Controlling a 4x20 LCD (HD44780) in 4-bit mode using Perl

LCD.pm

To use the LCD package, tell your script to require it.

require LCD;

Create an LCD object instance using the default parameters. The default parameters are listed below.

• RS connected to Beaglebone pin P8_4
• E connected to Beaglebone pin P8_3
• Data 4 connected to Beaglebone pin P8_5
• Data 5 connected to Beaglebone pin P8_11
• Data 6 connected to Beaglebone pin P8_12
• Data 7 connected to Beaglebone pin P8_14

$lcd  = LCD->new();

To use a custom configuration, supply a hash to the constructor to override any of the defaults. Valid keys are RS, E, D4, D5, D6 and D7. Here are the sub-keys:

• gpio - GPIO bank label (not actually used for anything)
• header - GPIO header label (not actually used for anything)
• pin - PIN number for exporting
• mode - Declare the mode number of the GPIO pin (typically 7)
• mode0 - Declare the mode 0 name of the GPIO pin

my %CONFIG = (
        "RS" => {
                "gpio" => "GPIO1_7",
                "header" => "P8_4",
                "pin" => 39,
                "mode" => 7,
                "mode0" => "gpmc_ad7"
        },
        "E" => {
                "gpio" => "GPIO1_6",
                "header" => "P8_3",
                "pin" => 38,
                "mode" => 7,
                "mode0" => "gpmc_ad6"
        }
);

$lcd  = LCD->new(%CONFIG);

To display the configuration, use the configuration method.

$lcd->configuration; 

Use the set_position method to move the character position to a specific row and column (row, column).

$lcd->set_position(0, 0); 

Use the print method to write a string to LCD display.

$lcd->print("Beaglebone"); 

Use the close method to release (unexport) the GPIO configuration.

$lcd->close;