Finally some update on AVR DDS3 signal generator. Circuit is practically done and PCBs are made. I decided to go with two microcontrollers on board to make it more functional. One microcontroller Atmega328P is gonna be dedicated to user interface and signal generator control. Second Atmega88 is gonna be used for signal generator only. This will give un-interruptable signal output while changing parameters or simply doing signal sweeps. Simple keypad should be convenient for entering frequency values and menu navigation.