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lib/Device/Chip/MAX7219.pm  view on Meta::CPAN

   REG_DIGIT     => 0x01, # .. to 8
   REG_DECODE    => 0x09,
   REG_INTENSITY => 0x0A,
   REG_LIMIT     => 0x0B,
   REG_SHUTDOWN  => 0x0C,
   REG_DTEST     => 0x0F,
};

async method _writereg ( $reg, $value )
{
   await $self->protocol->write( chr( $reg ) . chr( $value ) );
}

=head1 METHODS

The following methods documented in an C<await> expression return L<Future>
instances.

=cut

=head2 write_bcd

   await $chip->write_bcd( $digit, $val );

Writes the value at the given digit, setting it to BCD mode if not already so.
C<$val> should be a single digit number or string, or one of the special
recognised characters in BCD mode of C<->, C<E>, C<H>, C<L>, C<P> or space.
The value may optionally be followed by a decimal point C<.>, which will be
set on the display.

Switches the digit into BCD mode if not already so.

=cut

async method write_bcd ( $digit, $val )
{
   $digit >= 0 and $digit <= 7 or
      croak "Digit must be 0 to 7";

   my $dp = ( $val =~ s/\.$// );
   length $val == 1 or
      croak "BCD value must be 1 character";
   ( $val = index "0123456789-EHLP ", $val ) > -1 or
      croak "Digit value '$val' is not allowed in BCD mode";

   my $decodemask = 1 << $digit;

   $_decode & $decodemask or
      await $self->set_decode( $_decode | $decodemask );

   await $self->_writereg( REG_DIGIT+$digit, $val + ( $dp ? 0x80 : 0 ) );
}

=head2 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.

=cut

async method write_raw ( $digit, $bits )
{
   $digit >= 0 and $digit <= 7 or
      croak "Digit must be 0 to 7";

   my $decodemask = 1 << $digit;

   $_decode & $decodemask and
      await $self->set_decode( $_decode & ~$decodemask );

   await $self->_writereg( REG_DIGIT+$digit, $bits );
}

=head2 write_hex

   await $chip->write_hex( $digit, $val );

Similar to C<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 C<A> to C<F>, in addition to
numbers, C<-> and space.

=cut

my %hex2bits;

async method write_hex ( $digit, $val )
{
   my $dp = ( $val =~ s/\.$// );
   my $bits = $hex2bits{$val} // croak "Unrecognised hex value $val";

   await $self->write_raw( $digit, $bits + ( $dp ? 0x80 : 0 ) );
}

=head2 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 C<write_bcd> or C<write_raw> for each digit individually.

=cut

async method set_decode ( $bits )
{
   await $self->_writereg( REG_DECODE, $_decode = $bits );
}

=head2 intensity

   await $chip->intensity( $value );

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

=cut