Keiou said:
can somebody tell me the difference between the PIC 16F84 and 16F84A. And which one of the 2 is better for newbies in PICs.
There's a migration document on MicroChip's website at
http://www.microchip.com/download/lit/migrat/30072b.pdf.
There's hardly any difference (but it will run at 20MHz rather than just 10MHz), it's basically just a later silicon revision, StupidDum looks to be mistaken about the 84A having a comparator, there's no mention of it in the migration sheet or datasheet.
Perhaps he's thinking of the 16F628?, this is essentially the replacement for the 16F84 and 16F84A - it has more facilities, is cheaper, and is a pin for pin replacement for them (the only code change required is to turn off it's comparators - if you don't need them).
This was why I picked the 16F628 for my PIC tutorials - internal oscillator (makes it easier to use), 16 available I/O pins (on an 18 pin chip), easily programmed.
For a beginner, use the 16F628 - check my PIC tutorials (complete with hardware designs) at
**broken link removed** or
http://www.winpicprog.co.uk (when the web forwarding service is working.