NAME

    Device::Chip::MAX7219 - chip driver for a MAX7219

SYNOPSIS

       use Device::Chip::MAX7219;
       use Future::AsyncAwait;
    
       my $chip = Device::Chip::MAX7219->new;
       await $chip->mount( Device::Chip::Adapter::...->new );
    
       await $chip->power(1);
    
       await $chip->intensity( 2 );
       await $chip->limit( 8 );
    
       await $chip->displaytest( 1 );
       await $chip->shutdown( 0 );
    
       sleep 3;
    
       await $chip->displaytest( 0 );

DESCRIPTION

    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.

    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.

METHODS

    The following methods documented in an await expression return Future
    instances.

 write_bcd

       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.

 write_raw

       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.

 write_hex

       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.

 set_decode

       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.

 intensity

       await $chip->intensity( $value );

    Sets the intensity register. $value must be between 0 and 15, with
    higher values giving a more intense output.

 limit

       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.

 shutdown

       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.

 displaytest

       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.

AUTHOR

    Paul Evans <leonerd@leonerd.org.uk>