When i first saw this project i thought this could be turned into one of those dance steps learning game. The device consists of a 3×3 matrix of buttons. The system memorates the sequence in which you press the buttons and then plays it for you by lighting a LED under those buttons. You can also program multiple sequences. If you don’t press any button for a longer period of time, 4 seconds i believe, the device goes from recording to playback.
It is quite an interesting memory game, and can be transformed into a larger project. Like in one of those smart houses… in case you get lost this device will show you what path you took. On the other hand the algorithm behind this project can be used in beat generators, sequencers, power distribution sequencers and many others.
The Nove Bit as it was called is using Arduino and a TLC 5940 microcontroller. Source code is available for download as well as some instructions on how to build it.
When POVs first appeared in advertising panels i used to wonder how are the characters diplayed. Seemed like magic. Later on i found out its because of our eyes’ inertia. Where you needed a large number of LEDs to display a message, now you just need to spin a few LEDs. The rotation speed must be fast enough to display at least 10 frames per second, complex graphics may require a higher value between 15 and 30 fps, movies usually have between 24 and 30 fps.
This project will show you with great details how to build such a device. It is not an easy build, it takes a fair amount of tweaking to get it to work but the results can be spectacular. The developers of this project decided on a modular design, putting an emphasis on interactivity. In the end they came up with a very customizable POV that can display images you upload wirelessly and that you can manage in real time.
The microcontroller used is the Atmega644, leds are driven with the MAX6971 IC and Xbee modules provide the wireless serial communication between the POV and the PC from which you upload the image. A GUI written in Java makes this task easy for you.
The LEDs are place on a different PCB than the rest of electronics, this way it can be easily upgraded to a 3D version. The motor part needs some attention because you will have to carefully balance the LED board, you will deal with a lot of vibrations and the speed of rotation can be quite dangerous. Also there will be some tweaking involved when you will build the brushing system to power up the LEDs.
The motor has a separate power supply so that the main PCB won’t pick up noise. A HALL sensor is used to count the rotations and give the position of the LED board. When real time management of the display is not desired, the POV can use the picture stored in its EEPROM.
In order to power it, you will need a 9v power adapter that can deliver at least 1.1A for the electronics boards. Since the motor is powered from different source, you will need to meet your motor’s requirments. The one used in the project had its own 5V/2.5A power supply.
The cost for building this project is a little higher than 50$ and you can further reduce that if you already have some of the needed parts . All schematics and code are found in the project, below you can see the POV in action.
Interesting weekend project for those who still remember the awesome game or just to awake in your kids the knack for electronics here is the Space Invaders Button.
Fairly easy build, having the ATmega16P at the heart controlling an 8×8 bicolor LED matrix which will display animations of the game’s spaceships. Principle of operation is simple, the rows of the matrix are driven by a npn transistor in an emitter follower configuration.
This transistor provides the boost of current needed when two or more leds from the same row are on. The state of the ports driving these transistors is set on “high” logic level. You can now command each LED to light the color you want by setting the assigned port to “0″.
The ATmega16P will draw a small amount of current and can be powered by a 3V cell battery. The PCB is of small dimensions since SMT components are used, it’s even smaller than the LED matrix and thus hides nicely behind it.
It’s an easy project with little chance of failing and offers a nice lesson on how to handle the ports of your microcontroller. If you are doing this just for fun and you don’t care about dimension than the SMT can be avoided so that you can use the controller for other projects.
If you want to impress somebody on Valentine’s day this is a great opportunity, make a DIY led heart, the project comes along with all the source code schematics and even a tutorial to explain the software.
Beside the obvious, lets take a deeper look at the project, the leds are twinkling at random speed and pattern, and yes there are fading not just turning on and off, and there are 20 of them, so how do they do it? No there isn’t a large micro controller with 20 channel pwm, they emulate it in the firmware, and use random numbers to set each leds twinkle. Its worth looking at the solution since in many application, especially with leds you will need to fade more channels than your pwm hardware can handle.
The project also comes with schematic, if you build this kit, place at least a series resistor of 100 Ohm value with PC5 pin, just in case you start to improve the software and forget that the pins can handle only 25mA.
This is an advanced robotics project, the robot arms follows a moving object, anyway that’s the idea. The arms moves a little sloppy, it surely isn’t in the final stage of development, but the author explains what problems encountered. The motion is detected using IR leds and receivers, and subtracting the ambient light from the readings to get the reflected light from the object which is tracked.
If you are interested in motion tracking this is a good place to start, my opinion is that the analog part needs to be reviewed, the IR leds should be mounted inside a tube, otherwise interferes with the reflected light and reduces the sensibility.
