LCD Troubles

[knight]

Okay so I don't know what i'm doing wrong, but its not working, so I need the help of the forum.

I'm working on a firmware chip for serial and I2C for an LCD. Unfortunately I'm not even having any luck turning the LCD on. Its powering up and just producing a series of black boxes on the bottom row.

The code is hippy's code for parrallel interfacing to an LCD, modified slightly to take account of new reserved words and so on:

        SYMBOL  RS        = C.2         ; 0 = Command   1 = Data
        SYMBOL  E         = C.3        ; 0 = Idle      1 = Active
        SYMBOL  DB4       = C.4         ; LCD Data Line 4
        SYMBOL  DB5       = C.5         ; LCD Data Line 5
        SYMBOL  DB6       = C.6         ; LCD Data Line 6
        SYMBOL  DB7       = C.7         ; LCD Data Line 7

        SYMBOL  RSCMDmask = %00000000 ; Select Command register
        SYMBOL  RSDATmask = %00000100 ; Select Data register

        SYMBOL  getEEP       = b11
        SYMBOL  byteOut      = b12
        SYMBOL  rsbit     = b13

    PowerOnReset:

        GOSUB InitialiseLcd

    DisplayTopLine:

        EEPROM 6,("Hello")

        FOR getEEP = 6 TO 10
          READ getEEP,byteOut
          GOSUB SendDataByte
        NEXT

    MoveCursorToStartOfSecondLine:

        byteOut = $C0
        GOSUB SendCmdByte

    DisplayBottomLine:

        EEPROM 11,("World!")

        FOR getEEP = 11 TO 16
          READ getEEP,byteOut
          GOSUB SendDataByte
        NEXT

	Debug


        END

    InitialiseLcd:

        FOR getEEP = 0 TO 5
          READ getEEP,byteOut
          GOSUB SendInitCmdByte
        NEXT

        ' Nibble commands - To initialise 4-bit mode

        EEPROM 0,( $33 )    ; %0011---- %0011----   8-bit / 8-bit
        EEPROM 1,( $32 )    ; %0011---- %0010----   8-bit / 4-bit

        ' Byte commands - To configure the LCD

        EEPROM 2,( $28 )    ; %00101000 %001LNF00   Display Format
        EEPROM 3,( $0C )    ; %00001100 %00001DCB   Display On
        EEPROM 4,( $06 )    ; %00000110 %000001IS   Cursor Move

                            ; L : 0 = 4-bit Mode    1 = 8-bit Mode
                            ; N : 0 = 1 Line        1 = 2 Lines
                            ; F : 0 = 5x7 Pixels    1 = N/A
                            ; D : 0 = Display Off   1 = Display On
                            ; C : 0 = Cursor Off    1 = Cursor On
                            ; B : 0 = Cursor Steady 1 = Cursor Flash
                            ; I : 0 = Dec Cursor    1 = Inc Cursor
                            ; S : 0 = Cursor Move   1 = Display Shift

        EEPROM 5,( $01 )    ; Clear Screen

        RETURN

    SendInitCmdByte:

        PAUSE 15                        ; Delay 15mS

    SendCmdByte:

        rsbit = RSCMDmask               ; Send to Command register

    SendDataByte:

        pinsC = byteOut & %11110000 | rsbit ; Put MSB out first
        PULSOUT E,1                     ; Give a 10uS pulse on E
        pinsC = byteOut * %00010000 | rsbit ; Put LSB out second
        PULSOUT E,1                     ; Give a 10uS pulse on E


	debug

        rsbit = RSDATmask               ; Send to Data register next

        RETURN

I'm working without, unfortunately, the aid of a scope or anything similar, just my simple multimeter.

For the most part it seems to be working as expected, and if i measure the outputs on pinC at the end of the program, the match what i expect to see, except for DB4-7 which are all at +5 volts (when at the end i'd expect DB4 at +5 and DB5-7 at +0V)

I've checked my wiring and am as sure as i can be that it is correct. I've got the contrast set so that the black isn't hard on, allowing me to be reasonably sure its not just a contrast issue.

The LCD came from: http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=270751918039&ssPageName=STRK:MEWNX:IT

and its datasheet can be found here:
http://www.bonafide.com.hk/catalog/MC1602-18.pdf (yeah i know crap datasheet)

The controller is a KS0066U which i'm informed is compatible with the HD44780, however for reference datasheet for the KS0066U is here: javascriptpenreq('http://www.datasheetcatalog.org/datasheet/SamsungElectronic/mXuuzvr.pdf')

I'm using a 20X2 on veroboard, and yes i have checked for shorts between the tracks.

Any suggestions that anyone could make would be much appreciated.

 

[Svejk]

C.6 is input only on 20x2. Would be better to move to portB.

Edit: Also, the pins direction should be initialised.

 

[westaust55]

Ron Hackett has done pretty much the same for serial in with the 20X2 and detailed in his book:
PICAXE® Microcontroller Projects for the Evil Genius

See his website at: http://www.jrhackett.net/
Ron also keeps the code available on his website.

The first lines in the main part of the program are:

' ==================== Begin Main Program =====================

	dirsB = %10111111				' configure portB (B.6 is hserin pin)
	dirsC = %10111111				' configure portC ([B]C.6[/B] is input only)

 

[knight]

.....RTFM Knight.....

Thanks West.

And yeah I knew about setting the dirs, and had tried it with it, but no luck (makes sense of course, can't tell an input hardware pin to be an output pin in software no matter how hard i try)