NAME
RPi::LCD - Perl interface to Raspberry Pi LCD displays via the GPIO
pins
SYNOPSIS
use RPi::LCD;
my $lcd = RPi::LCD->new;
my %lcd_args = (
rows => 2, # number of display rows, 2 or 4
cols => 16, # number of display columns 16 or 20
bits => 4, # data width in bits, 4 or 8
rs => 1, # GPIO pin for the LCD RS pin
strb => 2, # GPIO pin for the LCD strobe (E) pin
d0 => 3, #
... # d0-d3 GPIO pinout numbers
d3 => 6, #
d4 => 7, # set d4-d7 to all 0 (zero) if in 4-bit mode
... # otherwise, set them to their respective
d7 => 11, # GPIO pins
);
# initialize the LCD screen
$lcd->init(%lcd_args);
my $perl_ver = '5.24.0';
my $name = 'stevieb';
$lcd->home; # row 0, col 0
$lcd->print("${name}'s RPi, on");
$lcd->position(0, 1); # row 2
$lcd->print("Perl $perl_ver...");
DESCRIPTION
This module acts as an interface to typical 2 or 4 row, 16 or 20 column
LCD screens when connected to a Raspberry Pi.
It is standalone code, but if you access an instance of this class
through the RPi::WiringPi library, we'll ensure safe exit upon a crash.
METHODS
new()
Returns a new RPi::LCD object. We check if any RPi::WiringPi setup
routines have been run, and if not, we set up in GPIO pin mode.
init(%args)
Initializes the LCD library, and returns an integer representing the
handle (file descriptor) of the device. The return is supposed to be
constant, so DON'T change it.
Parameters:
%args = (
rows => $num, # number of rows. eg: 2 or 4
cols => $num, # number of columns. eg: 16 or 20
bits => 4|8, # width of the interface (4 or 8)
rs => $pin_num, # pin number of the LCD's RS pin
strb => $pin_num, # pin number of the LCD's strobe (E) pin
d0 => $pin_num, # pin number for LCD data pin 1
...
d7 => $pin_num, # pin number for LCD data pin 8
);
Mandatory: All entries must have a value. If you're only using four (4)
bit width, d4 through d7 must be set to 0.
NOTE: In 4-bit mode, connect to pins d4 - d7 on the LCD. These pins act
as d0 - d3 when not in 8-bit mode.
home()
Moves the LCD cursor to the home position (top row, leftmost column).
clear()
Clears the LCD display of all data, and return the cursor to the home
position.
display($state)
Turns the LCD display on and off.
Parameters:
$state
Mandatory: 0 to turn the display off, and 1 for on.
cursor($state)
Turns the LCD cursor on and off.
Parameters:
$state
Mandatory: 0 to turn the cursor off, 1 for on.
cursor_blink($state)
Parameters:
$state
Mandatory: 0 to stop blinking, 1 to enable.
send_cmd($command)
Sends any arbitrary command to the LCD. (I've never tested this!).
Parameters:
$command
Mandatory: A command to submit to the LCD.
position($x, $y)
Moves the cursor to the specified position on the LCD display.
Parameters:
$x
Mandatory: Column position. 0 is the left-most edge.
$y
Mandatory: Row position. 0 is the top row.
char_def($index, $data)
This allows you to re-define one of the 8 user-definable characters in
the display. The data array is 8 bytes which represent the character
from the top line to the bottom line. Note that the characters are
actually 5 � 8, so only the lower 5 bits are used. The index is from 0
to 7 and you can subsequently print the character defined using the
lcdPutchar() call.
Parameters:
$index
Mandatory: Index of the display character. Values are 0-7.
$data
Mandatory: See above description.
put_char($char)
Writes a single ASCII character to the LCD display, at the current
cursor position.
Parameters:
$char
Mandatory: A single ASCII character.
print_char($char)
Alias of put_char().
puts($string)
Parameters:
$string
Mandatory: A string to display.
print($string)
Alias of puts().
AUTHOR
Steve Bertrand, <
[email protected]>
COPYRIGHT AND LICENSE
Copyright (C) 2017 by Steve Bertrand
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself, either Perl version 5.18.2 or, at
your option, any later version of Perl 5 you may have available.
POD ERRORS
Hey! The above document had some coding errors, which are explained
below:
Around line 146:
Non-ASCII character seen before =encoding in '�'. Assuming UTF-8
