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  1. #1
    Join Date
    Aug 2005
    Location
    Michigan, USA
    Posts
    222

    Default LCDOUT w/custom interface?

    Someone on another Forum asked me if it's possible to use the LCDOUT function with my old Novelty Serial LCD Interface (a simple 1-pin interface experiment inspired by the Predko 2-pin shift-register interface).


    The interface uses standard Async' Serial data but in a rather exotic format where each byte is sent as two bytes, one nybble per byte, along with the LCD 'RS' bit.

    Code:
    ;
    ;  host low level K8LH Novelty 12F635 Serial LCD Driver
    ;
    LcdCmd
            clrc                    ; C = RS = 0, 'command'           |B0
            skpnc                   ;                                 |B0
    LcdDat
            setc                    ; C = RS = 1, 'data'              |B0
            movwf   Temp            ; save data in WREG               |B0
            swapf   Temp,W          ; swap nybbles -> WREG            |B0
            call    LcdNyb          ; send left nybble                |B0
            movf    Temp,W          ; send right nybble               |B0
    LcdNyb
            andlw   0x0F            ; mask off left nybble            |B0
            skpnc                   ; RS = 0? yes, skip, else         |B0
            iorlw   b'11000000'     ; set the RS bits                 |B0
            btfss   PIR1,TXIF       ; transmit buffer empty?          |B0
            goto    $-1             ; no, branch, else                |B0
            movwf   TXREG           ; send byte                       |B0
            return                  ;                                 |B0
    Can the LCDOUT function use a custom driver like the one above (after being upgraded to catch the special $FE character)?

    Kind regards, Mike
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    Last edited by Mike, K8LH; - 20th September 2009 at 15:51.

  2. #2
    Join Date
    Nov 2003
    Location
    Wellton, U.S.A.
    Posts
    5,926

    Default

    I must be missing the point. If it is wired as shown just use the normal LCDOUT. ???

    How is the 2 pin or 1 pin thing you mention wired?
    Dave
    Always wear safety glasses while programming.

  3. #3
    Join Date
    May 2004
    Location
    NW France
    Posts
    3,541

    Default

    Hi, Dave

    I think this might be some kind of serial to parallell converter ... trying to use the minimum pin count device ...

    might be used for a very particular use ...

    The Question was " Can I use THAT with PBP "LCDOUT" Command ??? "

    so, the answer is NO ...

    May be some SEROUT2 with modifier for 4 bits data out ... ( to be confirmed )

    Alain
    ************************************************** ***********************
    Why insist on using 32 Bits when you're not even able to deal with the first 8 ones ??? ehhhhhh ...
    ************************************************** ***********************
    IF there is the word "Problem" in your question ...
    certainly the answer is " RTFM " or " RTFDataSheet " !!!
    *****************************************

  4. #4
    Join Date
    Nov 2003
    Location
    Wellton, U.S.A.
    Posts
    5,926

    Default

    Quote Originally Posted by Acetronics View Post
    May be some SEROUT2 with modifier for 4 bits data out ... ( to be confirmed )
    OK, I see what I was missing now. This is a LCD Backpack thing.
    Interesting...
    Dave
    Always wear safety glasses while programming.

  5. #5
    selina's Avatar
    selina Guest

    Default Re: LCDOUT w/custom interface?

    RA4 is an open drain output.
    You'll need a pull-up resistor on that pin.

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