At 12:07 10/19/2001 -0400, Drew Vassallo wrote:
>>>How can you expect to get a pulse resolution of .00012 if your instruction
>>>cycle time is ** .0002 ** at 20 MHz?
>>
>>The instruction cycle time is ** 0.00000005s ** for a 20Mhz clock! and
>>with both
>>the post
>>scale and pre-scale set to 16 you get a TMR2 resolution of 0.0000128s!
>
>The quadrature timing for instruction pipelining in the PIC line of products
>is a 4:1 ratio.  That means a 1/20MHz * 4 = cycle time per instruction.
>
>20MHz cycle time = 200ns = .2us

Now besides black holes and other esoteric things I just wanted to set a
few things around unit modifiers and decimal numbers straight... :)

(The 200 ns basic instruction cycle time is correct for 20 MHz clock.)

200 ns = 0.2 us = 0.0002 ms = 0.0000002 s


Some interesting material every engineer should have seen at least once
(but also quite interesting for hobbyists :) can be found at the NIST
<http://www.nist.gov/>:
- International System of Units <http://physics.nist.gov/cuu/Units/index.html>
- Guide for the Use of the International System of Units (SI)
<http://physics.nist.gov/Pubs/SP811/sp811.html>

ge

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads