AD9833 module is a 0-12.5Mhz waveform generator with integral 25MHz crystal oscillator, the output frequency is set by the SPI controlled divider of the AD9833. A DAC shapes the sine and triangle waveforms, amplitude is 600mV. Squarewave amplitude is 5V. The Arduino drives the AD9833 using SPI. The Frequency in the AD9833 is selected by 28 bit value which gives about 0.1Hz resolution, the Arduino 32 bits integer limit allows accuracy of about 0.1%.
Pushbutton WAVEFORM selects between Sine, Triangle (300mV) or Squarewave (5V). Digit pushbutton selects the digit to set, UP pushbutton increments the digit.
The LCD of 16x2 display the High and Low Frequencies. The 16x2 LCD module has to be HD44780 compatible.