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upward migration

 
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jack11
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upward migration
PostPosted: Fri Apr 30, 2004 7:27 pm     Reply with quote

I'm considering moving up from the 16F parts to the 18F parts. Any body had any experiences doing this? Is it worth the cost of a new compiler, reworking old code, etc.


thanks
Haplo



Joined: 06 Sep 2003
Posts: 659
Location: Sydney, Australia

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PostPosted: Fri Apr 30, 2004 7:34 pm     Reply with quote

It depends from what chip to what chip you are going to migrate. Recently I updated a project from PIC16F877 to PIC18F442 with almost no effort at all. The only thing you need to do is to fix any #byte or #bit definitions you might have as well as some very minor changes depending on your code.
It is definitely worth the update because the PIC18 chips give you more memory, more modules (timers,...), hardware multiplication, more interrupt sources, priority interrupts,...
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PostPosted: Sat May 01, 2004 5:52 am     Reply with quote

I'm moving from the 16f877 also. the 18f sure looks like a better part.
thanks for the input
Ttelmah
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PostPosted: Sat May 01, 2004 6:04 am     Reply with quote

Anonymous wrote:
I'm moving from the 16f877 also. the 18f sure looks like a better part.
thanks for the input

If you are running short of space, this is the way to go. Also (assuming the existing board is built for something like a part at 10MHz), you have the option of using the 'H4' fuse, and running the processor at four times the clock rate.
There are however some 'caveats'. The 18F, has a lot more registers that have to be saved when entering an interrupt, and at the same clock rate, as a result displays _worse_ interrupt latency. Though the chip, apparently has the 'nice' ability to have dual priority interrupts (with a high priority event able to interrupt a low priority handler), this is still in many cases unuseable, because of a fault in the silicon, which can result in instructions being skipped if the high priority event is from an asynchronous source....
The family has some nice features, and is a good way of going if you require more raw processor power, RAM or ROM.

Best Wishes
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