With regard to the internal D/A converter of the microcontroller, which use their own D/A converters have a signal needs to be the most economical method. Cygnal Inc. C8051F020 is a powerful up-to-date with the internal D/A converters of the single-chip microcomputer. This paper introduces the look-up table and D/A converters have sinusoidal-shaped method, described in detail in the C8051F020 D/A converter to produce sinusoidal signal circuits and procedures. By modifying the data sheet can produce square wave, triangular wave or any other arbitrary waveform signal.