DMD2 is an Arduino library designed as an updated replacement for the original DMD library. Both libraries are designed for use with the Freetronics Dot Matrix Display.

This library is currently in BETA release meaning the documentation is incomplete, and the implementation may contain bugs. If you want the stable version, please use the original DMD library for now not DMD2.

If you find any bugs, please use the Issues feature in github to report them or post on the Freetronics Dot Matrix Display forum.

Changes from DMD library

The DMD2 library includes the following new features:

• Supports Arduino Due (IDE 1.5.6 or newer), as well as AVR-based Arduinos.
• Adds new "SoftDMD" support, which allows the standard DMDCon board connections to be used on all standard Arduino compatible models - including Arduino Mega/EtherMega, Arduino Due/EtherDue or Arduino Leonardo.
• Integrated timer management for simpler sketches.
• Improved performance, on an AVR-based Arduino a single DMD panel uses approximately 5-6% CPU overhead to update (including when using the SoftDMD mode rather than hardware SPI.)
• New drawString() methods accept flash strings, or the Arduino String type, directly. See the "AllDrawingOperations" example.
• New DMD_TextBox class supports automatic scrolling, and automatic print() interface for writing out numbers, variables, etc. See "Countdown" and "ScrollingAlphabet" examples.
• New dmd.setBrightness() call allows changing DMD brightness (no more blindingly bright displays!)
• New DMDFrame base class allows direct swapping of the DMD framebuffer, supporting double buffering operations and similar (see "GameOfLife" example.)

Not Yet Implemented

• Test patterns

Getting Started

The easiest way to install the DMD2 library is to use the Arduino IDE's Library Manager:

• Install Arduino IDE 1.6.5 or newer.
• Under the Sketch menu, choose Include Library -> Manage Libraries.
• After the list finishes updating, type "DMD2" in the search field at the top. The DMD2 library should appear.
• Select the latest DMD2 version from the dropdown and click "Install"

Otherwise, you can manually install the Arduino library using the steps described here.

After the library is installed, you will find some example sketches under File -> Examples -> DMD2.

More documentation will be produced before the library reaches final release rather than Beta status. Many of the DMD2 concepts are borrowed from FTOLED library so the FTOLED wiki may be of use.

Feel free to ask questions on the forum if things don't work.

ESP8266 Support

Thanks to @h4rm0n1c there is support for DMD2 on ESP8266 using the Arduino environment. See this comment for the pin connections.

With ESP8266 Arduino core 3, display refresh runs outside the interrupt handler so it can work alongside Wi-Fi. Network traffic can still cause visible shimmer. Older cores use the original timer interrupt code.

ESP32 Support

DMD2 supports SPIDMD on ESP32 with Arduino-ESP32 cores 2 and 3. SoftDMD is not supported on ESP32.

Set up SPI before starting the display if you use custom pins. For example, these connections were used on the ESP32/WROVER test board:

#include <SPI.h>
#include <DMD2.h>

// One panel; output enable, row A, row B, latch
SPIDMD dmd(1, 1, 25, 26, 27, 33);

void setup() {
  // Clock, MISO (unused), MOSI, SS (unused)
  SPI.begin(14, -1, 23, -1);
  dmd.begin();
}

void loop() {
}

Choose pins to suit your board. GPIO16 and GPIO17 are used by PSRAM on WROVER modules. See ESP32 notes for shared SPI, PWM and start/stop behaviour.

Panel Layout

Use dmd.setFlipPanels(true) if alternate rows of panels are mounted upside down to simplify the ribbon cable connections. This is optional; existing layouts are unchanged.

Frames wider than 255 pixels are supported. Make sure the framebuffer, and any temporary frames used when scrolling, fit in your board's RAM.

About the Makefiles

You'll notice the examples directory contains some files named Makefile. You can ignore these if you are using the Arduino IDE.

However, if you want to use other development tools with the DMD library, the Makefiles work with with the arduino-mk package, version 1.3.1. They may need updating to work with newer versions.

Testing

Version 0.0.4 was tested on real ESP8266 and ESP32/WROVER hardware with P10 panels.

• ESP8266 tests used two panels and covered drawing, scrolling, flipped rows and Wi-Fi traffic.
• ESP32 tests used Arduino-ESP32 2.0.17 and 3.3.12 and covered refresh, brightness, Wi-Fi traffic, repeated start/stop and shared SPI use.
• Automated checks cover framebuffer operations and builds for Uno, Countdown, ESP8266 and both ESP32 core versions. See tests to run them.

We haven't tested a physical chain of eight or more panels, a complete multirow wall, or other ESP32 variants. AVR and Due haven't had new hardware tests. The remaining ESP8266 OTA, MQTT and long-running watchdog reports are still open.