?

(( and a non relative question!! except plastic, what kind of materials can be used in making body of micro?! ))

TAHX ALOT[;)]

[trax]

The values of capacitors depend on the frequency of the crystal you use. You can see the table of capacitor values for different crystal values in Datasheet of PIC16F84A which you can download from http://www.microchip.com" onclick="window.open(this.href);return false;.

The result in frequency drift will cause your micro to execute instructions faster or slower

[Smjesko]

@masoud, try this:

Google -> " materials for chip housing " <Enter> and then browse the links.

Enjoy reading

[trax]

http://www.lmgtfy.com/?q=materials+for+chip+housing" onclick="window.open(this.href);return false;