I had this AD9850 unit some time waiting to test it.
I used an ARDUINO UNO with LCD Keypad shield
And a rotary encoder.
Many HAM 's already build receivers and tranceivers based on this fantastic AD9850 as VFO.
With this AD9850 building a rock stable VFO became a piece of cake!
The ARDUINO website shows many projects with this AD9850
But I could not find a sketch that fitted my setup 100%.
I used the rotary encoder improved interrupt sketch as first base
by Simon Merrett / Oleg Mazurov / Nick Gammon rt Steve Spence
First only down count worked I had the encoder at pin 1 and 2 not 2 and 3 since those pins are shifted 1 position on the board that tricked me.
Also the Vcc had to be connected to this encoder.
Only enabling the internal pull-up R's on the pins 2 and 3 showed missing pulses.
Had to adapt some things
The main loop was only a 1 time loop in fact in the original sketch
The LCD Keypad shield uses the pins 4 5 6 7 8 9 for the LCD and AD0 for the keys
But AD1 2 3 4 5 and D2 and D3 where left free
ATmega328 free AD inputs can be used as GPIO real nice
Some struggle to get the encoder to work. At first only rubbish came out.
But then it worked stable pulsing up and down and functions to the main loop for displaying and controlling the DSS VFO where added.
10Hz to 51 MHz! steps adjustable 1Hz ! to 100kH or 1 Mhz
all as you please!
and I could tune calibrate it to my K3 that is very stable and precise at frequency.
this is the sketch it works but needs more features