Adder

The NCOx adder is a full adder, which operates independently from the system clock. It adds the value of the increment value to the accumulator on each NCO clock pulse. The adder takes the value in the accumulator and then adds the increment value. The result is placed back in the accumulator. The accumulator value will roll over and any value beyond the 1,048,575 will get placed as the starting value in the accumulator.

This can be reset if desired by writing a zero to the accumulator. This is typically done within the interrupt service routine if that is enabled on the NCO module.