how to make a variable frequency genarator using arduino

hi friends  in this blog  lets build a variable frequency generator using arduino
the main feature of this genarator is you can see the output frequency in lcd screen and also you can convert its output to triangular wave or sine by adding rc integrator circuit.the maximum frequency of this genarator is 2mhz
Materials Required
 Arduino Nano
 16*2 Alphanumeric LCD display
 Rotary Encoder
 Resistor(4.7K,220ohm)
 Perf board

Circuit diagram

Completed circuit on pcb

code

pwm library