99 second single-chip micrometer design, 99s Timer

99 second single-chip micrometer design, 99s Timer Keywords: AT89S51, horse watch circuit 1. Experimental task (1. At the beginning, "00" is displayed, and then the time is started after the SP1 is pressed. (2. Press SP1 in the second time to stop. (3. After the 3rd, press SP1, timing is zero. 2. Circuit schematic 3. System board hardware connection (1. Connect the P0.0 / AD0-P0.7 / AD7 port in the "MCU system" area to the "four-circuit static digital display module" area on any of the A-H ports; requirements : P0.0 / AD0 corresponds to a, P0.1 / AD1 corresponding to B, ..., P0.7 / AD7 corresponds to H. (2. Connect the P2.0 / A8-P2.7 / A15 port in the "MCU system" area to any of the A-H ports in the "four-circuit static digital display module" area; : P2.0 / A8 corresponds to a, P2.1 / A9 corresponding to B, ..., P2.7 / A15 corresponds to H. (3. Connect the P3.5 / T1 in the "MCU system" area to the SP1 port in the "Separate Keyboard" area; 4. Block diagram T0 interrupt service block diagram 5. Assembly source Tcntaequ 30h TCNTBEQU 31H SECEQU 32H KeycnTequ 33h SP1bit P3.5 ORG 00H LJMP START ORG 0BH LJMP INT_T0 Start: Mov Keycnt, # 00H Mov sec, # 00H Mov A, Sec Mov b, # 10 Div AB Mov dptr, # TABLE MOVC A, @ a + dptr MOV P0, A Mov A, B Mov dptr, # TABLE MOVC A, @ a + dptr MOV P2, A Mov TMOD, # 02h Setb ET0 Setb EA WT: JB SP1, WT LCALL DELY10MS JB SP1, WT Inc keycnt Mov A, Keycnt CJNE A, # 01H, KN1 Setb TR0 MOV TH0, # 06H MOV TL0, # 06h Mov tcnta, # 00H Mov tcntb, # 00H LJMP DKN KN1: CJNE A, # 02H, KN2 CLR TR0 LJMP DKN KN2: CJNE A, # 03H, DKN Mov sec, # 00H Mov A, Sec Mov b, # 10 Div AB Mov dptr, # TABLE MOVC A, @ a + dptr MOV P0, A Mov A, B Mov dptr, # TABLE MOVC A, @ a + dptr MOV P2, A Mov keycnt, # 00H DKN: JNB SP1, $ LJMP WT DELY10MS: Mov r6, # 20 D1: MOV R7, # 248 DJNZ R7, $ Djnz R6, D1 RET INT_T0: Inc TCNTA Mov A, TCNTA CJNE A, # 100, Next Mov tcnta, # 00H INC TCNTB Mov A, TCNTB CJNE A, # 4, Next Mov tcntb, # 00H Inc SEC Mov A, Sec CJNE A, # 100, DONE Mov sec, # 00H DONE: MOV A, SEC Mov b, # 10 Div AB Mov dptr, # TABLE MOVC A, @ a + dptr MOV P0, A Mov A, B Mov dptr, # TABLE MOVC A, @ a + dptr MOV P2, A Next: Reti Table: DB 3FH, 06H, 5BH, 4FH, 66H, 6DH, 7DH, 07H, 7FH, 6FH End 6. C language source program #include Unsigned char code dispcode [] = {0x3f, 0x06, 0x5b, 0x4f, 0x66, 0x6d, 0x7d, 0x07, 0x7f, 0x6f, 0x77, 0x7c, 0x39, 0x5e, 0x79, 0x71, 0x00}; Unsigned char second; UNSIGNED CHAR Keycnt; Unsigned int TCNT; Void main (void) { Unsigned char i, j; TMOD = 0x02; ET0 = 1; EA = 1; SECOND = 0; P0 = dispcode [second / 10]; P2 = dispcode [second% 10]; While (1) { IF (p3_5 == 0) { For (i = 20; I>0; I -) For (J = 248; J>0; J -); IF (p3_5 == 0) { Keycnt ++; Switch (Keycnt) { Case 1: TH0 = 0x06; TL0 = 0x06; Tr0 = 1; Break; Case 2: Tr0 = 0; Break; Case 3: Keycnt = 0; SECOND = 0; P0 = dispcode [second / 10]; P2 = dispcode [second% 10]; Break; } While (p3_5 == 0); } } } } Void T0 (Void) Interrupt 1 Using 0 { TCNT ++; IF (TCNT == 400) { TCNT = 0; SECOND ++; IF (Second == 100) { SECOND = 0; } P0 = dispcode [second / 10]; P2 = dispcode [second% 10]; } }, Read the full text