1-तार बस पर बात करना दर्दनाक हो सकता है। चाहे आप 1 सेंसर या 100 से बात कर रहे हों, आपको समय के बारे में सोचना होगा। मैंने कुछ साल पहले DS18B20 के लिए कुछ कोड लिखा था, लेकिन यह असेंबली में है। अगर यह किसी काम का है, तो यहां है:
;***************************************************************
;Title: Temperature Logger
;Description: Polls temperature every two seconds and returns a value
; in degC as well as the slope (rising, falling, steady)
;***************************************************************
Screen EQU $F684
;System Equates
PortA EQU $0000
DDRA EQU $0002
;Program Equates
TxPin EQU %00000001
RxPin EQU %00000010
IntPin EQU %10000000
;Commands
SkipROM EQU $CC
Convert EQU $44
ReadPad EQU $BE
;Constants
ASCII_0 EQU 48
Poll_D EQU 2000
;Macros
TxOn macro ; Send the 1-wire line Low
MOVB #TxPin,DDRA
MOVB #$00,PortA
endm
TxOff macro ;Releases the 1-wire line letting it return to High.
MOVB #$00,DDRA
endm
;-------------------------------------
;Main
;-------------------------------------
ORG $0D00
; Clear registers and initialise ports
Start: MOVB #$00, DDRA
Main: LDD #$00
JSR Init
LDAA #SkipROM
JSR Write
LDAA #Convert
JSR Write
JSR Wait
JSR Init
LDAA #SkipROM
JSR Write
LDAA #ReadPad
JSR Write
JSR Read ; read first 8 bits
TFR A, B
JSR Read ; read second 8 bits
; Convert bytes to BCD
LSRB
LSRB
LSRB
LSRB
STD TempNew
PSHA
PSHB
LDAB #6
MUL
TBA
PULB
ABA
CLRB
Conv_Lp:SUBA #10
BMI Conv_Dn
INCB
BRA Conv_Lp
Conv_Dn:ADDA #10
TFR A, Y
PULA
ABA
TFR Y, B
; convert BCD bytes to ASCII and store in temp register
LDX #Temp
ADDA #ASCII_0
STAA 0, X
INX
ADDB #ASCII_0
STAB 0, X
LDX #OutUp ; print 'The current temp is '
JSR Echo
LDX #Temp ; print ASCII bytes
JSR Echo
; compare stored temp with previously stored and print 'rising', 'falling' or 'steady'
LDD TempNew
SUBD TempOld
BGT Rising
BEQ Same
LDX #Fall
BRA EchDir
Rising: LDX #Rise
BRA EchDir
Same: LDX #Steady
EchDir: JSR Echo
; wait 2 seconds
LDX #Poll_D
Bla_Lp: JSR Del1ms
DBNE X, Bla_Lp
; set new temp as old temp and loop
LDD TempNew
STD TempOld
JMP Main
SWI
;-------------------------------------
;Subroutines
;-------------------------------------
Init: TxOn ; turn pin on
uDelay 500 ; for 480us
TxOff ; turn pin off
uDelay 70 ; wait 100us before reading presence pulse
JSR Wait
RTS
Wait: LDX #120
Wait_Lp:JSR Del1ms
DBNE X, Wait_Lp
RTS
Write: PSHX
PSHA
LDX #8 ; 8 bits in a byte
Wr_Loop:BITA #%00000001
BNE Wr_S1 ; bit is set, send a 1
BEQ Wr_S0 ; bit is clear, send a 0
Wr_Cont:LSRA ; shift input byte
uDelay 100
DBNE X, Wr_Loop ; shifted < 8 times? loop else end
BRA Wr_End
Wr_S1: TxOn ; on for 6, off for 64
uDelay 6
TxOff
uDelay 64
BRA Wr_Cont
Wr_S0: TxOn ; on for 60, off for 10
uDelay 60
TxOff
uDelay 10
BRA Wr_Cont
Wr_End: PULA
PULX
RTS
Read: PSHB
LDAB #%00000001
CLRA
Rd_Loop:TxOn ; on for 6, off for 10
uDelay 6
TxOff
uDelay 10
BRSET PortA, #RxPin, Rd_Sub1 ; high? add current bit to output byte
Rd_Cont:uDelay 155 ; delay and shift.. 0? shifted 8 times, end
LSLB
BNE Rd_Loop
BRA Rd_End
Rd_Sub1:ABA
BRA Rd_Cont
Rd_End: PULB
RTS
uDelay macro ;Delay a mutliple of 1us (works exactly for elays > 1us)
PSHD
LDD #\1
SUBD #1
LSLD
\@LOOP NOP
DBNE D, \@LOOP
PULD
endm
;-------------------------------------
;General Functions
;-------------------------------------
; delays
Del1us: RTS
Del1ms: PSHA
LDAA #252
Del_ms: JSR Del1us
JSR Del1us
JSR Del1us
CMPA $0000
CMPA $0000
NOP
DECA
BNE Del_ms
CMPA $0000
NOP
PULA
RTS
; display text from address of X to \0
Echo: PSHY
PSHB
LDAB 0, X
Ech_Lp: LDY Screen
JSR 0, Y
INX
LDAB 0, X
CMPB #0
BNE Ech_Lp
PULB
PULY
RTS
Interrupt:
SWI
RTI
;-------------------------------------
;Variables
;-------------------------------------
ORG $0800
OutUp: DC.B 'The current temperature is ', 0
Rise: DC.B ' and Rising', $0D, $0A, 0
Steady: DC.B ' and Steady', $0D, $0A, 0
Fall: DC.B ' and Falling', $0D, $0A, 0
Temp: DS 2
DC.B 0
TempOld:DS 2
TempNew:DS 2