Old program question

Buck Rogers · 2006-01-27 06:57

Hello!
Sometime ago I retreived from either the N&V site or even around Parallax itself a series of example Stamp programs that will talk to LCD displays. Two are for the Stamp1, and one is for the Stamp2. All three use the parallel method rather then the serial method. However they were written for 16x1 displays. All I have here are 16x2 and 16x4 displays.

Would the program work with a 16x2? I am presenting it via the Code function here:

' Listing 1
' Nuts & Volts: Stamp Applications, September 1997
' -----[noparse][[/noparse] Title ]-----------------------------------------------------------
'
' File...... LCDDEMO1.BAS
' Purpose... Stamp 1 -> LCD (4-bit interface)
' Author.... Jon Williams
' E-mail.... [url=mailto:jonwms@aol.com]jonwms@aol.com[/url]
' Started... 16 JUL 1994
' Updated... 25 JUL 1997

' -----[noparse][[/noparse] Program Description ]---------------------------------------------
'
' This program demonstrates the various standard features of a 1x16 LCD
' display that uses the Hitachi HD44780 controller. 
'
' LCD Connections:
'
' LCD        (Function)         Stamp
' ---------------------         -----
' pin 1         Vss             Gnd
' pin 2         Vdd             +5
' pin 3         Vo              Gnd (or wiper of 10K pot)
' pin 4         RS              Pin 4
' pin 5         R/W             Gnd
' pin 6         E               Pin 5
' pin 7         DB0             Gnd
' pin 8         DB1             Gnd
' pin 9         DB2             Gnd
' pin 10        DB3             Gnd
' pin 11        DB4             Pin 0
' pin 12        DB5             Pin 1
' pin 13        DB6             Pin 2
' pin 14        DB7             Pin 4

' -----[noparse][[/noparse] Revision History ]------------------------------------------------
'
' 16 JUL 94 : Version 1.0 - compilation of code from last 3 months
' 08 AUG 96 : Trimmed code to save space -- no performance changes!
' 25 JUL 97 : Updated for Nuts & Volts

' -----[noparse][[/noparse] Constants ]-------------------------------------------------------
'
SYMBOL  RS      = 4                     ' Register Select (1 = char)
SYMBOL  E       = 5                     ' LCD enable pin (1 = enabled)
' LCD control characters
'
SYMBOL  ClrLCD  = $01                   ' clear the LCD
SYMBOL  CrsrHm  = $02                   ' move cursor to home position
SYMBOL  CrsrLf  = $10                   ' move cursor left
SYMBOL  CrsrRt  = $14                   ' move cursor right
SYMBOL  DispLf  = $18                   ' shift displayed chars left
SYMBOL  DispRt  = $1C                   ' shift displayed chars right
SYMBOL  DDRam   = $80                   ' Display Data RAM control
 
' -----[noparse][[/noparse] Variables ]-------------------------------------------------------
'
SYMBOL  char    = B1                    ' character sent to LCD
SYMBOL  index   = B2                    ' loop counter

' -----[noparse][[/noparse] EEPROM Data ]-----------------------------------------------------
'
 EEPROM ("THE BASIC STAMP!")     ' preload EEPROM with message

' -----[noparse][[/noparse] Initialization ]--------------------------------------------------
'
Init:   Dirs = %00111111                ' set 0-5 as outputs
 Pins = %00000000                ' clear the pins

' Initialize the LCD (Hitachi HD44780 controller)
'
LCDini: PAUSE 500                       ' let the LCD settle
 Pins = %0011                    ' 8-bit mode
 PULSOUT E, 1
 PAUSE 5
 PULSOUT E, 1
 PULSOUT E, 1
 Pins = %0010                    ' 4-bit mode
 PULSOUT E, 1
 char = %00001100                ' disp on, crsr off, blink off
 GOSUB LCDcmd                     
 char = %00000110                ' inc crsr, no disp shift
 GOSUB LCDcmd
 char = ClrLCD
 GOSUB LCDcmd

' -----[noparse][[/noparse] Main Code ]-------------------------------------------------------
'
Start:  FOR index = 0 TO 15
   READ index, char              ' get character from EEPROM
   GOSUB LCDwr                   ' write it
   PAUSE 50                      ' delay between chars
 NEXT
 PAUSE 2000                      ' wait 2 seconds
 char = CrsrHm                   ' move the cursor home
 GOSUB LCDcmd
 char = %00001110                ' turn the cursor on
 GOSUB LCDcmd
 PAUSE 500
 char = CrsrRt
 FOR index = 1 TO 15             ' move the cursor accross display
   GOSUB LCDcmd
   PAUSE 100
 NEXT
 FOR index = 14 TO 0 STEP -1     ' go backward by moving to
   char = DDRam + index          '  a specific address
   GOSUB LCDcmd
   PAUSE 100
 NEXT
 char = %00001101                ' cursor off, blink on
 GOSUB LCDcmd
 PAUSE 2000
 
 char = %00001100                ' blink off
 GOSUB LCDcmd
 FOR index = 1 TO 10             ' flash display
   char = char ^ %00000100       ' toggle display bit
   GOSUB LCDcmd
   PAUSE 250       
 NEXT
 PAUSE 1000
 FOR index = 1 TO 16             ' shift display
   char = DispRt
   GOSUB LCDcmd
   PAUSE 100
 NEXT
 PAUSE 1000
 FOR index = 1 TO 16             ' shift display back
   char = DispLf
   GOSUB LCDcmd
   PAUSE 100
 NEXT
 PAUSE 1000
 char = ClrLCD                   ' clear the LCD
 GOSUB LCDcmd
 PAUSE 500
 GOTO Start                      ' do it all over

' -----[noparse][[/noparse] Subroutines ]-----------------------------------------------------
'
' Send command to the LCD
'
' Load char with command value, then call
'
'   Clear the LCD............. $01, %00000001
'   Home the cursor........... $02, %00000010
'   Display control........... (see below)
'   Entry mode................ (see below)
'   Cursor left............... $10, %00010000
'   Cursor right.............. $14, %00010100
'   Scroll display left....... $18, %00011000
'   Scroll display right...... $1C, %00011100
'   Set CG RAM address........      %01aaaaaa (Character Generator)
'   Set DD RAM address........      %1aaaaaaa (Display Data)
'
' Display control byte:
'
'   % 0 0 0 0 1 D C B
'               | | +-- blink character under cursor (1=blink)
'               | +---- cursor on/off (1=on)
'               +------ display on/off (1=on)
'
' Entry mode byte:
'
'   % 0 0 0 0 0 1 X S
'                 | +-- shift display (S=1), left (X=1), right (X=0)
'                 +---- cursor move: right (X=1), left (X=0)
'
'
LCDcmd: LOW RS                          ' enter command mode
     '  then write the character
' Write ASCII char to LCD 
'
LCDwr:  Pins = Pins & %11010000         ' save 7, 6 and RS; clear bus
 Pins = char / 16 | Pins         ' output high nibble
 PULSOUT E, 1                    ' strobe the Enable line
 Pins = Pins & %11010000
 Pins = char & $0F | Pins        ' output low nibble
 PULSOUT E, 1
 HIGH RS                         ' return to character mode
 RETURN

And there it is. Also I've got a question regarding the references to how the stamp is connected. The RS pin on the LCD is going to Pin4 on the stamp. But so is DB7 pin on the LCD. Am I missing something here? Also I haven't tried the code yet. I am just searching for advice first.

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Buck Rogers

www.gregg.levine.name

Jon Williams · 2006-01-27 07:37

The docs for our LCD AppMod have BS1 code included, and that's a 2-line display.· The only difference between using 1-line and 2-line displays is an additional step in the initialization sequence that specifies multi-line mode.· I've attached the BS1 code.

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Jon Williams
Applications Engineer, Parallax

Jon Williams · 2006-01-27 07:47

Note that the pinout for the new program differs from the old -- I've attached a schematic of the LCD AppMod so that you can make the right connections.· You'll also want to do a 'net search for the Hitachi HD44780 documentation; that's what the code is based on.

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Jon Williams
Applications Engineer, Parallax

Chris Savage · 2006-01-27 15:19

Buck,

·· Since we sell a Parallel LCD still you can find the Hitachi Datasheet at the bottom of our product page.

http://www.parallax.com/detail.asp?product_id=603-00006

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Chris Savage
Parallax Tech Support
csavage@parallax.com

Jon Williams · 2006-01-27 15:21

Thanks, Chris, I didn't know we had that on our web site.

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Jon Williams
Applications Engineer, Parallax

Chris Savage · 2006-01-27 15:27

It's handy, since we have it, and I have had to refer to it myself on many occasions now that Serial LCDs are in such great supply.

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Chris Savage
Parallax Tech Support
csavage@parallax.com

Bamse · 2006-01-27 17:02

Great...

I had a 2x12 LCD I just could not get to work...
I hooked it up according to the diagram and used the code form the parallax webiste and it worked on the first try...

Thanks for the tip...

/Bamse

Chris Savage · 2006-01-27 17:10

I think most people will find that those docs should work on most Parallel Alphanumeric LCD Displays.· Obviously there may be a few exceptions, but I have a HUGE collection at home of surplus LCD displays from all kinds of manufacturers and every single one worked using that code and connection.· A few gave weird results because of the way they were mapped, but they all initialized and functioned as far as writing data to the display.

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Chris Savage
Parallax Tech Support
csavage@parallax.com

Old program question

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