SignalGeneratorSD based on AD9833 Module, August 2020

Added a new cool feature: Stepped Sweep Generator - the frequency is varied in a range defined by values set in Ch#0 (start of the range) and Ch#1 (end of the range) with signal settings of Ch#0 and discrete steps of 0,1 of a current running frequency (kind of logarithmic steps).
Frequency value steps either up or down from the start of the range depends on what channels' frequency is larger. Frequency is changed discretely every 250 mSec (can be changed at compilation).
The running Stepped Sweep Generator cycle is indicated by SWEEP word that replaces the current Chanel number and a blinking cursor at the end of a frequency value. The feature can be activated for Ch#0 only and uses its signal settings.
While running, can be cancelled by short press and hold of OK button. When the end of the range is reached, it pauses for 3 sec and switches back to Ch#0 settings.
Sweep generators are commonly used to test the frequency response of electronic filter circuits. Read more about Sweep Generator in Wikipedia.
All code is well commented and easy to understand.