Arduino NANO + 19 resistors = A DDS signal generator

This is the schematics and the prototype...

It generates signals (very nice to 1300 hz, acceptable to 10khz) using a N - 2N resistor ladder DAC.

It has been designed to be plugged on 7 contiguous pins (GND, D2, ... , D7).

Using 150ohm resistors its internal resistance of 150ohm. It generates 0 to Vcc (actually 63/64 of Vcc) waves on an open circuit, 0 to Vcc/2 on a 150 ohm Load

The source code of the Arduino's sketch is:.