PIC to control NEXA remoteswitch

[Fredrick]

Yes, the Parallax transmitter and reciver works fine, no problem...
I can read data sheets!!!

But how do i send the same RF code that the NEXA remote controls sends to the NEXA remote swich.

I have seen other projects that sends NEXA RF code whit a PIC and a RF transmitter but thats in ASM code.

        extern  IntRet
;        extern  ReceiveB,RT1Ini,IntRet,TxCharB
        extern  STRTUP
;        extern  STRTUP,TBuffCB

        global  RFNIni,RFNTrns
;        global  RTTrnsB
        global  CCP1Int,CCP2Int

        include SYSTEM.INC      ;System definitions
        include P16C74A.INC     ;Definitions for PIC16C74A

;************************************************************************
;*                                                                      *
;* CONSTANTS                                                            *
;*                                                                      *
;* Constant definitions for this program module.                        *
;*                                                                      *
;************************************************************************

;
; Bittime definitions for NEXA RF transmitter
;
BITTIM1 equ     295             ;1/4 bittime
BITTIM2 equ     590             ;2/4 bittime
BITTIM3 equ     885             ;3/4 bittime
BITTIM4 equ     1180            ;4/4 bittime
BITTIMP equ     10240           ;Bittime for preamble
;BITTIME equ     590             ;Bittime for NEXA RF transmitter
BITTIME equ     295             ;Bittime for NEXA RF transmitter

;************************************************************************
;*                                                                      *
;* VARIABLES                                                            *
;*                                                                      *
;* Variable definitions for this program module.                        *
;*                                                                      *
;************************************************************************

RAM0    UDATA

TXCount res     1               ;Transmission counts
BCount  res     1               ;Transmit bit counter
XmtHldH res     1               ;Transmit/receive holding register high
XmtHldL res     1               ;Transmit/receive holding register low
XmtRegH res     1               ;Transmit/receive shift register high
XmtRegL res     1               ;Transmit/receive shift register low
BCountR res     1               ;Receive bit counter

XFlag   res     1

;************************************************************************
;*                                                                      *
;* FUNCTIONS                                                            *
;*                                                                      *
;* Functions for this program module.                                   *
;*                                                                      *
;************************************************************************

PROM    CODE

;
; Initalize device driver.
;
RFNIni  movlw   B'00000001'     ;Enable timer 1
        movwf   T1CON

        movlw   B'00001000'     ;CCP2 as output compare (pin RC1)
        movwf   CCP2CON

;        movlw   B'00000100'     ;CCP1 as input capture (pin RC2)
;        movwf   CCP1CON

        errorlevel  -302
        bsf     STATUS,RP0      ;Bank 1
;        bsf     PIE1,CCP1IE     ;Enable capture/compare 1 interrupt
        bsf     PIE2,CCP2IE     ;Enable capture/compare 2 interrupt
        bcf     STATUS,RP0      ;Bank 0
        errorlevel  +302
        return

;
; Transmitt data.
;
;  IN:  W = Data
;       FSR = Address
;  OUT: W,FSR destroyed
;
RFNTrns movwf   XmtHldH         ;Data
        movfw   FSR
        movwf   XmtHldL         ;Address
        swapf   XmtHldL,f
        movlw   4
        movwf   TXCount         ;Number of transmissions
        bsf     XFlag,0
        return

;
; Capture/compare 1 interrupt service routine.
;
CCP1Int bcf     STATUS,RP0      ;Bank 0
        bcf     PIR1,CCP1IF     ;Clear interrupt flag
        tstf    BCountR
        bnz     BitRead
;        movlw   low ( BITT15  ) ;Low byte of timer value (1.5 bittime)
        addwf   CCPR1L,w        ;Update low byte of compare register
        movwf   FSR             ;Use FSR for temp storage
;        movlw   high ( BITT15 ) ;High byte of timer value (1.5 bittime)
        btfsc   STATUS,C        ;Update high byte of compare register
        addlw   1               ;Add one for carry
        addwf   CCPR1H,f
        movfw   FSR
        movwf   CCPR1L
        btfbs   PORTC,2,IntRet  ;Verify startbit twice
        btfbs   PORTC,2,IntRet
        movlw   9
        movwf   BCountR
        movlw   B'00001010'     ;CCP1 as interrupt only
        movwf   CCP1CON
        goto    IntRet        

BitRead movlw   low ( BITTIME ) ;Low byte of timer value
        addwf   CCPR1L,w        ;Update low byte of compare register
        movwf   FSR             ;Use FSR for temp storage
        movlw   high ( BITTIME );High byte of timer value
        btfsc   STATUS,C        ;Update high byte of compare register
        addlw   1               ;Add one for carry
        addwf   CCPR1H,f
        movfw   FSR
        movwf   CCPR1L

        clrc
        btfsc   PORTC,2         ;Test receive bit (RC2)
        setc
;        rrf     XmtReg,f        ;Shift bit into receive register
        decfsz  BCountR,f       ;Increment bitcount
        goto    IntRet
        movlw   B'00000100'     ;CCP1 as input capture (pin RC2)
        movwf   CCP1CON
;        rlf     XmtReg,f        ;Stopbit -> carry
        bnc     FErr            ;Framing error if no stopbit

;        movfw   XmtReg          ;Read received character
        clrc
;        call    ReceiveB        ;Decode message. Complete ?
        goto    IntRet

FErr    setc
;        call    ReceiveB        ;Decode message. Complete ?
        goto    IntRet

;
; Capture/compare 2 interrupt service routine.
;
CCP2Int bcf     PIR2,CCP2IF     ;Clear interrupt flag
        bcf     STATUS,RP0      ;Bank 0

        btfbc   XFlag,0,C2Norm0 ;Exit if transmission disabled
        movfw   BCount
        bz      C2z1
        decfsz  BCount,f
        goto    C2z2
        decfsz  TXCount,f
        goto    C2z1
        bcf     XFlag,0
        goto    C2Norm0

C2z1    movfw   XmtHldH
        movwf   XmtRegH
        movfw   XmtHldL
        movwf   XmtRegL

        rlf     XmtRegL,f
        rlf     XmtRegH,f
        movlw   50
        movwf   BCount
        bsf     CCP2CON,CCP2M0  ;Send bit = 1

        movlw   low (BITTIMP)   ;Low byte of timer value (1/4 duty cycle)
        addwf   CCPR2L,w        ;Update low byte of compare register
        movwf   FSR             ;Use FSR for temp storage
        movlw   high (BITTIMP)  ;High byte of timer value
        goto    C2SetL

;        goto    C2Norm

C2z2    btfsc   BCount,0
        bcf     CCP2CON,CCP2M0  ;Send bit = 0
        btfss   BCount,0
        bsf     CCP2CON,CCP2M0  ;Send bit = 1

        bcf     STATUS,C        ;Bit = 0
        btfbc   BCount,1,???1
        btfbc   BCount,0,???3
        rrf     XmtRegH,f
        rrf     XmtRegL,f
        bcf     STATUS,C        ;Bit = 0
???3    btfsc   XmtRegL,0
        bsf     STATUS,C        ;Bit = 1
???1    btfbc   BCount,0,???2
        btfbs   STATUS,C,???4
???5    movlw   low (BITTIM1)   ;Low byte of timer value (1/4 duty cycle)
        addwf   CCPR2L,w        ;Update low byte of compare register
        movwf   FSR             ;Use FSR for temp storage
        movlw   high (BITTIM1)  ;High byte of timer value
        goto    C2SetL

???2    btfbs   STATUS,C,???5
???4    movlw   low (BITTIM3)   ;Low byte of timer value (1/4 duty cycle)
        addwf   CCPR2L,w        ;Update low byte of compare register
        movwf   FSR             ;Use FSR for temp storage
        movlw   high (BITTIM3)  ;High byte of timer value
        goto    C2SetL

C2Norm0 bcf     CCP2CON,CCP2M0  ;Send bit = 0
C2Norm  movlw   low (BITTIM2)   ;Low byte of timer value (1/4 duty cycle)
        addwf   CCPR2L,w        ;Update low byte of compare register
        movwf   FSR             ;Use FSR for temp storage
        movlw   high (BITTIM2)  ;High byte of timer value
C2SetL  btfsc   STATUS,C        ;Update high byte of compare register
        addlw   1               ;Add one for carry
        addwf   CCPR2H,f
        movfw   FSR
        movwf   CCPR2L
        goto    IntRet

[Archangel]

Yes, the Parallax transmitter and reciver works fine, no problem...
I can read data sheets!!!

OK, sorry, I thought that was what you were having trouble with. From fishing the internet this thing looks a lot like X10 controls, and I am guessing you want to control it without interfacing to a nexa transmitter, yes?

[Fredrick]

Yes i want to control it from the Parallax transmitter.

And yes the protocol seems to look like the X10 but there are some diffrents becouse the X10 funtion in PBP does´t work.

[Archangel]

And the assembly code posted above . . where did it come from, and do you have the include file system.inc? the other one I think comes from MPASM.
The web pages I visited list these for sale in Swedish speaking countries only. I think these are over my head, sorry.

[ardhuru]

Seeing the actual original signal would make it much easier, right?

Use the original transmitter, and a compatible RF receiver; feed the output to the soundcard and capture this signal, and study it using any sound editor (Audacity / Goldwave) (more details on this technique at Dave Houston's site).

It would then be much easier to replicate this signal.

Regards,

Anand

[dhouston]

Here's the URL that Anand referred to...

• http://davehouston.org/learn.htm

Once you capture the codes you merely need to duplicate the timing with your transmitter.

[Bruce]

Try something like this.

DEFINE OSC 4

' Timing as described in NexaProtocol.txt
T CON 350      ' T = 350uS
T3 CON 1050    ' 3T
T32 CON 11200  ' 32T (Stop/Synch)

' Note we're using 1 VS X as shown in text
A1_ON  CON %101100000000 ' 12-bit code for House/Unit A1 ON
A1_OFF CON %001100000000 ' 12-bit code for House/Unit A1 OFF
'           ||||||||||||____ 4-bit House code
'           ||||||||________ 4-bit Unit code
'           ||||____________ 3-bit Unknown code
'           |_______________ 1-bit Activation code 1=ON 0=OFF 

D_PACKET VAR WORD ' Holds 12-bit data packet to send
INDEX VAR BYTE    ' Data packet bit index pointer
LOOPS VAR BYTE    ' Loop counter

TX VAR PORTB.0    ' Connects to RF transmitter data in

LOW TX            ' TX output idles low for RF carrier OFF

Main:
    D_PACKET = A1_ON
    GOSUB Send
    PAUSE 5000
    D_PACKET = A1_OFF
    GOSUB Send
    PAUSE 5000
    GOTO Main
    
Send:
    FOR LOOPS = 1 TO 4    ' send each packet 4 times
      FOR INDEX = 0 TO 11 ' sends 12 bits per pass LSB 1st
        
        HIGH TX           ' The 1st half of a 0 or X  bit period is the
        PAUSEUS T         ' same so no need to repeat this sequence inside
        LOW TX            ' the IF block
        PAUSEUS T3 
        
        IF D_PACKET.0[INDEX]=1 THEN
           HIGH TX        ' send a 1 bit (1=X here)
           PAUSEUS T3
           LOW TX
           PAUSEUS T
        ELSE
           HIGH TX        ' send a 0 bit
           PAUSEUS T
           LOW TX
           PAUSEUS T3
        ENDIF
      NEXT INDEX          ' loop until all 12-bits sent
      
      ' Start of Stop/Synch period after each 12-bit packet
      HIGH TX
      PAUSEUS T
      LOW TX
      PAUSEUS T32
      ' End of Stop/Synch period
      
    NEXT LOOPS        ' send 4 packets per pass
    RETURN
      
    END

Can't say if this works or not since I don't have the receiver to play with, but it looks close
to what's shown in the NexaProtocol.txt timing diagram.