28课单片机音乐程序设计(国外英语资料).docVIP

28课单片机音乐程序设计(国外英语资料) The use of single-chip (or single board) music is probably one of the radio enthusiasts interested in problems. In this paper, starting from the basic experiment of single-chip microcomputer, the design principle of the music program is discussed, and some specific examples are given for reference. Experiment of basic pronunciation of SCM We know that the sound frequency range of about tens to thousands of Hertz, if can use the program to control the single machine of a line of high level or low level, in the mouth of the line will be able to have a certain frequency square wave with certain frequency, the sound of horns can, if the use of delay procedures the duration of control of high and low level, can change the output frequency, thus changing the tone. For example, to produce an audio signal for 200HZ, enter the horn as shown in Figure 1 (if it is a temporary experiment, the speaker can be connected directly to the P1 port): Among them, subroutine DEL is a delay subroutine, and when R3 is 1, the delay time is about 20us, the delay constant is stored in R3, and the 200HZ audio frequency is 1/200 seconds, that is 5ms. Thus, when the P1.4 high or low duration is 2.5ms, or the time constant of R3 takes 2500/20=125 (7DH), the 200HZ tone can be emitted. Type the program into the learning machine and continue to modify the R3 constant to feel the change in pitch. In music, each note corresponds to a definite frequency. Table 1 gives the notes and their corresponding time constants at the C tone. According to the constants provided in Table 1, the reader can send his 16 decimal code to R3 and practice it repeatedly. According to table 1, the notes can be played. Thats not enough. One must accurately control the tempo of a piece of music, that is, the duration of a note. Note the rhythm, we can use timer T0 to control, send different initial value, can produce different timing time. Just as the tempo of a song is 94 beats per minute, or 0.64 beats