Assembly program for connecting DS18b20 and 51 microcontroller

This assembly program is only suitable for the connection between a single DS18B20 and a 51 microcontroller, and the crystal oscillator is about 12MHZ
DQ: DS18B20 data bus pin
FLAG1: flag bit, when "1" means that DS18B20 is detected
TEMPER_NUM: save the read temperature data
TEMPER_LEQU36H
TEMPER_HEQU35H

DQBITP1.7

; DS18B20 initialization assembly program
; //********************************************//
INIT_1820:
SETBDQ
NOP
CLRDQ
MOVR0,#06BH
TSR1:
DJNZR0,TSR1; Delay
SETBDQ
MOVR0,#25H
TSR2:
JNBDQ,TSR3
DJNZR0,TSR2
LJMPTSR4; Delay
TSR3:
SETBFLAG1; Set the flag to indicate that DS1820 exists
LJMPTSR5
TSR4:
CLRFLAG1; Clear the flag to indicate that DS1820 does not exist
LJMPTSR7
TSR5:
MOVR0,#06BH
TSR6:
DJNZR0,TSR6; Delay
TSR7:
SETBDQ
RET
;//*********************************************//

; Rewrite the setting value of DS18B20 temporary memory
; //********************************************//
RE_CONFIG:
JBFLAG1,RE_CONFIG1; If DS18B20 exists, go to RE_CONFIG1
RET
RE_CONFIG1:
MOVA,#0CCH; Send SKIP ROM command
LCALLWRITE_1820
MOVA,#4EH; Send write temporary memory command
LCALLWRITE_1820
MOVA,#00H; Write 00H to TH (alarm upper limit)
LCALLWRITE_1820
MOVA,#00H; Write 00H to TL (alarm lower limit)
LCALLWRITE_1820
MOVA,#1FH; Select 9-bit temperature resolution
LCALLWRITE_1820
RET
;//********************************************//

; Read the converted temperature value
; //********************************************//
GET_TEMPER:
SETBDQ; Timing entry

LCALLINIT_1820
JBFLAG1,TSS2
RET; If DS18B20 does not exist, return to
TSS2:
MOVA,#0CCH; Skip ROM matching
LCALLWRITE_1820
MOVA,#44H; Issue temperature conversion command
LCALLWRITE_1820

LCALLINIT_1820
MOVA,#0CCH; Skip ROM matching
LCALLWRITE_1820
MOVA,#0BEH; Issue a temperature read command
LCALLWRITE_1820
LCALLREAD_1820
MOVTEMPER_NUM,A; Save the read temperature data
RET
;//************************************************//

; Read DS18B20 program, read one byte of data from DS18B20
; //********************************************//
READ_1820:
MOVR2,#8
RE1:
CLRC
SETBDQ
NOP
NOP
CLRDQ
NOP
NOP
NOP
SETBDQ
MOVR3,#7
DJNZR3,$
MOVC,DQ
MOVR3,#23
DJNZR3,$
RRCA
DJNZR2,RE1
RET
;//************************************************//

; Write the program for DS18B20
; //********************************************//
WRITE_1820:
MOVR2,#8
CLRC
WR1:
CLRDQ
MOVR3,#6
DJNZR3,$
RRCA
MOVDQ,C
MOVR3,#23
DJNZR3,$
SETBDQ
NOP
DJNZR2,WR1
SETBDQ
RET
; //************************************************//

; Read DS18B20 program, read two bytes of temperature data from DS18B20
; //********************************************//
READ_18200:
MOVR4,#2; Read the high and low bits of temperature from DS18B20
MOVR1,#36H; Store the low bit in 36H (TEMPER_L) and the high bit in 35H (TEMPER_H)
RE00:
MOVR2,#8
RE01:
CLRC
SETBDQ
NOP
NOP
CLRDQ
NOP
NOP
NOP
SETBDQ
MOVR3,#7
DJNZR3,$
MOVC,DQ
MOVR3,#23
DJNZR3,$
RRCA
DJNZR2,RE01
MOV@R1,A
DECR1
DJNZR4,RE00
RET
;//************************************************//

; Convert the temperature data read from DS18B20
; //********************************************//
TEMPER_COV:
MOVA,#0F0H
ANLA,TEMPER_L; Discard the four decimal places of the low temperature
SWAPA
MOVTEMPER_NUM,A
MOVA,TEMPER_L
JNBACC.3,TEMPER_COV1; Round off the temperature value
INCTEMPER_NUM

TEMPER_COV1:
MOVA,TEMPER_H
ANLA,#07H
SWAPA
ORLA,TEMPER_NUM
MOVTEMPER_NUM,A; Save the converted temperature data
LCALLBIN_BCD
RET
;//************************************************//

; Convert the hexadecimal temperature data into compressed BCD code
; //********************************************//
BIN_BCD:
MOVDPTR,#TEMP_TAB
MOVA,TEMPER_NUM
MOVCA,@A+DPTR
MOVTEMPER_NUM,A
RET[page]

TEMP_TAB:
DB00H,01H,02H,03H,04H,05H,06H,07H
DB08H,09H,10H,11H,12H,13H,14H,15H
DB16H,17H,18H,19H,20H,21H,22H,23H
DB24H,25H ,26H,27H,28H,29H,30H,31H
DB32H,33H,34H,35H,36H,37H,38H,39H
DB40H,41H,42H,43H,44H,45H,46H,47H
DB48H,49H,50H,51H, 52H,53H,54H,55H
DB56H,57H,58H,59H,60H,61H,62H,63H
DB64H,65H,66H,67H,68H,69H,70H
;//************************ ************************//

The following is a ds18b20 assembler program
; *************************************
 FLAG1 BIT F0 ;DS18B20 exists flag bit
 DQ BIT P1.7
 TEMPER_L EQU 29H
 TEMPER_H EQU 28H
 A_BIT EQU 35H
 B_BIT EQU 36H
 ;************ds18b20 assembler program starts********************
     ORG 0000H
     AJMP MAIN
     ORG 0100H
;**************Main program starts************
MAIN:
      LCALL INIT_18B20
      ;LCALL RE_CONFIG
      LCALL GET_TEMPER
     AJMP CHANGE

;**********DS18B20 reset procedure********************
INIT_18B20: SETB DQ
               NOP
               CLR DQ
               MOV R0,#0FBH
         TSR1: DJNZ R0,TSR1 ;Delay
               SETB DQ
               MOV R0,#25H
         TSR2: JNB DQ ,TSR3
               DJNZ R0,TSR2
         TSR3: SETB FLAG1 ;Set the flag, indicating that DS18B20 exists
               CLR P2.0 ;Diode indication
               AJMP TSR5
         TSR4: CLR FLAG1
               LJMP TSR7
          TSR5: MOV R0,#06BH
          TSR6: DJNZ R0,TSR6
          TSR7:SETB DQ ;Indicates that it does not exist
                RET
;********************Set DS18B20 register setting value**************
;RE_CONFIG:
           ;JB FLAG1,RE_CONFIG1
            ;RET
;RE_CONFIG1: MOV A,#0CCH ; Skip ROM command
            ; LCALL WRITE_18B20
            ;MOV A,#4EH
            ;LCALL WRITE_18B20 ; Write register command
            ; MOV A,#00H ; Write 00H in the upper limit of alarm
            ; LCALL WRITE_18B20
            ;MOV A,#00H ; Write 00H in the lower limit of alarm
           ; LCALL WRITE_18B20
           ;MOV A,#1FH ; Select nine-bit temperature resolution
           ; LCALL WRITE_18B20
           ; RET
;********************Read the converted temperature value****************
GET_TEMPER:
            SETB DQ
            LCALL INIT_18B20
            JB FLAG1,TSS2
            RET ; Return to TSS2 if it does not exist
      : MOV A,#0CCH ; Skip ROM
            LCALL WRITE_18B20
            MOV A,#44H ; Issue temperature conversion command
            LCALL WRITE_18B20

            LCALL DISPLAY ; Delay
            LCALL INIT_18B20
            MOV A,#0CCH ; Skip ROM
            LCALL WRITE_18B20
            MOV A,#0BEH ; Issue a temperature read command
            LCALL WRITE_18B20
            LCALL READ2_18B20 ; Read two bytes of temperature
            RET
 ; ****************** Write ds18b20 assembly program **********
 WRITE_18B20:
            MOV R2,#8
            CLR C
        WR1:
              CLR DQ

              MOV R3,#6
              DJNZ R3,$
              RRC A
              MOV DQ,C
              MOV R3,#23
              DJNZ R3,$
              SETB DQ
              NOP
              DJNZ R2,WR1
              SETB DQ
              RET

 ;***********Read 18B20 program, read two bytes of temperature*********
 READ2_18B20:
            MOV R4,#2 ;The low bit is 29H, the high bit is 28H

            MOV R1,#29H
      RE00: MOV R2,#8
      RE01: CLR C
            SETB C
            NOP
            NOP

            CLR DQ
            NOP
            NOP
            NOP
            SETB DQ
            MOV R3,#7
            DJNZ R3,$
            MOV C,DQ
            MOV R3,#23
             DJNZ R3,$
            RRC A
            DJNZ R2,RE01
            MOV @R1,A
            DEC R1
            DJNZ R4,RE00
            RET
 ;************Read the temperature and convert it into data**************

CHANGE: MOV A,29H
            MOV C,28H.0 ; Move the lowest bit in 28H into C
            RRC A
            MOV C,28H.1
            RRC A
            MOV C,28H.2
            RRC A
            MOV C,28H.3
            RRC A
            MOV 29H,A
            ; setb p2.0
            LCALL DISPLAY ; Call the digital tube display subroutine

           ; setb P2.0
            LJMP MAIN
 ;*******************DISPLAY******
 DISPLAY: mov a,29H;Convert the hexadecimal number in 29H to decimal
             mov b,#10 ;Decimal/10=decimal
             div ab
             mov b_bit,a ;Tens digit is in a
             mov a_bit,b ;Ones digit is in b
             mov dptr,#TAB ;Specify the start address of table lookup
             mov r0,#4
             dpl1: mov r1,#250 ;Display 1000 times
             dplop: mov a,a_bit ;Get the ones digit
             MOVC A,@A+DPTR ;Check the 7-segment code of the ones digit
             mov p0,a ;Send the 7-segment code of the ones digit
             clr p2.5;Open the ones digit to display
             acall d1ms ;Display 1ms
             setb p2.5
             mov a,b_bit ;Get the tens digit
             MOVC A,@A+DPTR ; Check the 7-segment code of the ten-digit
             mov p0,a ; Send the 7-segment code of the ten-digit
             clr p2.4 ; Open the ten-digit display
             acall d1ms ; Display 1ms
             setb p2.4
             djnz r1,dplop ; 100 times endless loop
             djnz r0,dpl1 ; 4 100 times endless loop
             ret

 ;***********************************
             D1MS: MOV R7,#80 ;1MS delay (calculated as 12MHZ)
             DJNZ R7,$
             RET
 ;*****************************
 TAB: DB 0C0H,0F9H,0A4H,0B0H,99H,92H,82H,0F8H,80H,90H