Single chip microcomputer "doorbell, AT89S51 Doorbell

Single chip microcomputer "doorbell, AT89S51 Doorbell Keywords: AT89S51, Doorbell Circuit 1. Experimental task When the switch SP1 is pressed, the AT89S51 microcontroller generates "咚" sound from the P1.0 port to the LM386, which is sent to the speaker after enlargement. 2. Circuit schematic 3. System board hardware connection (1. Connect the P1.0 port in the "Microcontroller System" area to the SPK in port in the Audio Amplifier module area; (2. Connect a speaker of 8 euros or 16 o'clock on the SPK OUT port in the "Audio Mode Module" area; (3. Connect the P3.7 / RD port in the "Microcontroller System" area to the SP1 port in the Styard Keyboard area; 4. Programming method (1. We use the microcontroller's fixed time / counter T0 to generate frequencies of 700 Hz and 500 Hz. According to the timing / counter T0, we can get 250Us, so the frequency of 700 Hz should pass through 3 times 250us timing, and the frequency of 500 Hz is 4 Timed 250us. (2. In the design process, only after the SP1 is pressed, the T0 will start working, when T0 is completed, return to the initial state. (3. "" and "咚" sound each takes 0.5 seconds, so timing / counter T0 is required to complete 0.5 seconds, and can be 250Us. 6. Assembly source T5HZEQU 30H T7HZEQU 31H T05SAEQU 32H T05SBEQU 33H Flagbit 00h STOPBIT 01H SP1bit P3.7 ORG 00H LJMP START ORG 0BH LJMP INT_T0 Start: Mov TMOD, # 02H MOV TH0, # 06H MOV TL0, # 06h Setb ET0 Setb EA NSP: JB SP1, NSP LCALL DELY10MS JB SP1, NSP Setb TR0 Mov T5Hz, # 00H Mov t7hz, # 00H Mov t05sa, # 00H Mov t05sb, # 00H CLR Flag CLR Stop JNB STOP, $ LJMP NSP DELY10MS: MOV R6, # 20 D1: MOV R7, # 248 DJNZ R7, $ Djnz R6, D1 RET INT_T0: INC T05SA Mov A, T05SA CJNE A, # 100, Next Mov t05sa, # 00H INC T05SB MOV A, T05SB CJNE A, # 20, Next Mov t05sb, # 00H JB Flag, STP CPL Flag Ljmp next STP: SETB STOP CLR TR0 LJMP DONE Next: JB Flag, S5Hz INC T7Hz Mov A, T7Hz CJNE A, # 03H, DONE Mov t7hz, # 00H CPL P1.0 LJMP DONE S5Hz: Inc T5Hz Mov A, T5Hz CJNE A, # 04H, DONE Mov T5Hz, # 00H CPL P1.0 LJMP DONE DONE: RETI End 7. C language source program #include UNSIGNED Char T5Hz; UNSIGNED CHAR T7Hz; Unsigned int TCNT; Bit STOP; Bit flag; Void main (void) { Unsigned char i, j; TMOD = 0x02; TH0 = 0x06; TL0 = 0x06; ET0 = 1; EA = 1; While (1) { IF (p3_7 == 0) { For (i = 10; I>0; i -) For (J = 248; J>0; J -); IF (p3_7 == 0) { T5Hz = 0; T7Hz = 0; TCNT = 0; FLAG = 0; STOP = 0; Tr0 = 1; WHILE (stop == 0); } } } } Void T0 (Void) Interrupt 1 Using 0 { TCNT ++; IF (TCNT == 2000) { TCNT = 0; IF (Flag == 0) { FLAG = ~ flag; } Else { STOP = 1; Tr0 = 0; } } IF (Flag == 0) { T7Hz ++; IF (t7hz == 3) { T7Hz = 0; P1_0 = ~ p1_0; } } Else { T5Hz ++; IF (T5Hz == 4) { T5Hz = 0; P1_0 = ~ p1_0; } } }, Read the full text

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