AT89S51 microcontroller 00-59 seconds timer design

1. As shown in the figure below, the P0 and P2 ports of the AT89S51 single chip microcomputer include two common-causal digital tubes, and the P0-port drives the ten digits of the second time, while the P2 port is driven to display the second time. 2. Circuit Schematic Figure 4.11.1 3. System board hardware connection (1. Connect the P0.0 / AD0-P0.7 / AD7 port in the "MCU system" area to any of the AH ports in the "four-way static digital display module" area; requirements: P0 .0 / AD0 corresponds to B, ..., P0.7 / AD7 corresponding to H, P0.1 / AD1. (2. Connect the P2.0 / A8-P2.7 / A15 port in the "MCU system" area to any of the AH ports in the "four-way static digital display module" area; requirements: P2 .0 / A8 corresponds to a, p2.1 / a9 corresponding to B, ..., P2.7 / A15 corresponding to H. 4. Program design content (1. In the design process, we use a storage unit as a second count unit. When a second, let the second count unit add 1, when the second count reaches 60, automatically returns to 0, from the new second count. (2. For data in the second counting unit, it is to separate its ten digits and numbers, and the method still uses the pair of 10 removal and 10 surplus. (3. Display on digital code is still completed by checking the table. (4. Generation of one second here we use software exact delayed methods to complete, after exactly calculation for 1 second for 1.002 seconds. DELY1S: MOV R5, # 100 D2: MOV R6, # 20 D1: MOV R7, # 248 DJNZ R7, $ Djnz R6, D1 DJNZ R5, D2 RET 5. Program block diagram Figure 4.11.2 6. Compilation Source Procedure SECOND EQU 30H ORG 0 START: MOV Second, # 00H Next: MOV A, SECOND Mov b, # 10 Div AB Mov dptr, # TABLE MOVC A, @ a + dptr MOV P0, A Mov A, B MOVC A, @ a + dptr MOV P2, A LCALL DELY1S Inc Second Mov A, SECOND CJNE A, # 60, Next LJMP START DELY1S: MOV R5, # 100 D2: MOV R6, # 20 D1: MOV R7, # 248 DJNZ R7, $ Djnz R6, D1 DJNZ R5, D2 RET Table: DB 3FH, 06H, 5BH, 4FH, 66H, 6DH, 7DH, 07H, 7FH, 6FH End 7. C language source program #include Unsigned char code Table [] = {0x3f, 0x06, 0x5b, 0x4f, 0x66, 0x6d, 0x7d, 0x07, 0x7f, 0x6f}; Unsigned char second; Void delay1s (void) { Unsigned Char i, J, K; For (k = 100; k "0; k -) For (i = 20; i "0; I -) For (j = 248; j "0; j -); } Void main (void) { SECOND = 0; P0 = Table [Second / 10]; P2 = Table [second% 10]; While (1) { Delay1s (); SECOND ++; IF (Second == 60) { SECOND = 0; } P0 = Table [Second / 10]; P2 = Table [second% 10]; } }, Read the full text

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