Progrmming PIC16F84A

williB said:

That the 16F84A need external ossicalator like RC...??? What about 16F628??

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yes i believe they are the same in that respect

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Nigel Goodwin said:

williB said:

That the 16F84A need external ossicalator like RC...??? What about 16F628??

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yes i believe they are the same in that respect

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But the 628 has the HUGE advantage that it has an internal 4MHz RC oscillator, which allows it to have up to 16 free I/O pins on an 18 pin chip (whereas the 84 only has 13). It also makes layout far easier, no messing about with crystals and capacitors - and the internal 4MHz oscillator is accurate enoguh for most purposes.

I might also mention the 16F819, basically a 628 but with internal 10 bit A2D, and an 8MHz (but selectable for other speeds) internal oscillator.

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amady said:

So how i want to design the external oscillator using R and C. I think i don't want to use cristal in order to reduce my costing... what the suitable value for R and C??? Before this i'm try to use R=330K and C=220pF...

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Nigel Goodwin said:

The datasheet gives the formula for calculating them, but you could try those values and see what it runs at.

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