A 32x32 LED matrix controlled by a Raspberry Pi and IOIO microcontroller.

Transcription

1 Animated Weather LED Display A 32x32 LED matrix controlled by a Raspberry Pi and IOIO microcontroller. Step 1: Making the connections Connect the USB A-A cable from the Raspberry Pi to the USB connector on the PIXEL IOIO board (3). Set the PIXEL IOIO board toggle swtich (2) to device mode. Connect one end of the ribbon cable into the left IDC connector on the LED matrix and plug the other end into the PIXEL IOIO board (13). Connect one end of the molex power cable into the back of the LED matrix panel and the plug the other end into the PIXEL IOIO board (12). Plug the DC jack wall adapter into the PIXEL IOIO board (4).

2 Step 2: Setting up the Raspberry Pi 1. Download the latest Raspberry Pi SD card image from and install Raspbian. 2. Install the Java Runtime Engine on the Pi sudo apt- get install openjdk- 7 - jre 3. Download the udev rules file from this page, and copy it to your rules directory (one time step). sudo cp 50- ioio.rules /etc/udev/rules.d Then restart udev sudo restart udev

3 or sudo /etc/init.d/udev restart 4. Plug the PIXEL IOIO board into a free USB port on the Raspberry Pi using the USB A-A cable and check if itʼs recognized using this command. Also be sure that the PIXEL IOIO board toggle switch is set to device mode. ls /dev/ioio* You should get back either IOIO0 or IOIO1 meaning the board has been recognized and things are good. Step 5. Run the PIXEL weather app java jar pixelweather.jar zip=<your zip code> Hereʼs the source code for the weather app which is written in Java. Leverage this code and write your own app and please do share with us if you do! Source Code on GitHub for Embedded Weather App Step 3: Install the LED Matrix panel in some cool enclosure Here is a mounting guide and template for the LED panel. Itʼs just now a matter of using your imagination to come up with some cool enclosure. Hereʼs a few ideas:

4 Figure 1 - Old Chart Plotter Case Installation

5 Figure 2 - Antique Mirror Installation

6 Figure 3 - Acrylic Panels Installation

7 Figure 4 Black Frame Installation While this project write-up focuses on the Raspberry Pi, the PIXEL IOIO

8 board also supports apps running on Android, Mac OSX, and Windows. These apps are free and available for download at Not that not all features are available for each OS, details in the table below.

9 Expanding with External Sensors Another thing you can do is leverage the 5 external sensor ports on the PIXEL IOIO board to display something on the LED display based on sensor inputs. At the moment, there are two Android apps written that utilize the external sensors. The interactive animations app uses the proximity sensor for interactive animations that change when someone is near and the alcohol detector app uses the alcohol sensor for a novelty breathalyzer app. Note that the interactive animations and alcohol detector apps are only available on Android and require the Android device to be connected to PIXEL to operate (ie, does not work in stand

10 alone mode). Looking at the LED matrix through diffraction glasses produces a very neat effect. Diffraction glasses split and diffract light into several beams traveling in different directions. This effect will make any light source appear colorful as if it were a rainbow, similar to a kaleidoscope. These glasses have been called firework glasses, prism glasses, rainbow glasses, diffraction glasses, 3d glasses, and rave glasses to name a few. They are best used in places with lots of lights, such as fireworks, nightclubs, and light shows. <iframe width="640" height="360" src="// frameborder="0" allowfullscreen></iframe>

11 The LED matrix contains 1024 LEDs with each LED equivalent to one pixel for a resolution of 32x32. To create your own pixel art, you just need to save your animations in animated gif format or stills in PNG or JPG format, there is no programming required. There are a few nuances when working with LEDs, the main one being low contrast colors don't display well, you'll find do's and don'ts in the Content Guide. While PIXEL's apps will automatically scale images and animated gifs to 32x32, you'll want to keep things as low res as possible as high resolution art work doesn't display well. Both the hardware and software for this project are open source. Under the hood is an LED matrix panel that is driven by a custom IOIO board.

12 IOIO (pronounced "yo-yo") is an open source micro controller board, kind of like Arduino. The main difference between Arduino and IOIO is that with IOIO, you don't need to worry about the microcontroller side of your code. The digital pins, analog pins, and chip level protocols like SPI and I2C are exposed at the application layer via IOIO's Java libraries. As a developer, you only need to focus on your application level code. Traditionally, IOIO development is done in Java although recently some browser based script tools have become available for IOIO. The cross platform nature of Java makes things much easier when porting to additional platforms. It is how for example I was able to release apps for Android, Windows, Mac, and Raspberry Pi. The core code is the same across all the platforms, you just need to handle the UI portion of the code specific to each platform. If you get stuck, you'll find other users hanging out on the IOIO users forum or if it's something PIXEL specific, then use the PIXEL developers forum. The PIXEL IOIO board comes with the firmware pre-installed. If you ever need to upgrade the board firmware, hereʼs how to do that. <iframe width="640" height="360" src="// frameborder="0" allowfullscreen></iframe> PIXEL has two modes: stand alone mode and interactive mode. In stand

13 alone mode, PIXEL will display still images and animations when no longer connected to a device. In this mode, the animation has been saved to the board's local SD card and will continue to run even after the device has been powered off and on. In interactive mode, think of PIXEL as a secondary display that does something based on the logic from your Android or PC app. Your Android device or PC can control PIXEL over Bluetooth or a USB cable connection. To develop your own app for PIXEL, you'll need to be familiar with Android and/or Java programming and will use the PIXEL API. As a side note, I also produced a productized version of this project which was crowd funded on Kickstarter. Taking a hobby project and turning it into a real product was quite the learning experience. In this presentation, I talk about my experiences and lessons learned in doing that. And here s a tour I did with the manufacturer I partnered out of Shenzen, China. Shenzhen is where a good majority s of the world s electronics are manufactured.

14 A special thanks to Ytai Ben-Tsvi, creator of the open source IOIO board, for all his invaluable help on this project. And also to Manju Chintamani who took up the task of modifying the firmware to support the local SD card and stand alone operation. And lastly, Roberto Marquez who was kind enough to develop PIXEL's PC application. Ytai Ben-Tsvi, Al Linke, Manju Chintamani (from left to right) Roberto Marquez (not pictured) Team (from left to right)