The MAX7219 does all the control and refresh work for you in driving either an 8×8 matrix display or 8 x 7-segment displays (usually these also have a dot so its really an 8-segment display) – 64 LEDs total. All you have to do is send it serial commands via the 4-pin SPI interface and it will auto-magically take care of the rest. Wiring is simplified as well, you only need to set the current level for all LEDs with a single resistor instead of 8 and you can also dim the entire display digitally. It’s a thru-hole chip so you can use it in any breadboard, perfboard or other project, although if you’re soldering it in, we suggest using a socket.
MAX7219CNG LED Matrix/Digit Display Driver – MAX7219 - [Link]
Sometimes it’s handy to have a message display when persons enter a specific area. Having the message appear only when someone approaches brings more attention it, and can be useful for holiday displays, directions or warnings. In this project by Jer from Volts and Bytes, an Atmega8 is used to activate a Sure Electronics 0832 LED matrix display when motion is detected by the attached PIR sensor.
The C source and supporting files are available in this zip file.
PIR controlled LED matrix display – [Link]
This instructable is meant to be a more complete explanation than others available online. Notably, this will provide more hardware explanation than is available in the LED Marquee instructable by led555.
GoalsThis instructable presents the concepts involved with shift registers and high side drivers. By illustrating these concepts with an 8×8 LED matrix I hope to provide you with the tools needed to adapt and expand to the size and layout your project calls for.
LED matrix using shift registers – [Link]
Here is a project for beginners to interface a 16-key (4×4) keypad with ATmega32 using 8-pins i.e. one port of the microcontroller. This is useful particularly where we need more keys but don’t want to spend more uC pins for interfacing.
The 4×4 keypad is a standard one available in the market. I’ve used here one from my earlier project. The LED shown in the schematic is just extra, which can be used anyway you like.
4×4 Matrix Key-board Interfacing with ATmega32 – [Link]
This project is pretty cool for a few reasons, and driving a huge LED matrix with a single 8-bit controller is just one of them. The idea was born when I bought 120 LEDs of the wrong type, and decided to do something with them. With that many LEDs, there are only a few things you can do, and a matrix is the natural first-place-winner in the competition of those ideas. One of the LEDs did not work, so a 12×10 matrix was out, so I settled for an 11×10 matrix. This meant I had to drive 110 LEDs. The only controller I had free was a PIC16F688 with 11 pins that can be used for output. After deciding not to use any other chips, charlieplexing was the way to go. The maximum number of LEDs one can charlieplex using N pins is N * (N – 1), so for 11 pins that number is 110. What a coincidence!
One-chip 11×10 LED matrix – [Link]
SAMSA is based on the Wiring board, with an ATmega128 microcontroller, and SAMSA II on the Arduino Mega, with an ATmega1280. Both are pretty similar, tough the ATmega1280 has 8 KB SRAM, twice the ATmega128. For SAMSA II the Arduino IDE was not used. The software was written directly in C++, using some libraries from both Arduino and Wiring.
SAMSA II has also two additional microcontrollers. One is an old Arduino Mini (ATmega168) located in the head, tasked with handling the sensors. The other is an ATmega8 and is integrated in the display. The firmware in the display was replaced with another one, freeing the main microcontroller from handling the display pixel by pixel, storing the frame buffer, etc.
The head’s microcontroller is responsible for sampling, filtering and processing sensor’s data. The data from the Sharp distance sensor and the lateral IR sensors are combined in a single “super smart distance sensor”. This microcontroller also decodes the data coming from the 38 KHz IR receiver, used for the Remote Control.
These two additional microcontrollers further reduce the load on the main microcontroller, allowing for more sophisticated behaviors.
Awesome Hexapod Packs an LED Matrix – [Link]
Last year in one of my classes we were required to make an ‘artefact’ or something that reflects the interests of the class. Most people make posters and the past two quarters that’s what my class did too. Posters however are static, usually boring, and don’t reflect that fact that everyone in the class is an EE major. We decided posters are for noobs and decided to go off the wall a little and make an LED matrix display. Lucky one of my friends John Wathen already had this beautiful 16×24 Green SMD LED matrix that he built back in high school.
16×24 LED Matrix – [Link]
Lampduino is a computer-controlled free-standing floor lamp, comprised of an 8×8 RGB LED matrix. The lamp stands 45″ high and 18″ wide. Light emanates from both sides. It has various display modes, as well as an included editor for creating animations. The lamp is controlled via an application running on a PC host. The display modes include realtime drawing, playback of previously created animations, snow, meteor, plasma, and synchronization with music. With its endless available colors, Lampduino can also be used for color therapy, or as a mood light. When running standalone, without a computer, it plays a soothing plasma simulation.
Lampduino – an 8×8 RGB Matrix Floor Lamp – [Link]
ITead Studio kindly sent me a Colorduino for beta testing. The Colorduino was inspired by SeeedStudio’s Rainbowduino LED Driver Platform. Its form factor is very similar to that of the Rainbowduino, and the layout of the connectors was intentionally designed to mimic the latter. Both boards are based on the ATmega368 MCU, and are Arduino compatible. The principal difference between the platforms is that while the Rainbowduino is based on 3 MBI5168 constant current sink drivers and a M54564 darlington source driver, the Colorduino pairs the M54564 with a single DM163 constant current driver.
Also released an Arduino library that works with both the Colorduino and Iteadʼs Arduino RGB Matrix driver shield.
Tead Studio Colorduino – A Preview – [Link]