The resolution of the display is less than resolution of the frequency generator chip. It is intended as a rough indication of frequency, the final setting being done with an external frequency counter. (rather like the scale on an old fashioned instrument) On 19 July 2014 01:31, Dwayne Reid wrote: > Sure there is! It just means more work on your part while writing > the software. > > The easiest way is to simply calculate each new frequency as you > adjust any particular digit's value, then display the new value on the > display. > > dwayne > > > At 03:04 PM 7/18/2014, David C Brown wrote: > >The problem with that is that the relationship between the 15 bit contro= l > >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 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 > chip" > > > >and a few TTL chips. The range will be from about 0.1Hz to 68MHz an= d > 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 > panel > > > >hardware. I need control at the finest level, stepping the control > > > >register by one but also need to be able to make large frequency > shifts > > > >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. > > > -- > Dwayne Reid > Trinity Electronics Systems Ltd Edmonton, AB, CANADA > (780) 489-3199 voice (780) 487-6397 fax > www.trinity-electronics.com > Custom Electronics Design and Manufacturing > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 __________________________________________ David C Brown 43 Bings Road Whaley Bridge High Peak Phone: 01663 733236 Derbyshire eMail: dcb.home@gmail.com SK23 7ND web: www.bings-knowle.co.uk/dcb --=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 .