Led.Digits

Rick Waldron edited this page Oct 26, 2016 · 20 revisions

The Led.Digits class constructs an object that may represent one or more (chained) 8 Digit, 7-Segment * LED Digit display (MAX7219/MAX7221) devices attached to the physical board. Up to 8 devices can be controlled with one instance, giving you 64 displayable digits.

* Support for varying segment devices is in progress.

Known supported devices:

(This list only represents devices that I've personally confirmed, please add devices as needed.)

Parameters

  • options An object of property parameters.

    Property Type Value/Description Default Required
    pins Object { data, clock, cs }. Object of digital pin names. yes
    pins Array [ data, clock, cs ]. Array of digital pin names. yes
    devices Number 1-8. For single device cases, this can be omitted. 1 no
    controller string HT16K33. The Name of the controller to use no

Shape

Property Name Description Read Only
isMatrix false. Yes
devices Number of devices controlled. Yes
digitOrder -1 or 1. -1 for RTL, 1 for LTR. No

Component Initialization

Shift Register Device

new five.Led.Digits({
  pins: {
    data: 2,
    clock: 3,
    cs: 4
  }
});

Led.Digits

HT16K33

new five.Led.Digits({
  controller: "HT16K33"
});

Led.Digits

Usage

var five = require("johnny-five");
var board = new five.Board();

board.on("ready", function() {

  var digits = new five.Led.Digits({
    pins: {
      data: 2,
      clock: 3,
      cs: 4
    }
  });

  digits.print("----");
});

API

NOTE: An Led.Digits instance can represent up to 8 chained devices (1 device can support up to 8 seven-segment digits), where each can be addressed directly by its device index in the chain (1-8).

NOTE: When the device is turned off (with the off method), data is retained and will be displayed on the device when turned on (with the on method). This is useful when powering the devices from a battery, by providing a power saving mechanism.

  • on() Turn on all digits devices.

  • on(device index) Turn on digits device at specified device index.

    // Turn on a specific device by device index.
    digits.on(0);
    
    // Turn on all devices
    digits.on();
  • off() Turn off all digits devices.

  • off(device index) Turn off digits device at specified device index.

    // Turn off a specific device by device index.
    digits.off(0);
    
    // Turn off all devices
    digits.off();
    
    // Send data to the the digits
    // ...Turn on the device to see the data displayed
  • clear() Shut off all LEDs, for all devices.

  • clear(device index) Shut off all LEDs, for a device at specified device index. (Note: clear() does not shut off the device.)

    // Clear the entire display of a specified device.
    digits.clear(0);
    
    // Clear the entire display for all devices
    digits.clear();
  • brightness(0-100) Set the brightness from 0-100%, of all devices.

  • brightness(device index, 0-100) Set the brightness from 0-100%, for a device at specified device index.

    // Set the brightness of a specified device.
    digits.brightness(1, 100);
    
    // Set the brightness for all devices
    digits.brightness(100);
  • draw(position, character) Draw a character to a digit position (0-7) on all devices.

  • draw(device index, position, character) Draw a character to a digit position (0-7) on a device at the specified device index.

    • This is probably not the API you want to use. See print(string) below

    • Valid character values:

      • A single number
      • A single number or character string
      • A string containing a number or letter character followed by a decimal point character.
      // Draw a "1" to device 1, digit position 0
      digits.draw(1, 0, "1");
      
      // Draw a "1" to all devices at digit position 0
      digits.draw(0, "1");

      // Draw an "A" to device 1, digit position 0
      digits.draw(1, 0, "A");
      
      // Draw an "A" to all devices at digit position 0
      digits.draw(0, "A");

      // Draw a "1." to device 1, digit position 0
      digits.draw(1, 0, "1.");
      
      // Draw a "1." to all devices at digit position 0
      digits.draw(0, "1.");

  • print(string) Display a string across available digits.

    • If a colon : is present on the display unit, then it is treated as a single character. That means that a 4 digit display that includes a colon will be treated as a 5 character display.

      digits.print("12:00"); // display the colon

      digits.print("12 00"); // do not display the colon

      digits.print("HOLA");

    • Periods following a digit are not considered a character, they are interpreted as being part of the preceding character.

      digits.print("0.0.0.0."); 

      digits.print("0.0.:0.0."); 

Predefined Characters

Led.Digits.DIGIT_CHARS

0 1 2 3 4 5 6 7 8 9   
! .
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
a b c d e f g h i j k l m n o p q r s t u v w x y z

Events

Led.Digits objects are output only and therefore do not emit any events.

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