4-line LCD Help - using PortA instead of B

[Tom Gonser]

OK, I have been going crazy on the 4-line LCD.. the book makes it look so easy.. I am trying to send it an initialization routine (which apparently I need to do?) This is a Crystalfontz unit which should be really nice... I attached the spec sheet in case an expert out there might be able to take a look. I am sure others will want to use these displays also.

http://www.crystalfontz.com/products...2004LYYBJP.pdf

In any event, I've taken all the advice here, and from the Mfg says I am seeing just what I should before it is initialized.. However I still get nothing on any LCD.. I *MUST* be doing something really stupid.

Here is the initialization routine I sent (which did nothing) - from page 17 of the LDC data sheet...


define LCD_DREG PORTA ' Set data pin of LCD to
define LCD_DBIT 0 ' PORTA.0-PORTA.3

define LCD_RSREG PORTA ' Set RS bit of LCD to
define LCD_RSBIT 5 ' PORTA.5

define LCD_EREG PORTA ' Set E bit of LCD to
define LCD_EBIT 4 ' PORTA.4

DEFINE LCD_LINES 4 ' 4 Lines LCD
define LCD_COMMANDUS 2000 ' Command delay time in uSec
DEFINE LCD_DATAUS 100 ' Data delay time in uSec

pause 20

low PortA.5 ' RS
' RW is held low on board
low PortA.3 ' db7
low PortA.2 ' db6
High PortA.1 ' db5
high PortA.0 ' db4

pause 20

low PortA.5 ' RS
' RW is held low on board
low PortA.3 ' db7
low PortA.2 ' db6
High PortA.1 ' db5
Low PortA.0 ' db4

pause 10

low PortA.5 ' RS
' RW is held low on board
high PortA.3 ' db7 - says "N" ??
high PortA.2 ' db6 - says "F"??
Low PortA.1 ' db5 - says "*" ??
Low PortA.0 ' db4 - says "*" ??

pause 2

low PortA.5 ' RS
' RW is held low on board
low PortA.3 ' db7
low PortA.2 ' db6
Low PortA.1 ' db5
Low PortA.0 ' db4

pause 1

low PortA.5 ' RS
' RW is held low on board
High PortA.3 ' db7
low PortA.2 ' db6
low PortA.1 ' db5
Low PortA.0 ' db4

pause 1

low PortA.5 ' RS
' RW is held low on board
low PortA.3 ' db7
low PortA.2 ' db6
low PortA.1 ' db5
Low PortA.0 ' db4
pause 1

low PortA.5 ' RS
' RW is held low on board
low PortA.3 ' db7
low PortA.2 ' db6
Low PortA.1 ' db5
High PortA.0 ' db4

pause 1

low PortA.5 ' RS
' RW is held low on board
low PortA.3 ' db7
low PortA.2 ' db6
High PortA.1 ' db5 - says "I/D" ??
High PortA.0 ' db4 - says "S" ??

pause 1

low PortA.5 ' RS
' RW is held low on board
low PortA.3 ' db7
low PortA.2 ' db6
low PortA.1 ' db5
Low PortA.0 ' db4

pause 1

for x = 1 to 100
lcdout $fe, 1
lcdout $fe, 2
LCDOUT "Hellow World"
pause 2000
next x

[NavMicroSystems]

Tom,

according to the datasheet the LCD has en embedded HD44780 (or compatible) controller.

with this controller you don't need to "manually" initialize the LCD.

The first LCDOUT command issued does all the initialisation for you.

assuming you have a 4k7 pull-up on RA4
the following should work on an 16F876(A)

DEFINE OSC 20          ' <-- set your clock speed here !

ADCON1=7               ' All Digital
 
DEFINE LCD_DREG PORTA  ' Set data pin of LCD to
DEFINE LCD_DBIT 0      ' PORTA.0-PORTA.3

DEFINE LCD_RSREG PORTA ' Set RS bit of LCD to
DEFINE LCD_RSBIT 5     ' PORTA.5

DEFINE LCD_EREG PORTA  ' Set E bit of LCD to
DEFINE LCD_EBIT 4      ' PORTA.4

DEFINE LCD_LINES 4     ' 4 Lines LCD

PAUSE 1000	       ' wait for LCD controller to start up	

Loop:

LCDOUT $FE,1	       ' clear display and move cursor home

PAUSE 500              ' wait for "CLEAR" command to complete

LCDOUT "HELLO WORLD"   ' print "HELLO WORLD" at current cursor position

PAUSE 1000             

GOTO LOOP

END

If there is still no success there is most likely something wrong with your LCD and/or your PIC.

[Tom Gonser]

Thanks very much!

I am going to assume the LCDs from Crystalfontz don't work then. I ran the program and got nothing. Everything else on the PIC works fine. I have tried both of the LCDs I got from them, and the most I can see is line 1 and line 3 lit up with squares if I vary Vo.

Does anyone have any good sources of 4x20 LCD displays?

Thanks,
Tom

[NavMicroSystems]

Does anyone have any good sources of 4x20 LCD displays?

Tom,
it depends on where you are based.

Over here a good 4x20 Backlit LCD will be EUR 20 - EUR 30.
I have a source for 4x27 LCDs (non backlit) at EUR 5

contact me via PM
and see this

[bbarney]

before writing off 2 lcd's why don't you try hooking them up to your printer port like this
http://www.myrolypoly.com/lcd_project/lcd_project.html
it's an easy to follow article,if they work that way you'll know for sure whether it's a code or pic problem or there both bad.digikey or mouser are good sources of lcd's.
good luck

[Tom Gonser]

Interestingly, I see that the Crystalfontz displays require a pretty substantial intitialization routine. I can't tell if that is the same as what PBP send as standard or not.

I downloaded a demo app, and it sets the bits E,RS,etc. high and low for about 10 seconds in a pattern that looks like it must be matching the tech notes for their displays. It takes the PC parallell port driver about 10 seconds to send all the bit settings, so I'd guess it is much more than 'standard'..

The Crystlfontz guys don't seem to be able to provide details about exactly WHAT bits need to be sent and in what order to initialize the LCD.

I think my time is better spent switching to an LCD that we KNOW works with PBP, which is too bad because CrystalFontz LCDs really look nice.

Thanks as ususal for all the help folks!

TG

[mister_e]

can you try something for me and post your results?

' place your LCD define here and all the others

pause 2000
FLAGS=0
pause 500
LCDOUT $fe,1
pause 500

start:
     LCDOUT $FE,1,"Hello"
     Here: goto Here

[Archilochus]

I just took a peek at the Hitachi 44780 LCD controller data sheet.
The initialization routine shown in the Crystalfontz part is the same - taken word-for-word from the Hitachi 44780 specs. So PBP should be initializing it properly.

Arch