I am new in microcontroller. I want to use 8051 to monitor the heart rate. After going through some tutorials and online materials i wrote the following code but could not identify the errors in the code.

ORG 000H                    // origin

MOV DPTR,#LUT             // moves starting address of LUT to DPTR

MOV P1,#00000000B             // sets P1 as output port

MOV P0,#00000000B           // sets P0 as output port

MAIN: MOV R6,#230D            // loads register R6 with 230D

SETB P3.5                         // sets P3.5 as input port

MOV TMOD,#01100001B           // Sets Timer1 as Mode2 counter &Timer0 as Mode1 timer

MOV TL1,#00000000B                  // loads TL1 with initial value

MOV TH1,#00000000B                     // loads TH1 with initial value

SETB TR1                                      // starts timer(counter) 1

BACK: MOV TH0,#00000000B              // loads initial value to TH0

MOV TL0,#00000000B                       // loads initial value to TL0

SETB TR0                                                  // starts timer 0

HERE: JNB TF0,HERE                       // checks for Timer 0 roll over

CLR TR0                                              // stops Timer0

CLR TF0                                                // clears Timer Flag 0

DJNZ R6,BACK

CLR TR1                                                   // stops Timer(counter)1

CLR TF0                                                        // clears Timer Flag 0

CLR TF1                                                           // clears Timer Flag 1

ACALL DLOOP              // Calls subroutine DLOOP for displaying the count

SJMP MAIN                       // jumps back to the main loop

DLOOP: MOV R5,#252D

BACK1: MOV A,TL1              // loads the current count to the accumulator

MOV B,#4D                                // loads register B with 4D

MUL AB                                   // Multiplies the TL1 count with 4

MOV B,#100D                       // loads register B with 100D

DIV AB                                   // isolates first digit of the count

SETB P1.0                              // display driver transistor Q1 ON

ACALL DISPLAY                          // converts 1st digit to 7seg pattern

MOV P0,A                                  // puts the pattern to port 0

ACALL DELAY

ACALL DELAY

MOV A,B

MOV B,#10D

DIV AB                                   // isolates the second digit of the count

CLR P1.0                                // display driver transistor Q1 OFF

SETB P1.1                              // display driver transistor Q2 ON

ACALL DISPLAY                      // converts the 2nd digit to 7seg pattern

MOV P0,A

ACALL DELAY

ACALL DELAY

MOV A,B                   // moves the last digit of the count to accumulator

CLR P1.1                    // display driver transistor Q2 OFF

SETB P1.2                   // display driver transistor Q3 ON

ACALL DISPLAY                  // converts 3rd digit to 7seg pattern

MOV P0,A                        // puts the pattern to port 0

ACALL DELAY                      // calls 1ms delay

ACALL DELAY

CLR P1.2

DJNZ R5,BACK1                  // repeats the subroutine DLOOP 100 times

MOV P0,#11111111B

RET

DELAY: MOV R7,#250D                   // 1ms delay

DEL1: DJNZ R7,DEL1

RET

DISPLAY: MOVC A,@A+DPTR     // gets 7seg digit drive pattern for current 

value in A

CPL A

RET

LUT: DB 3FH                                 // LUT starts here

DB 06H

DB 5BH

DB 4FH

DB 66H

DB 6DH

DB 7DH

DB 07H

DB 7FH

DB 6FH

END

Can someone help me sort out the problem or give and alternative code please?
The circuit diagram is as seen on the attachment bellow

 

Your code seems to work fine. I gave it a 3 Hz pulse at P3.5 and it displayed 180 after 60 seconds.

What is your complaint about the project? Hardware or software?

Allen

 

Thank you for your reply. I don't understand how you represented S1 reset from your simulation diagram. Could you please tell me how to represent S1 reset button?

 

C4 and R1 forms what we called power-up reset circuit. On power-up C4 is like a short-circuit which would bring logic high to the RST pin. When C4 is slowly charged up by R1, RST would drop to logic low.

You can put a switch across C4 if you need a manual reset. It's also a good idea to put a diode across C4 to make sure that it is fully discharged during powered down.

Allen

 

I tried to build the hex file in M-IDE studio for MCS-51 but the program keeps loading forever. What might be the problem? There is no error in the program.