Example of using PIC to read and write 1-wire EEPROM DS2430

Example program for reading and writing 1-wire EEPROM DS2430 using P IC

;--------------------------------------------------------------------
;
; 1-wire device aCCess
;DS2430
;memory function
;write scratchpad
;read scratchpad
;
;read memory : 
; resource occupy by ICD2
; PROM 0x1f00 - 0x1fff
; RAM  0x70,0xf0,0x170,0x1e5~0x1f0
;--------------------------------------------------------------------
;  master      action
;  0xf0 + start addr(8)  =>  scratchpad(8) -->  master
;  none          =>  scratchpad(9) -->  master
;  none            => scartchpad(a) -->  master
;  
;  none            => scratchpad(0x1f)-->  master[wrap around]
;  reset pulse          =>    stop sending data
;
;  0xf0+reset pulse      =>  EEPROM(0x00-0x1F) --> scratchpad(0x00-0x1F)

; copy scratchpad 
;  master
;  0x55 + 0xa5  =>  scratchpad(000-0x1f) --> EEPROM(0x00-0x1F)
;  hELD hi for 10ms 
;    0xf0 + reset pulse => copy whole from EEPROM to SCRATCHPAD
;        use timer as a delay timer
;
;  author : Rex Chen
;  date : May,8th
;  ver  : 1.81
;

  list p=16F877A
＃i nclude p16f877a.inc
 __CONFIG _CPD_OFF & _CP_ALL & _DEBUG_ON & _BODEN_OFF & _LVP_OFF & _PWRTE_OFF & _WDT_OFF & _XT_OSC
 
 

#define OneWireDHi bsf PORTC,Bit2
#define OneWireDLo bcf PORTC,Bit2
   

#define CARRY  STATUS,C
#define ZERO  STATUS,Z

Bit0  equ H'0000'
Bit1  equ H'0001'
Bit2  equ H'0002'
Bit3  equ H'0003'
Bit4  equ H'0004'
Bit5  equ H'0005'
Bit6  equ H'0006'
Bit7  equ H'0007'
;variable defination
 cbLOCk  0x20  ; RAM area 0x20- 0x7f
 SYSFLAG
 TxB      ; Command buffer been send
 TxBuffer    ; data buffer been send
 RxB      ; Command buffer been received
 TempB    ; Temp Byte to roll the data
 LoopCounter
 Addr    ; address to access BQ2430A
 PBDir    ; port C direction log file 
 PADir    ; port A direction log file
 Temp
 ErrCode    ;
 W_SAVE
 STATUS_SAVE
 TxBuf:8    ; Tx Temp buffer
 Offset
 endc    
 
;;
 cblock 0xa0
 SARS1
 SARS2
 SARS3
 endc 
 
 cblock 0x100
 HateSARS1
 HateSARS2
 HateSARS3
 HateSARS4
 endc
 
 cblock 0x190
 SARSISAPig0
 SARSIsAPig1
 SARSIsAPig2
 SARSIsAPig3
 SARSIsAPig4
 SARSIsAPig5
 endc 
 
 
;---------------- SYSFLAG ----------------------------------
fTxHi  equ  H'0000'
fTxLo  equ  H'0001'
fRxMode  equ  H'0002'
;;
;;
;; there are 4 memory block
;; 1. EEPROM & 2. memory scratchpad
;; 3. application register
;; 4.register scratchpad
;; aliase
;;
;; memory function
;; write memory scratch
;; read memory scratch
;; copy memory scratch to EEPROM
;; read EEPROM to memory scratch 
;;

WScratch equ  H'0F'  ; 0x0f + Addr + data + data + .+ reset pulse
        ; // [Master --> ScratchPad ]
RScratch equ  H'AA'  ; 0xaa + Addr + R + R +.. + reset pulse
        ; // [ScratchPad --> Master ]
CPScratch equ  H'55'  ; 0x55 + 0xa5 + hi 10ms  // [ScratchPad --> EEPROM ]
REEROM  equ  H'F0'  ; 0xf0 + Addr +R +R + reset pulse
        ; // [EEPROM(addr) --> ScratchPad]
        ; 0xf0 + reset pulse  // [EEPROM --> ScratchPad]

;; application register , application register is OTP, there are 7 bytes
;; pay attention when you use application register , it's a 64 bit OTP
WApR  equ  H'99'  ; 0x99 + Addr + data + data .. + reset pulse 
        ; [Master  --> Application Reg]
RStatus  equ  H'66'  ; 0x66 + 0x00 + status + reset pulse

RApR  equ  H'C3'  ; 0xc3 + addr + data + .. + reset pulse
        ; application register --> master  ( locked)
        ; register scratchpad  --> master  ( not lock)
LockAp  equ  H'5A'  ; 0x5A + 0xa5 
        ; [ register scratchpad --> application register]
        ; 0x5A + reset pulse CANcel copy command
        ; a OTP type do once only
      
      
AppLocked equ  B'11111100' ; application locked, the value is data in the status
        
       

;; ROM function command// implement skip rom only

SkipROM  equ  H'CC' ;access memory directly
SerachROM equ  H'f0' ;read a bit , read the complement of the bit,write bit
MatchROM equ  H'55' ;0x55 + 64 bit rom bit  
ReadROM  equ  H'33' ;[family code & serial number & CRC ==> master ]
 
  org  H'00'
  nop
  goto main
  
;;ISR  **
  org  H'04'
  goto isr  
isr 
  movwf W_SAVE    ;; W_SAVE=W
  swapf STATUS,W  ;; 
  movwf STATUS_SAVE  ;; STATUS_SAVE=STATUS[3:0]& STATUS[7:4]
  btfss PIR1,TMR1IF  ;; TMR1IF
  goto exit_int_source_check
          ;; timer 1 service          
  nop
  nop
  nop
  nop
          
          
exit_int_source_check    ;; restore STATUS & W before exit from 
  swapf STATUS_SAVE,W  ;; W=STATUS_SAVE=STATUS[3:0]& STATUS[7:4]
  movwf STATUS    
  swapf W_SAVE,F  ;; restore W
  swapf W_SAVE,W          
  retfie
;; ISR  &&&  
main          
  
  call init
  call init_int_en

  movlw H'21'
  movwf FSR
  movlw H'3c'
  movwf INDF    ;
;-----------------------------------------------  
;---------  read test --------------------------  
;-----------------------------------------------
;  movlw H'00'
;  banksel Addr
;  movwf Addr 
;  call RdDS2430
  
;  movlw H'01'
;  banksel Addr
;  movwf Addr 
;  call RdDS2430
;  
;  movlw H'02'
;  banksel Addr
;  movwf Addr 
;  call RdDS2430
;------------------------------------------------  
;  banksel Offset
;  clrf Offset 
;  pagesel VendorTable 
;  call VendorTable
;  movwf Temp
;  
;
  
  movlw H'00'
  banksel Addr
  movwf Addr  
  movlw H'34'
  banksel TxBuffer
  movwf TxBuffer
  call WrDS2430
  
  movlw H'01'
  banksel Addr
  movwf Addr
  movlw H'35'  
  banksel TxBuffer
  movwf TxBuffer
  call WrDS2430  
  
  movlw H'02'
  banksel Addr
  movwf Addr
  movlw H'36'
  banksel TxBuffer
  movwf TxBuffer
  call WrDS2430  
  
    
;-------- read address 0 --------------------------  
  movlw H'00'
  movwf Addr 
  call RdDS2430
  
  goto $    
;----------------------------------------------
; template to init before write
; to DS2430
;-----------------------------------------------  
;  movlw H'00'
;  movwf Addr  
;  movlw H'3C'
;  movwf TxBuffer  
  
;---------------------------------------------
; write DS2430 one byte
; input
; Addr = starting address to write
; TxB  = data to save
; output = 
; ErrCode = 0 -> write ok
;  = 1 -> write fail
;----------------------------------------------- 
WrDS2430  
  call WrScratchPAD
  call CP2EE
  return

;------------------------------------------------
; template to init before read
; to DS2430
;-------------------------------------------------  
;   movlw H'00'
;  movwf Addr  

;-------------------------------------------------
; read DS2430 one byte
; input
; Addr = starting address to read
; output
; RxB  = data to read
;--------------------------------------------------
RdDS2430
  call REE2ScratchPAD  
  call HostRdScratchPAD
  return

;;---------  host read scratch pad ----------------------------
;; save desired data into RxB
;;
;;--------------------------------------------------------------
  
HostRdScratchPAD
  call  DS2430AInitState
  banksel TxB
  movlw SkipROM
  movwf TxB  
  call  TxBYTE    ; SkipROM
  
  movlw RScratch   ; read scratch PAD Command
  movwf TxB
  call TxBYTE
  
  movf Addr,W    ; starting address to read
  movwf TxB
  call TxBYTE
    
  call R2430A    ; read desired scratch pad into RxB
  call    RstPulse 
  return
  
  
;-------------- write memory scratch scratch pad ------------------------
; write one byte into scratch PAD
; input
; Addr   = starting address to write
; TxBuffer = data to save
; output 
; ErrCode = 0 -> write ok
;   = 1 -> write fail
;---------------------------------------------------------------------------

WrScratchPAD
  call DS2430AInitState
  movlw SkipROM    ; 0xCC
  movwf TxB
  call  TxBYTE    ; SkipROM
  
  movlw WScratch   ; write memory scratch pad, 0x0f
  movwf TxB
  call TxBYTE
  
  movf Addr,W    ; starting address of memory scratch pad
  movwf TxB     ; TxBYTE use TxB
  call TxBYTE
  
  movf TxBuffer,W   ; 
  movwf TxB
  call TxBYTE    
  call RstPulse   ; reset pulse
  call delay500us   ; wait presence pulse    
  return  
  
;---------- CP2EE ---copy whole scratch pad to EE ----------------------
;  write memory scratch
;  verify memory scratch
;  copy memory scratch to EE
;----------------------------------------------------------------------
CP2EE
  call  DS2430AInitState ; 0x55 + 0xa5 + hi 10ms // [ScratchPad -> EEPROM ]  
  banksel TxB
  movlw SkipROM
  movwf TxB  
  call  TxBYTE    ; SkipROM
  movlw CPScratch   ; 0x55
  movwf TxB
  call TxBYTE
  movlw H'a5'
  movwf TxB
  call TxBYTE
  call ForceHi    ; min 10ms refter to datasheet
  return

;--------- REE2ScratchPAD --- copy whole EE to ScrathPAD ----------------
;  copy EE to whole memory scatch
;  read memory scratch 
;format I:  0xf0 + Addr +R +R + reset pulse, copy byte by byte
;format II:  0xf0 + Addr + reset pulse, copy whole
;------------------------------------------------------------------------
REE2ScratchPAD
  call  DS2430AInitState
  banksel TxB
  movlw SkipROM
  movwf TxB  
  call  TxBYTE    ; SkipROM
  movlw REEROM    ;; Read from EE into ScratchPAD
  movwf TxB
  call TxBYTE    ;;
  call    RstPulse   ;; copy all
  return
  
;----------R2430A ---- Host read the scratch PAD ------------------------
; Read 2430A Scratch PAD
; LSB first
;   save the result in RxB
;------------------------------------------------------------------------

R2430A               ; returns byte in RxB
  movlw .8
  movwf LoopCounter
        clrf RxB
RLoop
  call  SetLo   ;
        nop
  call  SetHi   ; it will pull up by resistor
  nop      ; delay to sample reliable bit
  nop
  nop
  nop
  nop
  nop
  nop
  nop
  nop
  nop
  nop  
        nop
        nop
        nop
        nop
        
        banksel PORTB
        movf PORTB,W
        movwf Temp
        btfss Temp,Bit2

  goto gLo
  bsf  CARRY
  goto rol
gLo  
  bcf  CARRY
rol  
  banksel RxB
        rrf  RxB,F
        call delay60us  ; tdrv + trelease
        banksel LoopCounter
        decfsz LoopCounter,F
        goto RLoop
        movf RxB,W   ; save the result in W
        return
   
;----------------------------------------------------------
; strong pull up
;
;----------------------------------------------------------
ForceHi

  bsf  PBDir,Bit2
  movf PBDir,W   ;; input

  banksel TRISB
  movwf TRISB   ;; set input, pull by external resistor
  call delay100ms
  bcf  PBDir,Bit2  ;; output
  movf PBDir,W
  movwf TRISB
        return
;-------------------------------------------------------------
; reset pulse
;
;--------------------------------------------------------------
RstPulse
  call SetHi 
  call SetLo
  call delay500us
  call    SetHi   ;Pull up by resistor
  return
;---------------------------------------------------------------
; reset pulse followed presence pulse
; 
;---------------------------------------------------------------
DS2430AInitState
        call SetHi
        call SetLo
        call delay500us   ; reset pulse
  call SetHi
  call delay500us   ; presence pulse, pull up by resistor
  return

;-----------------------------------------------------------------------
   
init
 movlw H'3f'
 movwf PBDir   ; 0x00111111
 banksel TRISB
 movwf TRISB   ; force all portC as input 
; movlw b'00000000'  ; GP2 pull-up,GP4 output
; movwf WPU    ; connect the D of DS2430A to Port A
;--------------------------------------------------------------------
;  toggle from bank0 to bank1
;   option register
;   7:  1: port A pull-up OFF, 0:port A pull-up ON
;   6:  1: rising INT , 0:fall INT
;   5:  1: T0CKI to TMR0, 0: internal cycle to TMR0
; 4:  1: Hi to Lo count 0: Lo to Hi count
; 3:  1: Precale to WDT 0: Prescale to TMR0
;   2:0 prescale value
;---------------------------------------------------------------------  
 movlw b'11000010'  ;; pull-up ON,rising INT, internal cycle to TMR0,Lo to Hi count,Pre to TMR0,1:8
 movwf OPTION_REG  ;; ,prescal over 8
 banksel INTCON
 clrf INTCON
 clrf PORTB
 movlw 0x07   ;; comparator off
 movwf CMCON   ;; comparator off 
 clrf TMR0

;;--------------------------------------------------------
;; 7: X
;; 6:    1: Timer1 on if T1G
;; 5:4   : 11:/8,10:/4,01:/2,00:/1
;;  3 :   1 LP for timer 1 on, 0: LP for timer1 of
;;  2 :   1 do not sync external , 0 sync external cLOCk
;; 1 :   1: clock source external , 0: clock source internal   
;; 0 :   1: enable timer 1 ,0: dISAble timer 1
;;---------------------------------------------------------
 
; movlw b'00000000'  ;x,no gate control,over 8,LP osc to timer1 off,x,internal clock,stop timer
; movwf T1CON
 movlw b'00111000'
 movwf T1CON
 clrf PIR1 
 return
 
;;------------------------- 
;; init interrup enable,
;;-------------------------
init_int_en 

 banksel INTCON
 bsf INTCON,GIE   ;; GIE=1
 bcf INTCON,PEIE   ;; 
 bcf INTCON,T0IE   ;; T0IE=1
 bcf INTCON,INTE   ;; GP2 interrupt enable
; bcf INTCON,RAIE   ;; dISAble GPIO port change interrupt

;------------------------------------------------
; clear int flag
;------------------------------------------------ 
 bcf INTCON,T0IF
 bcf INTCON,INTF
; bcf INTCON,RAIF 
 bcf PIR1,TMR1IF  
; movlw H'00'
; movwf INTCON

 banksel PIE1
 bcf PIE1,EEIE
 bcf PIE1,ADIE
 bcf PIE1,CMIE
 bsf PIE1,TMR1IE   ; enable Timer 1, timer 1 use as delay
 return 
   
;--------------------------------------------
; Tx BYTE to 2430A
; LSB first, MSB last
;--------------------------------------------
TxBYTE
 movlw .8
    movwf LoopCounter
    bcf  CARRY
RollTxB
 banksel TxB
 rrf  TxB,F
 btfss CARRY
 goto LoBit
 call TxHi
 goto bloop
LoBit 
 call TxLo
bloop 
 banksel LoopCounter
 decfsz LoopCounter,F
 goto RollTxB
    return

;;---------------------------------------------------------
TxL
 call SetLo
 call delay60us   ; min 60 us
    call SetHi
    nop       ; recovery time min 1us
    nop  
    return
;-----------------------------------------------------------
; tx hi
;-----------------------------------------------------------

TxHi:
 call SetLo    ;1us nop
 call SetHi
    call delay60us
    nop
    nop       ;recovery time min 1us
 return

;;---------------------------------------------------------------------------
;;  toggle the RC0 as input and the bus was pulLED up by externl resistor
;;  applICation default PCDir.Bit0 to output
;;---------------------------------------------------------------------------
SetHi:
  bsf  PBDir,Bit2
  movf PBDir,w
;  bsf  bank1
  banksel TRISB
  movwf TRISB
  return
;;----------------------------------------------------------------------------
;;  clear register file RC0
;;----------------------------------------------------------------------------

SetL
  banksel PORTB
  bcf  PORTB,Bit2  ; data lo
  bcf  PBDir,Bit2  ; direction out
  movf PBDir,W
  banksel TRISB
  movwf TRISB        
        return
        
;---------------------------
; fix delay 60 us
; 0xffff - 8 = 0xfff7
;---------------------------
delay60us
 banksel PIR1
 bcf  PIR1,TMR1IF
 movlw H'EE'
 movwf TMR1L
 movlw H'FF'
 movwf TMR1H
 bsf  T1CON,TMR1ON
 btfss PIR1,TMR1IF
 goto $-1
 bcf  T1CON,TMR1ON
 bcf  PIR1,TMR1IF
 return

;---------------------------
; fix delay 500 us
; 0xffff - 0x3e = 0xffc1
;---------------------------
delay500us

 banksel PIR1
 bcf  PIR1,TMR1IF 
 movlw H'C0'
 movwf TMR1L
 movlw H'FF'
 movwf TMR1H
 bsf  T1CON,TMR1ON
 btfss PIR1,TMR1IF
 goto $-1
 bcf  T1CON,TMR1ON
 bcf  PIR1,TMR1IF 
 return 
 
;---------------------------
; fix delay 100 ms
; 0xffff - 30d4 = 0xcf26
;---------------------------
delay100ms
 banksel PIR1
 bcf  PIR1,TMR1IF
 movlw H'26'
 movwf TMR1L
 movlw H'CF'
 movwf TMR1H
 bsf  T1CON,TMR1ON
 btfss PIR1,TMR1IF
 goto $-1
 bcf  T1CON,TMR1ON
 bcf  PIR1,TMR1IF 
 return   
 
 org  H'800'
VendorTable
 movf Offset,W  ; Save offset in Temp
 andlw H'ff'
 addwf PCL,f   ; PCL = PCL+Offset
  
 dt  "MiCallChip",0 
 end