Device::Chip::MAX7219 - chip driver for a MAX7219
my $chip = Device::Chip::MAX7219->new;
await $chip->mount( Device::Chip::Adapter::...->new );
await $chip->intensity( 2 );
await $chip->limit( 8 );
await $chip->displaytest( 1 );
await $chip->shutdown( 0 );
await $chip->displaytest( 0 );
This Device::Chip subclass provides specific communication to a Maxim Integrated MAX7219 chip attached to a computer via an SPI adapter. As the MAX7221 chip operates virtually identically, this chip will work too.
This module drives a single MAX7219 chip. For situations involving multiple chips daisy-chained together (such as on popular LED matrix display board modules) see instead Device::Chip::MAX7219Panel.
The reader is presumed to be familiar with the general operation of this chip; the documentation here will not attempt to explain or define chip-specific concepts or features, only the use of this module to access them.
The following methods documented in an await expression return Future instances.
await $chip->write_bcd( $digit, $val );
Writes the value at the given digit, setting it to BCD mode if not already so. $val should be a single digit number or string, or one of the special recognised characters in BCD mode of -, E, H, L, P or space. The value may optionally be followed by a decimal point ., which will be set on the display.
Switches the digit into BCD mode if not already so.
await $chip->write_raw( $digit, $bits );
Writes the value at the given digit, setting the raw column lines to the 8-bit value given.
Switches the digit into undecoded raw mode if not already so.
await $chip->write_hex( $digit, $val );
Similar to write_bcd, but uses a segment decoder written in code rather than on the chip itself, to turn values into sets of segments to display. This makes it capable of displaying the letters A to F, in addition to numbers, - and space.
await $chip->set_decode( $bits );
Directly sets the decode mode of all the digits at once. This is more efficient for initialising digits into BCD or raw mode, than individual calls to write_bcd or write_raw for each digit individually.
await $chip->intensity( $value );
Sets the intensity register. $value must be between 0 and 15, with higher values giving a more intense output.
await $chip->limit( $columns );
Sets the scan limit register. $value must be between 1 and 8, to set between 1 and 8 digits. This should only be used to adjust for the number of LED digits or columns units physically attached to the chip; not for normal display blanking, as it affects the overall intensity.
Note that this is not directly the value written to the LIMIT register.
await $chip->shutdown( $off );
Sets the shutdown register, entirely blanking the display and turning off all output if set to a true value, or restoring the display to its previous content if set false.
Note that this is not directly the value written to the SHUTDOWN register.
await $chip->displaytest( $on );
Sets the display test register, overriding the output control and turning on every LED if set to a true value, or restoring normal operation if set to false.
Paul Evans <firstname.lastname@example.org>
To install Device::Chip::MAX7219, copy and paste the appropriate command in to your terminal.
perl -MCPAN -e shell
For more information on module installation, please visit the detailed CPAN module installation guide.