help with 4 x 20 LCD

[keithv]

sorry. I'm editing the format now.

[mpgmike]

Each line has its own address in the HD44780.

Line 1 = $80
Line 2 = $C0
Line 3 = $90
Line 4 = $D0

You would need RS = 0 to send a command and send your line address, then RS = 1 and send the string.

[keithv]

Each line has its own address in the HD44780.

Line 1 = $80
Line 2 = $C0
Line 3 = $90
Line 4 = $D0

You would need RS = 0 to send a command and send your line address, then RS = 1 and send the string.

I'm sorry. I'm not following. I think I understand how to move the cursor around. But what is RS? The register select bit? I'm not getting it to display anything even on lines 1 and 2. What would you do differently here to get it to display "hello" on line 1 and then "world" on line 2?

Lcdout $fe, 1   ' Clear screen   
     Pause 500       ' Wait .5 second   
     Lcdout "Hello"  ' Display "Hello"   
     Pause 500       ' Wait .5 second   
     Lcdout $fe, $c0, "World" ' Move to line 2  and display "World"   
     Pause 500       ' Wait .5 second

[Scampy]

I'm sorry. I'm not following. I think I understand how to move the cursor around. But what is RS? The register select bit? I'm not getting it to display anything even on lines 1 and 2. What would you do differently here to get it to display "hello" on line 1 and then "world" on line 2?

Lcdout $fe, 1   ' Clear screen   
     Pause 500       ' Wait .5 second   
     Lcdout "Hello"  ' Display "Hello"   
     Pause 500       ' Wait .5 second   
     Lcdout $fe, $c0, "World" ' Move to line 2  and display "World"   
     Pause 500       ' Wait .5 second

You forgot to designate the line one position

LCDOUT  $FE,1
lcdout  $FE,$80,"Hello"
pause 500
lcdout  $FE,$C0,"World"
pause 500

[richard]

LCDOUT $FE,1
lcdout $FE,$80,"Hello"

the $FE,$80 is tolally unnecessary , the $FE,1 not only clears the screen it homes the cursor to
line 1 pos 0 too

LCDOUT $FE,1:FLAGS=0:PAUSE 250:LCDOUT $FE,1:PAUSE 250 ' Initialize LCD

is a waste of code space and indicates that the power on lcd wait may be too short



Pause xxx ' Wait for LCD to start up
LCDOUT $FE,1

is adequate , I have had displays that need the pause xxx to be as long as 500mS


its also possible that the default config settings in your pic16f887.inc file don't match your setup

can you blink a led at defined rate correctly ?

[keithv]

its also possible that the default config settings in your pic16f887.inc file don't match your setup

can you blink a led at defined rate correctly ?

I added the address for good measure. No luck. I increased the start up wait time. No luck still. I added a blinking LED and that works - on for half a second, off for 1 second. Stuff highlighted in RED is what was added/changed.

TRISB = %00000000
pause 500
mainloop:   
     Lcdout $fe, 1                                 ' Clear screen   
     Pause 500                                     ' Wait .5 second   
     Lcdout $fe, $80, "Hello"                                ' Display "Hello"  
     PORTB.7 = 1                                      'LED on 
     Pause 500                                     ' Wait .5 second   
     Lcdout $fe, $c0, "World"                 ' Move to line 2  and display "World"  
     PORTB.7 = 0                                      'LED off 
     Pause 500                                     ' Wait .5 second   
Goto mainloop                                    ' Do it forever   
End

[richard]

wiring ?
contrast setting ?
unused data pins on lcd are grounded not left floating ?

[Scampy]

The following code works for me with a 4 x 20 LCD

;----[LCD ]---------------------------------------------------------------------

DEFINE LCD_DREG  PORTB           ' LCD Data port
DEFINE LCD_DBIT  0               ' starting Data bit (0 or 4)
DEFINE LCD_EREG  PORTB           ' LCD Enable port
DEFINE LCD_EBIT  5               '     Enable bit  (on EasyPIC 5 LCD)
DEFINE LCD_RSREG PORTB           ' LCD Register Select port
DEFINE LCD_RSBIT 4               '     Register Select bit   (on EasyPIC 5 LCD)
DEFINE LCD_BITS  4               ' LCD bus size (4 or 8 bits)
DEFINE LCD_LINES 4               ' number of lines on LCD
DEFINE LCD_COMMANDUS 2000        ' Command delay time in us 
DEFINE LCD_DATAUS 50             ' Data delay time in us 

LCDOUT $FE,1:FLAGS=0:PAUSE 250:LCDOUT $FE,1:PAUSE 250 ' Initialize LCD

Obviously change the port/pin assignments to match your hardware

To inform the LCD which line to start displaying text on use;

$fe,$80,
$fe,$C0,
$fe,$94,
$fe,$d4,