This paper compares the design methods,advantages and weaknesses of several kinds of laser harps,and introduces the circuit design of a kind of laser harp.This includes the laser harp circuit block diagram,the chip selection of peripheral circuits.The emphasis is the introduction of two kinds of realization modes of music chip YM-6100 keyboard matrix: MCU interruption mode and hardware decoding mode.This Paper also introduces the theories of auto-playing music for MCU to control music chip YM-6100,and the c...