SYNOPSIS

        use PINE64::MAX7219;

        my $max = PINE64::MAX7219->new(0,1,2);

        $max->turn_on(1);
        $max->set_scanlimit(1);
        $max->set_intensity('max');

        #display test (all on / all off))
        $max->disp_teston();
        sleep(2);
        $max->disp_testoff();

        #clockwise circles
        $max->clockwise_circles(10);

        #counter clockwise circles
        $max->countercw_circles(10);

        #print a sentence, 0.5sec / word
        $max->print_sentence("perl rules on pine64", 500000);

        #endless KnightRider effect!
        for(;;){
                $max->bullets_lrmid(1);
                $max->bullets_rlmid(1);
        }#end for

DESCRIPTION

This module is a driver for 8-digit seven-segment MAX7219 displays. It is implemented as bit-banged SPI. Using the object's methods, you can set the intensity of the display, print words, and cascade multiple displays. It also comes with several built-in effects.

Only three GPIO pins are required: SPI clk, SPI data, and SPI chip select. This modules uses the PINE64::GPIO numbering scheme.

METHODS

new($clock,$data,$chip_select)

Takes the GPIO pin numbers that will be used to inplement the bit-bang SPI interface to the MAX7219 as arguments. Returns an object to control an 8-digit display.

shift_in($leds, $digit, $n_cascaded, $delay, $latch_flag) This method is only used internally. It takes an array of a single seven-segment's LEDs, the digit position, the number of cascaded MAX7219 displays, a delay in usec (between SPI clock pulses), and a latch flag. Each individual letter of a word is shifted in one at a time. Once all the letters are shifted in, the latch_flag is set high, and displays the word.

load() This method is only used internally. It manipulates the chip select line, aka latch pin. When called, it will render what has been shifted into the display.

print_sentence($sentence, $delay, $clear_flag) Perhaps the most useful method. Takes a string, however long, and displays each word for $delay micro seconds. $sentence could be the text of an entire book. $clear_flag is not required.

print_interleaved($string1, $string2) This method is for use with two 8-digit displays cascaded. $string1 will be displayed in the first display, $string2 in the cascaded display.

turn_on($num_cascaded) Turns on the MAX7219 chip by writing to the turn on register. Takes the number of cascaded displays as an argument. Enter 1 if only using one display.

set_scanlimit($num_cascaded) Writes to the scan-limit register. Sets it up to use all 8-digits of the display. Takes number of cascaded displays an arg.

set_intensity($intensity); Adjusts the brightness of the display. Takes a string as an arg. Valid vlaues are: min, dim, mid, bright, max.

all_off($num_cascaded) Turns off all digits. Takes number of cascaded displays as an arg.

disp_teston() Turns on all segments on all digits.

disp_testoff() Turns off all segments on all digits.

clockwise_circles($number_iterations) Clockwise circles effect.

countercq_circles($number_iterations) Counter clockwise circles effects

bullets_lrtop($number_iterations) Knight-rider like bullets effect. Top row of horizontal LEDs of each digit move from right to left.

bullets_rltop($number_iterations) Knight-rider like bullets effect. Top row of horizontal LEDs of each digit move from left to right.

bullets_lrmid($number_iterations) Knight-rider like bullets effect. Mid row of horizontal LEDs of each digit move from left to right.

bullets_rlmid($number_iterations) Knight-rider like bullets effect. Mid row of horizontal LEDs of each digit move from right to left.

bullets_lrbot($number_iterations) Knight-rider like bullets effect. Bottom row of horizontal LEDs of each digit move from left to right.

bullets_rlbot($number_iterations) Knight-rider like bullets effect. Bottom row of horizontal LEDs of each digit move from right to left.