4x20 display sample code

Aaron Wall · 2009-02-23 05:48

Does any one have a sample program with a stamp controlling the 4x20 display in the Accessory page? I learn much better by tinkering with code than reading through the manual.

Thanks,
Aaron

SRLM · 2009-02-23 06:31

Nearly every product Parallax sells has sample code available on the product page. Take a look there.

Aaron Wall · 2009-02-23 15:46

That was the first place I looked. They have 3 pdf files on there, but I didn't see anything about sample code.

sylvie369 · 2009-02-23 15:49

Hmm. On the product page for the 4x20 LCD I see

Parallax web gremlins said...
Downloads:
Parallax Serial LCD Documentation v2.0 (.pdf)
Javelin Stamp Example Code (.zip)
BASIC Stamp 1 and 2 Example Codes (.zip)
SX/B Serial LCD Demo (.SXB)

The BS1/2 .zip file contains several files of sample code. In addition, the .pdf has useful little code snippets - all I needed to figure the thing out - plus links to sample code.

Aaron Wall · 2009-02-24 05:12

Upon further investigation, there are two 4x20 displays on the list. I'm referring to the one with the keypad interface. The display design is more what I'm looking for.

Franklin · 2009-02-26 02:39

It looks like the code Sylvie pointed to will work for either.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Stephen

Steve88W · 2009-03-02 03:19

You can use my code to learn from.
I did not buy mine from Parallax, but it is a serial 4X20 LCD with keypad conrtoller built in so the code should work.

' Serial LCD Display project
' Steve White 2009
' LCD Module with I2C/Serial Interface and Keypad Control
' My examples have my output pin1 from the microcontroller to the RX pin on the LCD
' Make sure you have a fresh battery for the Basic Stamp!

' Visit http:\\www.stevesgeekprojects.blogspot.com for pictures of my LCD setup.

' {$STAMP BS2}
' {$PBASIC 2.5}

    'COMMANDS
'Prefix Command Parameter Description
'$FE    $00    null      No operation
'$FE    $01    1 Byte    Changing the I2C Slave Address
'$FE    $02    1 Byte    Changing BAUD Rate
'$FE    $03    1 Byte    Set Backlight Brightness
'$FE    $04    1 Byte    Set Contrast
'$FE    $05    None      Save Splash/Startup Screen
'$FE    $06    None      Display Firmware Version Number
'$FE    $07    None      Display Serial Baud Rate
'$FE    $08    None      Display I2C Address
'$FE    $09    Null      No operation
'$FE    $0A    None      Turn ON Display
'$FE    $0B    None      Turn Off Display
'$FE    $0C    2 bytes   Set Cursor Position
'$FE    $0D    None      HOME Cursor
'$FE    $0E    None      Turn ON Underline Cursor
'$FE    $0F    None      Turn Off Underline Cursor
'$FE    $10    None      Move Cursor Left One Space
'$FE    $11    None      Move Cursor Right One Space
'$FE    $12    None      Turn ON Blinking Cursor
'$FE    $13    None      Turn Off Blinking Cursor
'$FE    $14    None      Clear Screen
'$FE    $15    Variable  Print String
'$FE    $16    1 Byte    Init Horizontal Bar Graph
'$FE    $17    4 bytes   Draw Horizontal Bar Graph
'$FE    $18    None      Init Vertical Bar Graph
'$FE    $19    4 bytes   Draw Vertical Bar Graph
'$FE    $1A    9 bytes   Load Custom Characters
'$FE    $1B    None      READ Keypad

  'Brightness/Contrast
'Parameter     Length   Description
'[noparse][[/noparse]brightness]  1 Byte   Set backlight brightness (0 &#8211; 250)      $FE, $03
'[noparse][[/noparse]contrast]    1 byte   Set LCD contrast (0 &#8211; 100)              $FE, 04

'Set Cursor Position  $FE $0C [noparse][[/noparse]col] [noparse][[/noparse]row]  (0-3) AND col (0-19)
'Example:   SEROUT 1, 84, 25, [noparse][[/noparse]$FE, $0C, 2, 1, "text"]
'= transmit On PIN1, 9600 Baud, 25 type speed, row 3, col 2, LCD shows "text" On screen

'Clear Screen $FE $14
'Example: SEROUT 1, 84, [noparse][[/noparse]$FE $14]   where 1 is the pin and 84 is the baud rate

'<<<<<<<<<<<<<<<<< BEGIN TEXT CODE >>>>>>>>>>>>>>>>>>>>>>
PAUSE 2000    'I like to give the LCD 2 seconds to initialize
SEROUT 1, 84, [noparse][[/noparse]$FE, $0A]   'Ensures that the display is on
PAUSE 100
SEROUT 1, 84, [noparse][[/noparse]$FE, $14]    'Ensures that the screen is cleared
PAUSE 100
SEROUT 1, 84, [noparse][[/noparse]$FE, $03, 150] 'Sets the brightness (0-250)  *currently at 150
PAUSE 200
SEROUT 1, 84, 85, [noparse][[/noparse]"Hello World!"]    'Some text sent to the LCD, defaults to row 0, col 0
PAUSE 1500
SEROUT 1, 84, 25, [noparse][[/noparse]$FE, $0C, 1, 0, "This LCD is awesome"]  'Moves the cursor to row 2, col 1
PAUSE 1000
SEROUT 1, 84, 25, [noparse][[/noparse]$FE, $0C, 3, 1, "and easy to use"]      'Moves the cursor to row 4, col 2
PAUSE 1500        'waits 1.5 seconds
SEROUT 1, 84, [noparse][[/noparse]$FE, $14]  'Clears the screen
SEROUT 1, 84, 95, [noparse][[/noparse]$FE, $0C, 1, 2, "SLOW TEXT HERE"]     'the "95" is the type speed  (higher value = slower)
PAUSE 4000        'waits 4 seconds
SEROUT 1, 84, [noparse][[/noparse]$FE, $14]  'Clears the screen
PAUSE 200
'<<<<<<<<<<<<<<<<< END TEXT CODE >>>>>>>>>>>>>>>>>>>>>>

'<<<<<<<<<<<<<<<<< BEGIN ASCII ART CODE >>>>>>>>>>>>>>>
SEROUT 1, 84, [noparse][[/noparse]$FE, $0C, 0, 2,"    _     _ "]              'this area shows an ASCII image
SEROUT 1, 84, [noparse][[/noparse]$FE, $0C, 1, 2,"  o' ),=.( `o"]             'Check the manual to make sure the
SEROUT 1, 84, [noparse][[/noparse]$FE, $0C, 2, 2,"     (o-o)"]                'characters you are using are included on
SEROUT 1, 84, [noparse][[/noparse]$FE, $0C, 3, 2,"-ooO--(_)--Ooo-"]           'the LCD carrier board chip
PAUSE 2000
'<<<<<<<<<<<<<<<<< END ASCII ART CODE >>>>>>>>>>>>>>>>>

'<<<<<<<<<<<<<<<<< BEGIN GRAPH CODE >>>>>>>>>>>>>>>>>>>
' Ok, let's draw a Vertical Bar Graph
SEROUT 1, 84, [noparse][[/noparse]$FE, $14]    'Ensures that the screen is cleared
PAUSE 30
SEROUT 1, 84, 95, [noparse][[/noparse]$FE, $0C, 1, 3, "Vertical Bars"]
PAUSE 1500     '1.5 second pause
SEROUT 1, 84, [noparse][[/noparse]$FE, $14]    'Ensures that the screen is cleared
PAUSE 30
' Step One: Initialize the vertical bar graph code to the LCD  Command: $FE, $18
SEROUT 1, 84, [noparse][[/noparse]$FE, $18]
PAUSE 10
' Step Two: Tell the LCD where you want the bars  Command:  $FE $19 [noparse][[/noparse]Row 0-3][noparse][[/noparse]Col 0-19][noparse][[/noparse]Bar Height 1-4][noparse][[/noparse]Total Pixel Height 1-32]
SEROUT 1, 84, [noparse][[/noparse]$FE, $19, 3, 0, 4, 32]    'this is a full bar on the left side of the screen
PAUSE 1000     '1 second pause
SEROUT 1, 84, [noparse][[/noparse]$FE, $19, 3, 2, 3, 20]    'adding another 2 1/2 character tall bar with a 1 col space between
PAUSE 1000     '1 second pause
SEROUT 1, 84, [noparse][[/noparse]$FE, $19, 3, 4, 1, 8]    'adding one more bar, 1 box high and two col space from last
PAUSE 300
SEROUT 1, 84, [noparse][[/noparse]$FE, $19, 3, 10, 1, 8]
PAUSE 200
SEROUT 1, 84, [noparse][[/noparse]$FE, $19, 3, 12, 3, 20]
PAUSE 100
SEROUT 1, 84, [noparse][[/noparse]$FE, $19, 3, 14, 4, 32]
PAUSE 3000     '3 second pause

' Ok, let's draw a Horizontal Bar Graph
SEROUT 1, 84, [noparse][[/noparse]$FE, $14]    'Ensures that the screen is cleared
PAUSE 30
SEROUT 1, 84, 95, [noparse][[/noparse]$FE, $0C, 1, 2, "Horizontal Bars"]
PAUSE 1500     '1.5 second pause
SEROUT 1, 84, [noparse][[/noparse]$FE, $14]    'Ensures that the screen is cleared
PAUSE 30
' Step One: Initialize the Horizontal bar graph code to the LCD  Command: $FE, $16 (type = 0 for solid graph, 1 &#8211; for line graph)
SEROUT 1, 84, [noparse][[/noparse]$FE, $16, 0]
PAUSE 10
' Step Two: Tell the LCD where you want the bars  Command:  $FE $17 [noparse][[/noparse]Row][noparse][[/noparse]Col][noparse][[/noparse]Length in total bars][noparse][[/noparse]PixelColEnd]
SEROUT 1, 84, [noparse][[/noparse]$FE, $17, 0, 0, 20, 100]    'this is a full bar on the top of the screen
PAUSE 1000     '1 second pause
SEROUT 1, 84, [noparse][[/noparse]$FE, $17, 1, 2, 10, 45]    '2nd row 3 cols over and 45 total pixels long (the 10 shows the max characters it can take up to)
PAUSE 1000     '1 second pause
SEROUT 1, 84, [noparse][[/noparse]$FE, $17, 3, 4, 4, 17]    '4th row, 5th col, 4 max character spaces, 17 pixels long
PAUSE 3000     '3 second pause
'<<<<<<<<<<<<<<<<< END GRAPH CODE >>>>>>>>>>>>>>>>>>>>>>

'<<<<<<<<<<<<<<<<< BEGIN SCROLL CODE >>>>>>>>>>>>>>>>>>>>>>
MessageStart DATA @ 2, "Scrolling Message  "         ' Scrolling Message + two spaces
MessageEnd   DATA

cursorStartROW    VAR     Byte                  ' First character location
cursorStartCOL    VAR     Byte                  ' First character location
head           VAR     Byte                  ' Start of displayed text
tail           VAR     Byte                  ' End of displayed text
pointer        VAR     Byte                  ' EEPROM address pointer
character      VAR     Byte                  ' Stores a character

SEROUT 1, 84, [noparse][[/noparse]$FE, $0A]   'Ensures that the display is on
PAUSE 10
SEROUT 1, 84, [noparse][[/noparse]$FE, $14]    'Ensures that the screen is cleared
PAUSE 10

cursorStartROW = 1                 ' Rightmost character in window
cursorStartCOL = 19                ' Right side of start col
head = 0                                     ' Initialize head and tail
tail = 0                                     ' of message

DO WHILE tail < (MessageEnd - MessageStart)  ' Scrolling loop

  SEROUT 1, 84, [noparse][[/noparse]$FE, $0C, cursorStartROW, cursorStartCOL]    ' Place window's right
  SEROUT 1, 84, [noparse][[/noparse]$FE, $0B]                        ' Turn off the display
  PAUSE 40                                  ' Let characters fade away

  FOR pointer = head TO tail                 ' Print new characters
    READ pointer + MessageStart, character
    SEROUT 1, 84, [noparse][[/noparse]character]
  NEXT

  SEROUT 1, 84, [noparse][[/noparse]$FE, $0A]                        ' Turn display back on
  PAUSE 120                                  ' Give the characters some time

  cursorStartCOL = cursorStartCOL - 1 MIN 1      ' MIN (number) where number = stop column
  tail = tail + 1                            ' Increment tail pointer

  ' Increment head pointer if tail pointer > window width.
  IF tail > (22) THEN head = head + 1 ELSE head = 0       '(22) = length of text area

LOOP                'Loops until condition is met
PAUSE 2000          '2 second pause

'<<<<<<<<<<<<<<<<< END SCROLL CODE >>>>>>>>>>>>>>>>>>>>>>

'<<<<<<<<<<<<<<<<< BEGIN BLINK TEXT CODE >>>>>>>>>>>>>>>>>>>>>>
'To blink text is easy
blink VAR Byte              'create the variable
FOR blink = 1 TO 20
SEROUT 1, 84, [noparse][[/noparse]$FE, $14]    'Ensures that the screen is cleared
PAUSE 200
SEROUT 1, 84, [noparse][[/noparse]$FE, $0C, 1, 3, "BLINKING TEXT"]
PAUSE 200
blink = blink +1          'when the count reaches 20, the loop stops and goes to the next line
NEXT
PAUSE 2000    '2 second pause

'<<<<<<<<<<<<<<<<< END BLINK TEXT CODE >>>>>>>>>>>>>>>>>>>>>>

'Good Bye message
SEROUT 1, 84, [noparse][[/noparse]$FE, $14]    'Ensures that the screen is cleared
PAUSE 20
SEROUT 1, 84, 5, [noparse][[/noparse]$FE, $0C, 0, 0, "Thanks for watching!"]
PAUSE 20
SEROUT 1, 84, 5, [noparse][[/noparse]$FE, $0C, 1, 0, "For more info, go to"]
PAUSE 20
SEROUT 1, 84, 50, [noparse][[/noparse]$FE, $0C, 2, 0, "stevesgeekprojects."]
PAUSE 20
SEROUT 1, 84, 50, [noparse][[/noparse]$FE, $0C, 3, 6, "blogspot.com"]
PAUSE 4000     '3 second pause
SEROUT 1, 84, [noparse][[/noparse]$FE, $14]    'Ensures that the screen is cleared
PAUSE 20
SEROUT 1, 84, 5, [noparse][[/noparse]$FE, $0C, 1, 5, "Good Bye!"]
PAUSE 2000

' Now for some cleanup
SEROUT 1, 84, [noparse][[/noparse]$FE, $0B]   'Turns the text display off (not the backlight)
PAUSE 20

'<<<<<<<<<<<<<<<<< BEGIN BACKLIGHT FADE CODE >>>>>>>>>>>>>>>>>>>>>>
' These two variables are used to dim the LCD backlight
fade VAR Byte
brightness VAR Byte
brightness = 150                 'this was set at the begining of this code but it's now assigned to the variable
FOR fade = 0 TO brightness                         'Fades the LCD backlight to zero
SEROUT 1, 84, [noparse][[/noparse]$FE, $03, Brightness - fade] 'Sets the brightness (0-250)  *fades to 0 from whatever level it was
NEXT
PAUSE 10
'<<<<<<<<<<<<<<<<< END BACKLIGHT FADE CODE >>>>>>>>>>>>>>>>>>>>>>

' I noticed that the backlight is never truly 'off' but you can control that with another output pin from the microcontroller

END     'Puts the Basic Stamp into low power mode

If you have any questions, let me know.

ozarkshermit · 2009-03-29 22:04

Steve:

I have used some of your example code for the subject backpack, and it was very helpful.
One thing I have not been able to get to work is custom characters. I've tried every combination I can think of, but no success. A line or two of sample code would be appreciated.

That is a great backpack, by the way. I found it very easy to use.

Thanks. . . .

Ken

Steve88W · 2009-03-30 02:04

You'll need to read the manual for the LCD screen closely.

Here's an excerpt from my manual.
Load Custom Characters
Syntax hexadecimal 0xFE 0x1A [noparse][[/noparse]addr][noparse][[/noparse]d0 … d7]
Parameter Length Description
[noparse][[/noparse]addr][noparse][[/noparse]d0 … d7] 9 bytes Load custom characters,
[noparse][[/noparse]addr] 1 byte – custom character address from 0 to 7,
[noparse][[/noparse]d0 … d7] 8 bytes – custom character pattern bit map
14
Description: LCD module has space for 8 custom characters. Each custom character is 5 pixels
wide by 8 pixels high.
The [noparse][[/noparse]addr] parameter indicates which custom character is defining, and must have a value from 0
to 7.
Following the [noparse][[/noparse]addr] parameter are 8 bytes that define the custom character. Bits 0 to 4 each byte
byte will each define a pixel character.
Example: The bit map for character ‘X’.
Bit 7 6 5 4 3 2 1 0 Hex
Byte 1 0 0 0 1 0 0 0 1 0x11
Byte 2 0 0 0 0 1 0 1 0 0x0A
Byte 3 0 0 0 0 0 1 0 0 0x04
Byte 4 0 0 0 0 1 0 1 0 0x0A
Byte 5 0 0 0 1 0 0 0 1 0x11
Byte 6 0 0 0 0 0 0 0 0 0x00
Byte 7 0 0 0 0 0 0 0 0 0x00

Byte 8 0 0 0 0 0 0 0 0 0x00

4x20 display sample code

Comments