>Hi All,
>
>I am facing a big challenge and before I will go ahead I would like to
>ask anybody who has a good idea.
>The solution not need to be cost effective.
>I need to generate square wave with close to 50% duty cycle,
>but quartz precision.
>The frequencies are :   400Hz      -   4KHz   10Hz steps
>                                        4KHz       --   40KHz  100Hz steps
>                                        40KHz     --   400KHz 1000Hz steps
>                        400KHz     --   4MHz 10000Hz steps
>
>I really appreciate any idea.
>
>Thank You,
>
>Peter     ( schupet@dvp.com )

Perhaps it is overkill for your application but yiu might want to take a look at one of the Numerically Controlled Oscillator (NCO) chips.  An application utilizing the HARRIS HSP45102 was described in the December 1997 (issue 89) and January 1998 (issue #90) editions of Circuit Cellar INK, it even uses a PIC16C54.  The in this application it is crystal controlled and should be easily adapted to your requirements.

HARRIS is at:
http://www.harris.com/

HSP45102 data and Applications info is at:
http://www.semi.harris.com/data/fn/fn2/fn2810/index.htm

Circuitcellar INK is at:
http://www.circuitcellar.com

cheers,

Phil

Philip Starbuck
(909) 792-7917

"There are three principal ways to lose money.  Wine, women, and engineers.  While the first two are more pleasant the third is by far the more certain."
                                                -- Baron Rothschild
                                                        ca. 1860