LCDOUT 4-bit data on 8-bit setting

[breesy]

Hey,

Im having trouble on a PIC16F88, as far as i can tell the code should be outputting the data on all eight pins of PORTB, but pins 4-7 are allways low, see the example below:

DEFINE OSC 8

Define LCD_DREG PORTB ' Port for LCD Data
Define LCD_DBIT 0 ' Starting Data bit (0 or 4) if 4-bit bus Use LOWER 4 bits of Port
Define LCD_RSREG PORTA ' Port for RegisterSelect (RS) bit
Define LCD_RSBIT 6 ' Port Pin for RS bit
Define LCD_EREG PORTA ' Port for Enable (E) bit
Define LCD_EBIT 7 ' Port Pin for E bit
Define LCB_BITS 8 ' Using 4-bit bus
Define LCD_LINES 4 ' Using 2 line Display
Define LCD_COMMANDUS 2000 ' Command Delay (uS)
Define LCD_DATAUS 200 ' Data Delay (uS)


init:
OSCCON = %01110000 '8 MHz Internal Oscillator
Pause 2000 'Safe Start Up Delay


CMCON = 7
ADCON1 = 7
ANSEL = %00000000
TRISA = %00000000
TRISB = %00000000
PORTA = %00000000
PORTB = %00000000

main:

LCDOUT %11111111
PAUSE 1000

goto main

end

Regards,
Daniel

[keithdoxey]

Define LCB_BITS 8 ' Using 4-bit bus

The comment doesnt match the parameter specified but the real problem is that you have typed LCB instead of LCD

Because you dont have a valid DEFINE it is using the default value which is for 4 bits.

Hope that helps

Keith

[breesy]

Thanks, that was it.. Its amazing how I could miss it after reading through the code so many times..

One more quick question, is it possible to clear a single line of an lcd display, or atleast fill it with blank characters?

[paul borgmeier]

or atleast fill it with blank characters?

Not efficient and code heavy but works – there must be a better way?

Line2Clr Var Byte
X var Line2Clr 'reuse variable with alias to save RAM

Line2Clr = 148 ' clear line 3 or 4x20 LCD (for example)
Gosub ClrLine

rest of program here

ClrLine: ' subroutine
  LCDOUT $FE,Line2Clr,32,32	' clear 148 and 149 with 32 (ascii blank)
  FOR X = 0 to 8 ' clear rest of line
    LCDOUT 32,32
  NEXT X
RETURN

Paul Borgmeier
Salt Lake City, Utah
USA

[keithdoxey]

Thanks, that was it.. Its amazing how I could miss it after reading through the code so many times..

We have all been there and done that in one way or another

One more quick question, is it possible to clear a single line of an lcd display, or atleast fill it with blank characters?

This is how I do it. I have a variable called "line" that I use for specifying which line of the LCD I want to go to the beginning of, and then specify CONstants for Line1, Line2 etc

This is the sub that I use to clear the LCD (actually it fills it with spaces)

       Line        var byte            ' Line of Display to act on
       Line1       con $02             ' Home position
       Line2       con $C0             ' Start of Line2

.......

        Line = Line2
        Gosub Blankline


.......

BlankLine:       ' **** This clears the whole line of the display ****
        LCDOut $FE, Line, REP " "\16 ' Send 16 spaces to clear the line
        Return   ' **** End of BlankLine ***

This could be extended further by changing the "16" to a variable name thereby giving the ability for a varying number of repeated characters.

You could go the whole hog and change it to LCDout $FE, Line,REP Char\Charcount
which would allow you to specify the Line, Character and number of characters to write to the display but I guess than you would have to call it something other than "Blankline"

[paul borgmeier]

BlankLine: ' **** This clears the whole line of the display ****
LCDOut $FE, Line, REP " "\16 ' Send 16 spaces to clear the line
Return ' **** End of BlankLine ***

Keith,
Nice and clean - sweet!

Paul

[keithdoxey]

Thanks Paul, but the only thing I can really take credit for is putting in a subroutine called "BlankLine". The syntax used is clearly shown on the LCDout page of the PBP manual