Parallax 4x20 Serial LCD (Backlit) Issue

chris jones

Hello i have a Parallax 4x20 Serial LCD (Backlit) and i have a few questions i have some demo code that parallax provided but i can not get it to work.Also how long can the basic stamp run with this huge lcd and backlight ?

CODE

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' =========================================================================
'
'·· File...... Serial_LCD_Terminal.BS2
'·· Purpose... Serial LCD Debug Terminal Demo
'·· Author.... (c) Parallax, Inc. -- All Rights Reserved
'·· E-mail.... support@parallax.com
'·· Started...
'·· Updated... 15 JUN 2009
'
'·· {$STAMP BS2}
'·· {$PBASIC 2.5}
'
' =========================================================================
'

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[noparse][[/noparse] Revision History ]

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' 06-15-2009:
' Added a 5 mS delay to commands sent via ESC so Clear Screen would work.

'

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[noparse][[/noparse] Program Description ]

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' Uses the BASIC Stamp debug terminal to send characters to
' the Serial LCD.
'
' Typed characters show up automatically on the display of
' the Serial LCD.
'
' To send a command with a specific value:
'·· * Press [noparse][[/noparse]Esc]"
'·· * Enter the value (0 to 255)
'·· * Press [noparse][[/noparse]Return]
'
' This second direct command mode enables sending of all the
' command codes, such as display on/off, cursor movement,
' and custom characters. Note that decimal, hexadecimal, and
' even binary input may be used.

'

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

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TX············· PIN···· 15·············· ' serial output to LCD

'

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[noparse][[/noparse] Constants ]

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#SELECT $STAMP
· #CASE BS2, BS2E, BS2PE
··· T2400······ CON···· 396
··· T9600······ CON···· 84
··· T19K2······ CON···· 32
· #CASE BS2SX, BS2P
··· T2400······ CON···· 1021
··· T9600······ CON···· 240
··· T19K2······ CON···· 110
#ENDSELECT
LcdBkSpc······· CON···· $08············ ' move cursor left
LcdRt·········· CON···· $09············ ' move cursor right
LcdLF·········· CON···· $0A············ ' move cursor down 1 line
LcdCls········· CON···· $0C············ ' clear LCD (use PAUSE 5 after)
LcdCR·········· CON···· $0D············ ' move pos 0 of next line
LcdBLon········ CON···· $11············ ' backlight on
LcdBLoff······· CON···· $12············ ' backlight off
LcdOff········· CON···· $15············ ' LCD off
LcdOn1········· CON···· $16············ ' LCD on; cursor off, blink off
LcdOn2········· CON···· $17············ ' LCD on; cursor off, blink on
LcdOn3········· CON···· $18············ ' LCD on; cursor on, blink off
LcdOn4········· CON···· $19············ ' LCD on; cursor on, blink on
LcdLine1······· CON···· $80············ ' move to line 1, column 0
LcdLine2······· CON···· $94············ ' move to line 2, column 0
Esc············ CON···· 27

'

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[noparse][[/noparse] Variables ]

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charIn········· VAR···· Byte··········· ' input from user
baud··········· VAR···· Word··········· ' baud rate for Serial LCD

'

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[noparse][[/noparse] Initialization ]

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Reset:
· HIGH TX······························ ' setup TX pin for LCD
· PAUSE 100···························· ' allow LCD to intialize
Menu:
· DEBUG CLS,
······· "Parallax Serial LCD", CR,
······· "

---

", CR,
······· CR,
······· "Select LCD baud rate:", CR,
······· "[noparse][[/noparse]1] 2400", CR,
······· "[noparse][[/noparse]2] 9600", CR,
······· "[noparse][[/noparse]3] 19200"
· DEBUGIN charIn
· SELECT charIn························ ' set baud to user selection
··· CASE "1"
····· baud = T2400
··· CASE "2"
····· baud = T9600
··· CASE "3"
····· baud = T19K2
··· CASE ELSE
····· GOTO Menu························ ' selection was invalid
· ENDSELECT

'

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[noparse][[/noparse] Program Code ]

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Main:
· SEROUT TX, baud, [noparse][[/noparse]LcdOn3, LcdCls]···· ' cursor on, clear display
· DEBUG CLS,
······· "Just type to send a character to the Serial LCD, or", CR,
······· "To enter a value directly:", CR,
······· "-- Press [noparse][[/noparse]Esc]", CR,
······· "-- Enter the value (0 to 255)", CR,
······· "-- Press [noparse][[/noparse]Enter]"
· DO
··· DEBUG CRSRXY, 0, 6, ">> ", CLREOL·· ' display char prompt
··· DEBUGIN charIn····················· ' get a character
··· IF (charIn = Esc) THEN
····· DEBUG CRSRXY, 0, 6, "># ", CLREOL ' display number prompt
····· DEBUGIN NUM charIn··············· ' accept number, any format
··· ENDIF
··· SEROUT TX, baud, [noparse][[/noparse]charIn]·········· ' send char/num to LCD
··· PAUSE 5
· LOOP
· END

END OF LINE

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Franklin

How do you have the two connected and have you tried adjusting the contrast? What happens when you run the code? Where are you getting power for the lcd? The stamp should run as long as there is power because it is only communicating to the lcd by serial and it can do that all day.

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- Stephen

chris jones

yes there is power to the lcd but it just shows

LCD DISPLAY
parallax
www.parallax.com

after a few minutes a pac man starts eating the leters

Moskog

Look at the manual at this link:

http://www.parallax.com/Portals/0/Downloads/docs/prod/audiovis/SerialLCD-v2.0.pdf

On page 5 you will find explanation of the DIP switches on the rear side of the display. Your display is probably in TEST-mode!