27976 Datasheet 27976, 27979, 27977 | P4-P6

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Serial_LCD_Demo.spin

For Parallax Serial LCDs 27976, 27977, 27979

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CON

_clkmode = xtal1 + pll16x

_xinfreq = 5_000_000

TX_PIN = 0

BAUD = 19_200

OBJ

LCD : "FullDuplexSerial.spin"

PUB Main

LCD.start(TX_PIN, TX_PIN, %1000, 19_200)

waitcnt(clkfreq / 100 + cnt) ' Pause for FullDuplexSerial.spin to initialize

LCD.str(string("Hello, this text will wrap."))

Moving the Cursor

When you send a character to the Serial LCD, it always displays at the current cursor position. There are

a few different ways to move the cursor on the Serial LCD display. After each character you send, the

cursor automatically moves over one position. Along with this, there is a standard set of cursor move

commands including Backspace, Carriage Return, and Line Feed.

The Backspace/Left command (Dec 8) moves the cursor one place to the left and the Right command

(Dec 9) moves the cursor one place to the right. These can be useful for moving the cursor around to

overwrite existing text. These commands wrap to the next line of the display, if necessary. The Line Feed

command (Dec 10) moves the cursor to the next line of the display without changing the horizontal

position of the cursor. The Carriage Return command (Dec 13) also moves the cursor to the next line, but

it moves the cursor to the leftmost position on that line as well. The Form Feed command (Dec 12) clears

the entire display and moves the cursor to the leftmost position on line 0, just like when you first turn on

the display. You will need to pause for 5mS in your code after sending the Form Feed command, to give

the Serial LCD time to clear the display. Except for Form Feed, none of these move commands affects the

characters on the display.

There are also direct move commands that you can use to move the cursor to any position on the display

with a single command. The commands in the range Dec 128 to 143 and Dec 148 to 163 move the cursor

to the 16 different positions on each of the two lines of the model 27976 and 27977 LCDs. The

commands in the range Dec 128 to 207 move the cursor to the 20 different positions on each of the four

lines of the model 27979 LCD.

Controlling the Display

You also have control over the various display modes of the Serial LCD. The display-off command (Dec

21) turns off the display so that all of the characters disappear. The characters aren’t erased from the

display, though, and you can even keep writing new characters to the display when it is turned off. A

trick to make a lot of text show up all at once, even at a slow baud rate, is to turn off the display and

then send all of your text. Then, when you turn the display on again, all of the text appears instantly.

The display-on commands (Dec 22 to 25) turn the display back on and also control whether you want to

display the cursor and/or make the cursor character blink. The cursor is the short bar that shows up

below the character at the current cursor position. The blink option makes that character blink on and off

repeatedly. You can turn the cursor and blink options on or off, in any combination, as listed in the

command set table. You can change the cursor and blink mode even if the display is already on; you

don’t need to turn it off and then back on again.

With models 27977 and 27979, you can also control the backlight of the display. The backlight lights up

the display so that it is easier to see in the dark. There are commands to turn the backlight on (Dec 17)

and off (Dec 18).

Custom Characters

The Serial LCD has the capability to store up to eight user-defined custom characters. The custom

characters are stored in RAM and so they need to be redefined if you turn off the power. You can display

the custom characters by sending the commands Dec 0 to 7, as shown in the command set table. The

custom character will display at the current cursor position.

The custom characters are five pixels wide by eight pixels high. Each of the characters is stored as a

series of eight data bytes where the low five bits of each byte represent a row of pixels in the character.

The high three bits of each byte are ignored. A bit value of one turns that pixel on (i.e. makes it black).

The bottom row of pixels is often left blank (all zeros) to make it easier to see the cursor.

To define a custom character, you will send a total of 9 bytes to the Serial LCD. The first byte needs to

be a valid define-custom-character command (Dec 248 to 255) and must be followed by eight data bytes

that define the pixels of the character. The Serial LCD will always use the next eight bytes it receives to

set the pixels of the character. The data bytes define the character starting at the topmost row of pixels,

as shown in the example code.

BASIC Stamp 2 Custom Character Example

Define a custom character using the code example below. First, set the baud rate on your Serial LCD to

19,200. Then, load the code below into your BASIC Stamp 2 and run it. You will see a diamond character

appear on the screen.

' {$STAMP BS2}

' {$PBASIC 2.5}

TxPin CON 0

Baud19200 CON 32

HIGH TxPin ' Set pin high to be a serial port

PAUSE 100 ' Pause for Serial LCD to initialize

SEROUT TxPin, Baud19200, [250] ' Define custom character 2

' Now send the eight data bytes

SEROUT TxPin, Baud19200, [%00000] ' %00000 =

SEROUT TxPin, Baud19200, [%00100] ' %00100 = *

SEROUT TxPin, Baud19200, [%01110] ' %01110 = * * *

SEROUT TxPin, Baud19200, [%11111] ' %11111 = * * * * *

SEROUT TxPin, Baud19200, [%01110] ' %01110 = * * *

SEROUT TxPin, Baud19200, [%00100] ' %00100 = *

SEROUT TxPin, Baud19200, [%00000] ' %00000 =

SEROUT TxPin, Baud19200, [2] ' Display the new custom character 2

Propeller™ P8X32A Example Code

Define a custom character using the code example below. First, set the baud rate on your Serial LCD to

19,200. Then, load the code below into your Propeller and load RAM or EEPROM. You will see a diamond

character appear on the screen. Note: the FullDuplexSerial.spin object is included with the Propeller Tool

software.

{{

Serial_LCD_Custom_Character.spin

For Parallax Serial LCDs 27976, 27977, 27979

}}

CON

_clkmode = xtal1 + pll16x

_xinfreq = 5_000_000

TX_PIN = 0

BAUD = 19_200

OBJ

LCD : "FullDuplexSerial.spin"

PUB Main

LCD.start(TX_PIN, TX_PIN, %1000, 19_200)

waitcnt(clkfreq / 100 + cnt) ' Pause for FullDuplexSerial.spin to initialize

LCD.tx(250) ' Define custom character 2

' Now send the eight data bytes

LCD.tx(%00000) ' %00000 =

LCD.tx(%00100) ' %00100 = *

LCD.tx(%01110) ' %01110 = * * *

LCD.tx(%11111) ' %11111 = * * * * *

LCD.tx(%01110) ' %01110 = * * *

LCD.tx(%00100) ' %00100 = *

LCD.tx(%00000) ' %00000 =

LCD.tx(2) ' Display the new custom character 2

Playing Music

The Serial LCD has a built-in piezoelectric speaker which can play musical notes. The LCD includes a

sophisticated music player enabling users to program songs and tunes. You can play musical notes by

sending three types of note commands (Dec 214 to 232), as shown in the command set table.

Set Length

The “set length” commands (Dec 208 to 214) determines the length of time each note will play for. This

value remains the same until another “set length” command is received. A note’s length can range from

a 1/64

note to a whole note. A whole note is 2 seconds long.

P1-P3 P4-P6 P7-P9 P10-P11

27976

Mfr. #:

Buy 27976

Manufacturer:

Parallax

Description:

LCD Character Display Modules & Accessories 2x16 Serial LCD Non Backlit Version

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