vfrico/LedControl-CommonAnode

LedPrint

An Arduino library for simple Arduino Print style use of 7-segment displays in Arduino using the MAX7219 and MAX7221 Led Display Drivers facilitating printing numbers, and appropriate letters to 7-segment displays, splitting displays into sub displays, and chaining drivers.

Derived from, and including, a modified LedControl library.

Table of Contents

• LedPrint
  • Features
  • Download, Install and Example
  • Simple Example
  • Full Class Reference

Features

Printing pretty much anything works the same as it would for, for example, Serial, since LedPrint derives from Print class just like Serial does.

// Strings
myDisplay.println("Hello");

// Flash strings
myDisplay.println(F("EARTH"));

// Integers
myDisplay.println(123);

// Floats
myDisplay.println(5.345, 3); // 3 dp

// Hex
myDisplay.println(456, HEX);

// Combining things
myDisplay.print(3);
myDisplay.println(" Volts");

// etc...

Using the special type LedPrintJustifiable we can justify our prints to the right or center

LedPrintJustifiable myDisplay = LedPrintJustifiable(11, 13, 10, 8); // 11 = data, 13 = clk, 10 = cs, 8 = number of digits

// Justify Left (default)
myDisplay.justify(-1);
myDisplay.println("Hello");

// Justify Right (1)
myDisplay.justify(1);
myDisplay.println(F("Earth"));

// Center Justify (0)
myDisplay.justify(0);
myDisplay.println("Arduino");

// Right justification with 0 padding
myDisplay.justify(1,0);
myDisplay.print(12);

Note that justification is fairly suboptimal, but works OK for typical update rates.

You can create sub-displays from your main display, that is you could split an 8 digit display into two 4 digit ones...

LedPrint displayA = myDisplay.getSubDisplay(0, 4); // 0 = first digit, 4 = number of digits
LedPrint displayB = myDisplay.getSubDisplay(4, 4); // 4 = first digit, 4 = number of digits

thereafter you can print to those sub displays

Note that the sub displays don't have to be contiguous, for example an 8 digit display made into a 3 digit one and a 2 digit one, the first 3 digits and the last 2 digits

LedPrint displayA = myDisplay.getSubDisplay(0, 3); // 0 = first digit, 3 = number of digits
LedPrint displayB = myDisplay.getSubDisplay(6, 2); // 6 = first digit, 2 = number of digits

Displays or sub-displays can be cleared

displayB.clear();

Intensity adjusted for the entire display (not individual subdisplays)

myDisplay.setIntensity(7);

The entire display can be shutdown

myDisplay.shutdown();

Or restarted

myDisplay.shutdown(false);

Download, Install and Example

• Download: http://sparks.gogo.co.nz/LedPrint.zip
• Open the Arduino IDE (this library was tested in 1.8.5, older versions may work)
• Select the menu item Sketch > Import Library > Add Library
• Choose to install the LedPrint.zip file you downloaded
• Now you can choose File > Examples > LedPrint > HelloWorld

Upload the example to your Arduino and stand back in awe of the results.

Simple Example

An 8 digit 7-segment Max7219 display is connected to pins 11 (data), 13 (clk), and 10 (chip select) of an Arduino, we print a message center-justified...

#include <LedPrint.h>

LedPrintJustifiable myLed = LedPrintJustifiable(11, 13, 10, 8); // 11 = data, 13 = clk, 10 = cs, 8 = number of digits

void setup()
{
  // Set Brightness
  myLed.setIntensity(5);
  
  // Center justify (0), alternatives -1 for left and 1 for right
  myLed.justify(0);
}

void loop()
{
  myLed.println("Hello");
  delay(3000);

  myLed.println("Earth");
  delay(3000);

  myLed.clear();
  delay(2000);      
}

Full Class Reference

I recommend to just look at the examples which show you how to use all the features, but if you want the nitty-gritty then here is the full class reference

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