DS18B20 reads temperature and displays it - assembly program

*
Program effect: Read the temperature value through DS18B20 and display the corresponding temperature value
The program focuses on understanding the timing and delay time
*/

DS18DQ EQU P1.3 //P1.3 is equivalent to DS18DQ, which is easy to understand
SPEAKER EQU P2.0 //Drive the buzzer
TEMPH EQU 29H //Save the low 8 bits of the temperature read
TEMPL EQU 28H //Save the high 8 bits of the temperature read
DS18FLAG EQU 40H //Set the flag
ORG 0000H
LJMP START
ORG 0030H
START: MOV 30H,#00 //Set the initial value
MOV 31H,#00
MOV 32H,#00
START1: LCALL DS18_GF //Set the working mode of DS18B20
LCALL CONVERT_TEMPERATURE //Output conversion temperature command
LCALL DELAY750MS //Delay 750ms
LCALL GET_TEMPERATURE //Get temperature data
LCALL CAL_TEMPERATURE //Calculate temperature value
LCALL DISPLAY //Call the display to prevent the display from dropping
LJMP START1 //Infinite loop
//Initialize the subroutine
DS18_START:
PUSH 07H //Save the value of R7 to prevent changing the value of R7
SETB DS18DQ //Pull the data line high
NOP //Delay 1us
CLR DS18DQ //Pull the data line low
MOV R7,#0 //Delay about 512us
DJNZ R7,$
SETB DS18DQ //Pull the data line high
MOV R7,#40
DS18_START1: //Delay about 160us
JNB DS18DQ,DS18_START2 //Check if DS18B20 is working properly
DJNZ R7,DS18_START1
SETB DS18FLAG //Abnormal work
CLR SPEAKER //Drive the buzzer and alarm
DS18_START2:
CLR DS18FLAG
MOV R7,#100 //Delay month 200us
DJNZ R7,$
POP 07H //Restore the value of R7
RET
//Set DS18B20 working mode
DS18_GF:CLR DS18FLAG //Clear flag
LCALL DS18_START //Call initialization subroutine
MOV A,#0CCH //Jump ROM instruction
LCALL DS18_SEND //
MOV A,#4EH //Write data to RAM
LCALL DS18_SEND
MOV A,#75
LCALL DS18_SEND
MOV A,#0
LCALL DS18_SEND
MOV A,#7FH //Set working mode
LCALL DS18_SEND
CLR DS18DQ //Release bus
LCALL DELAY500US //Delay 500us
LOOP: LCALL CONVERT_TEMPERATURE //Call rotor program
MOV R5,#80
LOOP1: LCALL DISPLAY //Call display to prevent display dropout and wait for conversion to complete
DJNZ R5,LOOP1
LCALL GET_TEMPERATURE //Get conversion value
LCALL CAL_TEMPERATURE //Calculate temperature value
LJMP LOOP
RET[page]
//Output conversion temperature command
CONVERT_TEMPERATURE:
LCALL DS18_START //Call initialization subroutine
MOV A,#0CCH //Jump ROM instruction
LCALL DS18_SEND
MOV A,#44H //Temperature conversion
LCALL DS18_SEND
RET
//Read temperature data
GET_TEMPERATURE:
LCALL DS18_START //Call initialization subroutine
MOV A,#0CCH //Jump ROM instruction
LCALL DS18_SEND
MOV A,#0BEH //Data from RAM
LCALL DS18_SEND
LCALL DELAY60US
LCALL DS18_READ
MOV TEMPL,A //Store the lower eight bits of the obtained data in TEMPL
LCALL DS18_READ
MOV TEMPH,A //Store the upper eight bits of the obtained data in TEMPH
CLR DS18DQ //Reset. Otherwise, it will keep reading until
LCALL DELAY501US //Store the ninth byte temporarily
RET
//Calculate the temperature value for easy display
CAL_TEMPERATURE:
PUSH 07H //Store temporarily to prevent changing the data in R7
CLR C //Clear the carry flag
MOV R7,#04H //Number of cycles

EX2: MOV A,TEMPH // The functions of these statements are:
RRC A // The integer bit is in: TEMPL
MOV TEMPH,A // The integer bit is in: the high half of TEMPH
MOV A,TEMPL
RRC A
MOV TEMPL,A
DJNZ R7,EX2 //

MOV A,TEMPH //
RLC A //The functions of these statements are:
RLC A //Move the high half of TEMPH to the low four bits
RLC A
RLC A //
ANL A,#0FH //Shield the high four bits and keep the low four bits
MOV DPTR,#TAB_TEMP //Assign the first address of the value table with a decimal point
MOVC A,@A+DPTR
MOV 30H,A //Store the value temporarily for display
MOV A,TEMPL
CLR C
MOV B,#0AH
DIV AB //Separate the high and low four bits of the integer
MOV 32H,A //Store the tens digit temporarily
MOV A,B
ADD A,#10H
MOV 31H,A //Store the ones digit temporarily
POP 07H //Restore the value of R7
RET
//Write data subroutine
DS18_SEND:
PUSH 06H //Protect the value of Rn
PUSH 07H
//The following statements are "write pen and mouse"
SETB DS18DQ //The write timing is determined by the falling edge of DS18DQ
NOP //Delay 1us
MOV R6,#08H //Number of loops, one byte
DS18_SEND1:
CLR DS18DQ //Pull low to generate a falling edge
MOV R7,#07 //Delay about 15us
DJNZ R7,$
RRC A //Move the high bit of the data to be written to C
MOV DS18DQ,C //Then assign the value of C to DS18DQ
MOV R7,#30 //Delay time is about 60us, only about 45us is needed
DJNZ R7,$
SETB DS18DQ //Pull high to prepare, the next falling edge will be generated
DJNZ R6,DS18_SEND1 //Judge whether the number of loops is enough
POP 07H //Restore the data of Rn
POP 06H
RET
The full program is too long, please download it from here: http://www.51hei.com/ziliao/file/ds182051hei.asm

This program has been tested successfully.