LCDOUT w/custom interface?

[Mike, K8LH]

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.

;
;  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

[mackrackit]

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?

[Acetronics2]

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

[mackrackit]

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...

[selina]

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