Note frequency /HZ half period /us(N)
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● 1do 262 1908 # 1do # 277 1805
●2RE 294 1700 # 2RE # 3 1 1 1608
Low 3mi3301516 # 3mi # 3401470
●4fa 349 1433 # 4fa # 370 1350
●5SO 392 1276 # 5SO # 4 15 1205
●6LA 440 1 136 # 6LA # 466 1072
●7si 494 10 12 # 7si # 524 0954
Zhong1do5230956 #1do # 5540903
Clock 2RE 578 0842 #2RE# 622 0804
Zhong Sanmi 659 0759 # Sanmi # 682 0733
Zhong 4FA 698 07 16 #4FA# 740 0676
Medium-sized 5SO 784 0638 #5SO# 83 1 0602
Clock 6LA 880 0568 #6LA# 932 0536
7SI 988 0506 #7SI# 1046 478。
Height1do1046478 #1do #1109451.
Gao 2Re1175426 # 2Re #1245402
Gao 3mi1318372 # 3mi #1356368
Gao 4fa1397358 # 4fa #1480338
Gao 5SO1568 319 # 5S0 #1661292
Gao 6la1760284 # 6la1865268
Gao 7SI 1976 253 #7SI# 2066 242
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("#" means semitone, which is used to raise semitone) */
/* - */
# include & ltreg52.h & gt// contains header files, which generally do not need to be changed. The header file contains definitions of special function registers.
# Define uint unsigned integer
# Define uchar unsigned characters
sbit spk=p 1^2； //Define the horn port
Unsigned int I；; //Define global variables
Uchar table[ 14]={ // the initial value of the timer corresponding to the alto scale.
0xfc，0x44，// 1
0xfc，0xb6，//2
0xfd，0x09，//3
0xfd，0x34，//4
0xfd，0x82，//5
0xfd，0xc8，//6
0xfe，0x06 //7
};
/******************************************************************/
/* Delay function statement */
/******************************************************************/
Void delayms(unsigned int xms) // millisecond delay
{
uint i，j；
for(I = xms； I>0; I-)
for(j = 125； j & gt0; j-)；
}
Void init() // timer initialization function
{
TMOD | = 0x 0 1； //Timer working mode, Timer 0 is used for timing.
TH0 = Table [0]; //Timer scale 1 corresponds to the initial value, which is 0xfc high and 0x44 low.
TL0 = table[ 1]；
ET0 = 1； //Timer 0 allows
EA = 1； //Open host interrupt
}
/******************************************************************/
/* Main function */
/******************************************************************/
Master ()
{
init()； //Timer initialization
while( 1)
{
for(I = 0； I<7; I++) // Play 7 scales in a loop.
{
TR0 = 1； //Start Timer 0, start counting, and generate the horn driving frequency.
Delems (500); //Each scale lasts about the playing time.
TR0 = 0； //Stop timing
delayms( 1000)； //The horn stops working, and the intermittent time is about 1s, which can be changed.
}
}
}
Invalid timer 0 () interrupt 1 // timer interrupt function
{
TH0 = table[I * 2]； //Decimal digits 1234567 corresponds to the high value of the initial value of the timer.
//table[i*2] means the number 02468101214 in the table[] array.
TL0 = table[I * 2+ 1]； //table[i*2+ 1] indicates the value of1357911315 in the table[] array.
SPK = ~ SPK； //When the timing is up, the horn level is reversed to realize frequency drive.
}