Sure there is!  It just means more work on your part while writing=20
the software.

The easiest way is to simply calculate each new frequency as you=20
adjust any particular digit's value, then display the new value on the disp=
lay.

dwayne


At 03:04 PM 7/18/2014, David C Brown wrote:
>The problem with that is that the relationship between the 15 bit control
>register and the generated frequency is exponential not linear so that
>there is no simple way to adjust each digit seperately
>
>
>On 18 July 2014 22:16, Dwayne Reid <dwayner@planet.eon.net> wrote:
>
> > If you have the space and input pins available, I'd be using a rotary
> > encoder with push-button.  Encoder starts off by adjusting '1s', with
> > roll-over /roll-under to next digits.  Push the encoder button in,
> > now you are adjusting the '10s' digit.  Same roll-over /
> > roll-under.  Push button in again - now you are adjusting '100s'.
> >
> > And so on.
> >
> > I find it best to dim slightly the digits that you are NOT adjusting
> > or to flash / blink the digit that you ARE adjusting.  Whichever is
> > the most visually appealing / easiest on the eyes.
> >
> > A variation on the above is to have a separate push button to rotate
> > between the selected digit.  The encoder button then becomes the
> > 'Enter' button.  This has the advantage of allowing the digit select
> > button to be labelled as such.
> >
> > The same process can be used to set output level.
> >
> > FWIW - some of the PID temperature controllers use the above
> > technique, except that they use buttons for up and down instead of a
> > rotary encoder.  3 buttons total: up, down, rotate left.  Works just
> > about as well, except that I find using an encoder to be easier to
> > use if I'm trying to "sneak up" on a value.
> >
> > dwayne
> >
> >
> > At 06:17 AM 7/18/2014, David C Brown wrote:
> > >I am building a simple pulse generator using an LTC6903 "synthesiser c=
hip"
> > >and a few TTL chips.  The range will be from about 0.1Hz to 68MHz and =
the
> > >frequency is set, geometrically, by a 15 bit control word.  I  will be
> > >using a PIC16F87 to control the synthesiser and drive a display.
> > >
> > >My problem is how to set the frequency by hand  using the minimum pane=
l
> > >hardware.   I need control at the finest level, stepping the control
> > >register by one but also need to be able to make large frequency shift=
s
> > >quickly, perhaps stepping the register by 2^10
> > >
> > >I have studied this for some time and come up with several solutions, =
non
> > >of them entirely satisfactory, but I would appreciate, in the first
> > >instance, suggestions which are not influenced by my thinking.


--=20
Dwayne Reid   <dwayner@planet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
(780) 489-3199 voice          (780) 487-6397 fax
www.trinity-electronics.com
Custom Electronics Design and Manufacturing

--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.