PIC Questions

[Bill the arcstarter]

It was written:
>For us novices, could you briefly explain what a PIC is exactly and 
describe
>(manufacturer / model / part#) the board you mention.  Also a brief
>explanation of why you would prefer the PIC board to the HC11 (assuming 
you
>could find an HC11 board).

PICs are made by Microchip Technologies, url = http://www.microchip.com 
.  They are usually small cheap simple RISC-ish processors which include 
onboard ram, timers, uarts, etc.  Not all models have all options.

Most PICs have no external address/data us, but are instead chock full 
of i/o lines which can be used for all sorts of things.

I've been fooling with these critters for a couple of years, and I can 
only summarize them by saying that "They are neat"!

For the beginner, the typical part to choose would be the 16C84 or 
16F84.  These guys have some eeprom (64 bytes) on the inside and the 
program memory is completely flash.  Typical home-style development 
involves "crash and burn", where the chip is pulled from the target 
board, reprogrammed (takes about 20 secs) and reinserted for a try.  
This part also has an on-board timer, interrupts, watchdog, low power 
sleep mode, 13 i/o lines (any combo of input/output), anti-pilfer code 
protection, in-circuit programming and other stuff like that.

The assembly language is a bit cryptic, but not bad for a person already 
experienced in that particular art.  All instructions (except for 
branches) execute in exactly 1 clock cycle.  "C" and/or BASIC 
development systems are available but I don't know where.  You can clock 
the little beggars up to (I think) 10-20 Megahertz.  Not bad for a $6 
part!  Digikey sell them too.

Anyone out there using any decent in-circuit emulators, other than 
microchip's $3000 Pro-Mate system?  I'm looking for something to help me 
develop for other non-flash parts, and I hate the UV-erase technique...  
There was some sort of ICE-PIC box - which would supposedly let you 
program and run in-circuit at realtime clock rates.  Anyone seen or 
using one of these systems?

Of course the Atmel AVRs are rather equivalent and fully flash... :)

Thanks.
-Bill



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