Along with the technical fast development, monolithic integrated circuit's application is day by day common. At present, the MCS-51 series's 8051 monolithic integrated circuits also obtained the widespread application in the industry examination domain, this monolithic integrated circuit system design application monolithic integrated circuit control technology, the monolithic integrated circuit knowledge union which the semester studied for the core basis in has designed the electric piano system which by 51 monolithic integrated circuits set of monolithic integrated circuits controlled. This system majority of software and hardware may soften by the software routine the substitution, the electric circuit are succinct, the ease of operation, the performance are good The musical note in fact has the fixed cycle signal. First expands group of small keyboards (this design take 4×4 keyboard as example, may demand must expand), this pressed key often operates the pressed key for the triggering type. Pressed key's input signal gives AT89C51YI a timer through at89C51 P1 mouth input (for example T1) to control, outputs the square-wave periodic signal on the P3.4 foot, (easiest to use LM368) makes the audio frequency small power amplifier enlargement output through piece of LM324 the signal to deliver the speaker again (this design only then to use in monolithic integrated circuit experiment box's buzzer) finally to send out music.
key word: AT89C51; LM324; Matrix keyboard line scan; Electric piano
