“A signal generator is a very useful piece of test gear. This one uses an AD9833 module and an Arduino Nano - that’s all, not even a PCB. You can optionally add an OLED display. The AD9833 can gererate sine, triangle and square waves from 0.1 MHz to 12.5 MHz - the software in this project is limited to 1Hz to 100kHz.
There have been other Instructables using an Arduino and an AD9833, here and here. This is simpler and can be used as a sweep generator. Sweep generators help test the frequency response of filters, amplifiers and so on. Unlike the other Instructables designs, this does not include an amplifier or amplitude control but you could add them if you wanted.”