基于16F877A和DS18B20的测温程序

以下是一个0到99度的测温程序，只要把数据处理程序改一下就可以改变测量范围和精度。

#INCLUDE 16F877A.INC>

CBLOCK 20H

INPUT_HIGH_8 ;high 8 bit,don't allow other P use it but temperature conversion p

INPUT_LOW_8 ;low 8 bit,don't allow other P use it but temperature conversion p

DELAY_TEMP0

DELAY_TEMP1

PASS_TEMP

UNITS_ORDER

TENS_DIGIT

COUNT_16

ENDC

ORG 00H

NOP

GOTO INITIAL

ORG 05H

TABLE

ADDWF PCL,1

DT 0C0H,0F9H,0A4H,0B0H,99H,92H,82H,0F8H,80H,90H,90H,90H,90H ;comment anode

DISPLAY

MOVFW UNITS_ORDER

CALL TABLE

MOVWF PORTC

BCF PORTA,0 ;trigger transistor of NPN than display units_order

CALL DELAY_1MS

BSF PORTA,0 ;close

MOVFW TENS_DIGIT

CALL TABLE

MOVWF PORTC

BCF PORTA,1 ;trigger transistor of NPN than display tens_digit

CALL DELAY_1MS

BSF PORTA,1

RETURN

DELAY_1MS

MOVLW 12H

MOVWF DELAY_TEMP0

MOVLW 12H

MOVWF DELAY_TEMP1

DECFSZ DELAY_TEMP1

GOTO $-1

DECFSZ DELAY_TEMP0

GOTO $-5

RETURN

INITIAL

BANKSEL TRISA

MOVLW 00H

MOVWF TRISA ;porta0..1 to launch LED, porta2 18b20 communICation port

MOVLW B'00000110' ;set porta as digital port

MOVWF ADCON1

MOVLW 00H

MOVWF TRISC ;8 bits led data bus

MOVLW 0FFH ;portb1 as a command key

MOVWF TRISB

MOVLW 00H

MOVWF OPTION_REG ;portb as week pull up

BANKSEL PORTA

CLRF UNITS_ORDER

CLRF TENS_DIGIT

MAIN

CALL DISPLAY ;press key to start the function

BTFSC PORTB,2

GOTO $-2

BTFSS PORTB,2 ;key release?

GOTO $-1

CALL INITIAL_18B20

BTFSS DELAY_TEMP1,1

GOTO MAIN

MOVLW 0CCH ;skip the rom

MOVWF PASS_TEMP

CALL WRITE_18B20

MOVLW 44H ;release the command of conversion

MOVWF PASS_TEMP

CALL WRITE_18B20

MOVLW D'30'

MOVWF COUNT_16

MOVLW D'90' ;delay 900ms for conversion

MOVWF DELAY_TEMP1

MOVLW D'110'

MOVWF DELAY_TEMP0

DECFSZ DELAY_TEMP0

GOTO $-1

DECFSZ DELAY_TEMP1

GOTO $-5

DECFSZ COUNT_16

GOTO $-9

CALL INITIAL_18B20

BTFSS DELAY_TEMP1,1

GOTO MAIN

MOVLW 0CCH

MOVWF PASS_TEMP

CALL WRITE_18B20 ;release the command of reading

MOVLW 0BEH

MOVWF PASS_TEMP

CALL WRITE_18B20

CALL READ_18B20

CALL INITIAL_18B20 ;end the other data to transmit

BTFSS DELAY_TEMP1,1

GOTO MAIN

CALL BCD_CONVERSION

GOTO MAIN

INITIAL_18B20

BCF PORTB,2

BANKSEL TRISA

BCF TRISA,2

BANKSEL PORTA

MOVLW 0BH

MOVWF DELAY_TEMP0

MOVLW 22H

MOVWF COUNT_16

DECFSZ COUNT_16,1

GOTO $-1 ;delay 586us

DECFSZ DELAY_TEMP0,1

GOTO $-5

BANKSEL TRISA

BSF TRISA,2 ;release the bus

BANKSEL PORTA

MOVFW PORTA

MOVLW D'25' ;delay 76us

MOVWF DELAY_TEMP0

DECFSZ DELAY_TEMP0,1

GOTO $-1

BTFSS PORTA,2

GOTO $+3

BCF DELAY_TEMP1,1 ;not respondence

GOTO $+2

BSF DELAY_TEMP1,1

MOVLW D'160' ;delay 480us

MOVWF DELAY_TEMP0

DECFSZ DELAY_TEMP0,1

GOTO $-1

BSF DELAY_TEMP1,1 ;the slave device responded and set the bit of flag

RETURN

WRITE_18B20

MOVLW 08H

MOVWF DELAY_TEMP0

BCF STATUS,C

WR_LOOP1

BCF PORTA,2

BANKSEL TRISA

BCF TRISA,2

BANKSEL PORTA

NOP

NOP

RRF PASS_TEMP,1

BTFSS STATUS,C

GOTO WR_ZERO

BANKSEL TRISA

BSF TRISA,2

BANKSEL PORTA

WR_ZERO

MOVLW D'25' ;delay 75us

MOVWF DELAY_TEMP1

DECFSZ DELAY_TEMP1

GOTO $-1

BANKSEL TRISA

BSF TRISA,2

BANKSEL PORTA

NOP

NOP

DECFSZ DELAY_TEMP0,1

GOTO WR_LOOP1

RETURN

READ_18B20

MOVLW D'16'

MOVWF DELAY_TEMP0

READ_LOOP2

BCF PORTA,2

BANKSEL TRISA

BCF TRISA,2

BANKSEL PORTA

NOP

NOP

NOP

NOP

NOP

BANKSEL TRISA

BSF TRISA,2

BANKSEL PORTA

NOP

NOP

NOP

NOP

BTFSS PORTA,2

GOTO $+3

BSF STATUS,C

GOTO $+2

BCF STATUS,C

RRF INPUT_HIGH_8,1

RRF INPUT_LOW_8,1

MOVLW D'20' ;delay 60us

MOVWF DELAY_TEMP1

DECFSZ DELAY_TEMP1,1

GOTO $-1

DECFSZ DELAY_TEMP0,1

GOTO READ_LOOP2

RETURN

BCD_CONVERSION

MOVLW 08H

MOVWF COUNT_16

MOVLW 0FH

ANDWF INPUT_HIGH_8,1

SWAPF INPUT_HIGH_8,1

MOVLW 0F0H

ANDWF INPUT_LOW_8,1

SWAPF INPUT_LOW_8,1

MOVFW INPUT_LOW_8

ADDWF INPUT_HIGH_8,1 ;save 8bits data in input_high_8

CLRF INPUT_LOW_8

BCF STATUS,C

LOOP_8TIMES

RLF INPUT_HIGH_8,1

RLF INPUT_LOW_8,1

DECFSZ COUNT_16

GOTO $+2

GOTO SEPARATE_2RS

MOVLW INPUT_LOW_8

MOVWF FSR

CALL ADJ_BCD

GOTO LOOP_8TIMES

ADJ_BCD

MOVLW 03H

ADDWF INDF,W

MOVWF TENS_DIGIT

BTFSC TENS_DIGIT,3

MOVWF INDF ;if the low four bits plus 3 is more than 7,

MOVLW 30H ;add 3,if less than 7,do not change it

ADDWF INDF,W ;if the high four bits plus 3 is more than 7,than

MOVWF TENS_DIGIT

BTFSC TENS_DIGIT,7 ;add 3,if less than 7,do not change it

MOVWF INDF

RETURN

SEPARATE_2RS

MOVFW INPUT_LOW_8

MOVWF UNITS_ORDER

MOVWF TENS_DIGIT

MOVLW 0FH

ANDWF UNITS_ORDER,1

MOVLW 0F0H

ANDWF TENS_DIGIT,1

SWAPF TENS_DIGIT,1

RETURN

END