2x16 Parallel LCD - Not working?

everest · 2009-08-25 00:55

I now have TWO 2x16 stock LCDs from Parallax. I've tried connecting both of them directly to the dedicated LCD connection on my professional development board, and connecting all three pins as indicated in the sample code for the LCD. . .and I see absolutely nothing on my LCDs. . .zippo. . .am I just missing something fundamental here???? Strange for something right out of the box on a dedicated development board all from the same manufacturer, with their own code to just not work. I suspect a bonehead move on my part!

-Jeff

Wolfbrother · 2009-08-25 17:26

Hi,

Did you set the serial rate with the two switches on the back of the LCD? There's also a pot on the back of the LCDs and it adjusts the contrast. Check that adjustment as well.

SRLM · 2009-08-25 18:13

@Wolfbrother

I don't have the parallel version (which I assume everest is talking about), but it appears that the baud isn't selectable. I think you're thinking of the serial LCD

@everest
Assuming that you're talking about the parallel LCD, according to the LCD datasheet you need to dedicate 7 I/O pins for four bit mode, which is what the sample code does. Have you used jumpers to connect all 7 pins?

Mike Green · 2009-08-25 18:33

Make sure the contrast potentiometer (near X1) is set properly. It may be that the LCD is working invisibly with no contrast.

everest · 2009-08-26 16:56

Thanks for the replies! I'm specifically referring to item # 603-00006, the Parallel LCD. I've tried the various adjustments (contrast, etc.) but I'll check again tonight just to be sure. Looking at the code, it looks to me like the unit is only using 3 pins (0, 2, and 3). I've pasted the code from Parallax below. . .it's just super simple. I'm using the recommended professional development board, which has a built in socket for the LCD, and then I've connected pins 0, 2, and 3 to the E, RW, and RS pins. . .

The program runs fine, but neither LCD does a darn thing. . . .

-Jeff

' =========================================================================
' File...... Parallel_LCD_2X16.bs2
' Purpose... Parallel LCD Display Demo
' Author.... Parallax, Inc.
' E-mail.... support@parallax.com
' {$STAMP BS2}
' {$PBASIC 2.5}
'

[noparse][[/noparse] Program Description ]

' This program demonstrates using a Hitachi-compatible Parallel LCD Display
' This code works with the BS2, BS2e and BS2sx
'

[noparse][[/noparse] I/O Definitions ]

E PIN 0 ' Enable Pin For LCD
RW PIN 2 ' R/W Pin For LCD
RS PIN 3 ' LCD Register Select
' 0 = Instruction, 1 = Text
'

[noparse][[/noparse] Variables ]

char VAR Byte ' Character To Send To LCD
inst VAR char ' Induction To Send To LCD
index VAR Word ' Character Pointer
temp VAR Byte ' Temp Variable
'

[noparse][[/noparse] EEPROM Data ]

DATA "Hello, this is the LCD demo." ' Message To Send To LCD
'

[noparse][[/noparse] Initialization ]

Initialize:
LOW RW ' Set LCD To Write Mode
OUTS = %0000000000000000 ' Set All Output Low
DIRS = %0000000011111111 ' Set I/O Direction
GOSUB Init_Lcd ' Initialize The LCD Display
'

[noparse][[/noparse] Program Code ]

Main:
FOR temp = 0 TO 27 ' 28 Characters
IF temp = 15 THEN ' Check For End Of Line
GOSUB Next_Line ' Jump To Next Line
ENDIF
READ temp, char ' Read Next Character From EEPROM
GOSUB Send_Text ' Send Character To LCD Display
NEXT
END
'

[noparse][[/noparse] Subroutines ]

Init_Lcd:
PAUSE 200
OUTS = %00110000 ' Reset The LCD
PULSOUT E,1 ' Send Command Three Times
PAUSE 10
PULSOUT E,1
PAUSE 10
PULSOUT E,1
PAUSE 10
OUTS = %00100000 ' Set To 4-bit Operation
PULSOUT E,1
Inst = %00101000 ' Function Set (2-Line Mode)
GOSUB Send_Inst
Inst = %00001110 ' Turn On Cursor
GOSUB Send_Inst
Inst = %00000110 ' Set Auto-Increment
GOSUB Send_Inst
Inst = %00000001 ' Clears LCD
GOSUB Send_Inst
Inst = 14 ' Set Cursor To Underline
GOSUB Send_Inst
RETURN
Send_Inst:
LOW RS ' Set Instruction Mode
OUTB = Inst.HIGHNIB ' Send High Nibble
PULSOUT E,1
OUTB = Inst.LOWNIB ' Send Low Nibble
PULSOUT E,1
HIGH RS ' Set LCD Back To Text Mode
RETURN
Send_Text:
OUTB = Char.HIGHNIB ' Send High Nibble
PULSOUT E,1
OUTB = char.LOWNIB ' Send Low Nibble
PULSOUT E,1
PAUSE 100
RETURN
Next_Line:
Inst = 128+64 ' Move Cursor To Line 2
GOSUB Send_Inst
RETURN

SRLM · 2009-08-26 18:14

Those three pins are just the ones named. It's not a requirement that pins be named, and indeed, the code appears to use eight pins. Specifically, look at lines like this:

OUTS = %00100000 ' Set To 4-bit Operation

everest · 2009-08-27 22:24

Ahh, thanks. . .I had to dig like *crazy* to come up with info on the OUTS, DIRS, etc commands. They don't appear in the command references in my editor, but I found some good references. I'll read up on those. Thanks!

-Jeff

rixter · 2009-09-02 03:05

Everest,

If you have the socket on your PD board for the connector, you wouldn't need to be connecting anything else to any pins on the BS as the E, RS and RW are included in the pins on the connector. Not sure if this is compounding your issue. Using the PDB socket or connecting to BS pins directly is an either-or thing. Actually, I'm not sure how you would have been able to do that anyway. Isn't the ribbon cable occupying any connections that the LCD has on it's rear? Or are you saying that you tried two different ways to hook it up.. once with the connector and once just using those three pins? I don't have a PDB, but hooking that LCD unit to the LCD connector should be using Stamp pins 0,2,3,4,5,6, & 7 in 4 bit mode, so you shouldn't be using those pins on the Stamp elsewhere for other purposes.

Rick

vaclav_sal · 2009-09-02 16:45

If your LCD modules are Hitachi compatible, and most are, they will run internal reset on power up. That is why you have 200 ms pause before the LCD initialization starts.
Put STOP after this 200 ms PAUSE.
Now you should be able to use the contrast adjustment to see the dots of the matrix characters. If you do not see any display at all you are probably missing the power connection.

Chris Savage · 2009-09-04 20:28

The code (and the LCD) actually requires 7 I/O lines (6 if you never need to read data back). Four are used for the 4-bit data D4-D7. The other three are the control lines like Enable, R/W and RS. R/W could be tied low in many applications to free up a pin. But if you change the pins being used you need to be aware of how that affects the code and what needs to be changed. Take care.

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Chris Savage

Parallax Engineering
50 72 6F 6A 65 63 74 20 53 69 74 65
·

blablabla · 2009-10-29 13:47

hello,

i got the same problem as everest·has got

i connected a HD44780 lcd display to a basic stamp2, but i didnt connect it·the way it says in the example.

i connected it like this :

LCD pin······· |·· BS2· pin

1···················· 23

2···················· 21

3···················· POT

4······················5

5····················· 20

6······················19

7····················· 23

8······················23

9····················· 23

10···················· 23

11···················· 6

12····················· 7

13······················ 8

14···················· 9

please help me, searched already on google , but i couldn´t find anything

blablabla · 2009-10-29 13:48

edit:

at the moment·the display shows· one line of blocks

Post Edited (blablabla) : 10/29/2009 2:00:38 PM GMT

blablabla · 2009-10-30 12:52

ok, now it is working proparly, but i dont know how to add a home-made character (made with the charater generator from parallax)

p.s.: sorry for my bad english, but im from germany

underworldman · 2010-05-10 19:39

blablabla?

What did you do? My parallel lcd is behaving in the exact same way. Were there any faults in your program or was it a connection issue? Please help me.

sam_sam_sam · 2010-05-11 12:35

 ' -----[noparse][[/noparse] EEPROM Data ]-----------------------------------------------------
CC0             DATA    LcdCC0, $10, $10, $10, $10, $10, $10, $10, $10 '[color=red] <<<<<........Here is where you put your homemadecharacter[/color]   CC1             DATA    LcdCC1, $18, $18, $18, $18, $18, $18, $18, $18 ' [color=red]<<<<<........(made with the charater >[/color]  
CC2             DATA    LcdCC2, $1C, $1C, $1C, $1C, $1C, $1C, $1C, $1C ' [color=red]<<<<<........                    > generator from parallax)
[/color]CC3             DATA    LcdCC3, $1E, $1E, $1E, $1E, $1E, $1E, $1E, $1E
CC4             DATA    LcdCC4, $1F, $1F, $1F, $1F, $1F, $1F, $1F, $1F

' -----[noparse][[/noparse] Initialization ]--------------------------------------------------
  HIGH LCD                              ' Setup Serial Output Pin
  PAUSE 100                             ' Give LCD Time To Settle
Download_Chars:
  FOR index = 0 TO 45                   ' Download Custom Characters [color=red]this # need to be adj for the  Characters you have 
[/color]    READ CC0 + index, work              ' Read EEPROM Data
    SEROUT LCD, Baud, [noparse][[/noparse]work]            ' Send To LCD CGRAM
  NEXT
  SEROUT LCD, Baud, [noparse][[/noparse]LcdOn1, LcdBLon]   ' Turn LCD Display & Backlight On
                                        ' Backlight Only On Backlit Models
  PAUSE 10                              ' Allow LCD Time To Settle

Or you use this

 ' {$STAMP BS2}
' {$PBASIC 2.5}
 
 
TxPin        CON       15
Baud19200    CON       32
 

SEROUT TxPin, Baud19200, [noparse][[/noparse]2]
 
HIGH TxPIN                            ' Set pin high to be a serial port
PAUSE 100                             ' Pause for Serial LCD to initialize
SEROUT TxPin, Baud19200, [noparse][[/noparse]250]        ' Define custom character 2

                                      ' Now send the eight data bytes
SEROUT TxPin, Baud19200, [noparse][[/noparse]%00000]     ' %00000 
SEROUT TxPin, Baud19200, [noparse][[/noparse]%00100]     ' %00100 
SEROUT TxPin, Baud19200, [noparse][[/noparse]%01110]     ' %01110 
SEROUT TxPin, Baud19200, [noparse][[/noparse]%11111]     ' %11111 
SEROUT TxPin, Baud19200, [noparse][[/noparse]%01110]     ' %01110 
SEROUT TxPin, Baud19200, [noparse][[/noparse]%11011]     ' %00100 
SEROUT TxPin, Baud19200, [noparse][[/noparse]%00000]     ' %00000 
SEROUT TxPin, Baud19200, [noparse][[/noparse]%00000]     ' %00000 
'SEROUT TxPin, Baud19200, [noparse][[/noparse]2]          ' Display the new custom character 2

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·Now wanting to learn Spin· Thanks for any·

·that you may have and all of your time finding them

·
·
·
·
Sam

Post Edited (sam_sam_sam) : 5/11/2010 12:50:37 PM GMT

2x16 Parallel LCD - Not working?

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