[sdiy] New 16F18xx enhanced mid range PICs

[Richie Burnett]

Hi Tom,

Thanks for the info on these new additions and the summary of Synth related
benefits!

Have you looked at some of the 18F series?  The PIC18F452 comes to mind as a
device that has 40MHz clock input, 8x8 hardware multiply and proper
add-with-carry instructions.  I don't think it has the shaddow registers and
extra memory indirect pointer though.

-Richie,

> Hi All,
>
> I've been playing with some of the new Microchip 16F PICs. They're identifiable
> because their part numbers all start 16F1xxx.
> The two chips I've looked at specifically are the 16F1824 and the 16F1847.
>
> There are various fairly minor changes, but overall they make significant
> improvements to both speed and memory usage.
>
> 1) Low voltage versions - You can get the chip in an LV version to run on 3.3V
> if you want
> 2) 32MHz top speed - a big boost from the previous 20MHz, more than 50% faster
> in raw power terms.
> 3) Extra instructions - many of these help shorten the sequences required for
> common tasks. This saves both program memory and processor cycles.
> For example: ADDWFC - Finally, an "add with carry" instruction!! This turns a
> 24+24-bit addition from a 10 instruction sequence into a 6 instruction sequence.
> Also included are better handling of indirection registers with pre/post
> inc/decrement and more versatile bit-shifting instructions,
> 4) Two indirection registers. This also speeds things up since you don't have to
> set them up so often. You can use one for writing samples to memory and one for
> reading them out, for example.
> 5) Shadow registers for automatic context saving for interrupt routines. This is
> another simple thing, but a big improvement. Saving and restoring context can
> easily use up twenty instructions in an interrupt routine. This saves all that
> work, shortening interrupts significantly.
> 6) Lots of extra peripherals for no more money - more ADC, more PWM, more SPI,
> more UARTs, etc etc. This is useful, but not really that important. The range of
> previous chips was so wide, you could always find one with all the things you
> need.
>
> In short, I'm impressed with the new chips. The additions are thoughtful -
> someone has looked at what people really use and added a few key details that
> make life much easier/faster, without implying great changes.
>
> If there'd been a "multiply" as well, it might have been the killer chip for a
> quid.
>
> Tom
>
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