This project dealt with timing, frequency, and the phenomenon of persistence of vision. The project required a platform for spinning the display, the display, and the code to run the display.
The base platform is made from sections of 2×4 which provide a sturdy mounting point for the rest of the apparatus. The motor used to spin the LED’s platform is mounted on the wood base. Two ATMega328P boards are used, one for the motor and one for the LEDs. The LEDs are mounted in a breadboard on a separate section of light wood. The light wood and attached components all spin with an external battery allowing for two separate sections of the project.
Successfully getting the persistence of vision words displaying correctly required significant tuning to get the right timing. Another challenge was balancing the spinning section which was solved with weights on the opposite end. The complete product works and demonstrates the fascinating nature of persistence of vision.
An application was also made in the Unity Engine to help generate the necessary characters in a reasonable amount of time.
The final project that our group, DayStar, decided to work on is a LED sign that reads, “Welcome to U of L”. The implementation of a light sensor gives us the ability to change the frequency of the LED lights. With all the LEDs wired together, we are using the Atmel software with an A3BU board to control the abilities.
For our final project, we wanted to incorporate some of the skills we’ve learned in previous labs to create a unique and interactive device. Using pulse width modulation from Lab 4, we incorporated our AVR XMEGA-A3BU XPLAINED with a 4-input number pad, four 10K ohm resistors, a piezo buzzer and jumper wires to create a musical touch pad that plays different songs based on which button is pressed. After getting a general understanding of the keypad schematic, we connected the common connection to VCC on the J2 header of the A3BU. The other 4 buttons were connected to 4 of the ADC pins on the J2 header. We connected the piezo buzzer to the SDA and GND pins on the J1 header. After researching the frequency limits of our piezo buzzer, we were able to assign certain frequency values to specific pitches and program the A3BU to play 4 different songs: Twinkle Twinkle Little Star (button 1), Mary Had a Little Lab (button 2), Jingle Bells (button 3), and Ode to Joy (button 4).
Protect the Brew. After a bad experience with collecting money for a Beer Olympics I came up with the idea for our project, a smart beverage dispenser. One that would limit access to the delicious golden ale inside. Despite my original intentions this project can also be implemented to prevent underage drinking and to keep track of how much people drink. So don’t tell me you had 6 beers when you only drank 4.
The key aspect to this project is the fingerprint scanner. It provides the security we wanted for the project at an affordable price. With two microcontrollers, a Homebrew Draft System, the fingerprint scanner and a solenoid valve the project began. The system is designed so the beverage will only dispense after your fingerprint is verified. We used an Arduino to communicate between the scanner and the A3BU which controlled the other functions. The system will identify who accessed the system and display it on the A3BU LCD. It will also activate one of the LED’s that indicate the status of the fingerprint, red if denied and green if approved. Assuming the approval signal is received by the A3BU it will send a signal that activates a solenoid motor through a transistor circuit. The System will then dispense the beverage for 20 seconds which at 15 psi will fill up a cup.
For our project, we decided to use a powerful electromagnet controlled by a microcontroller. We have a keypad on which user is able to input a code. If the inputted code is correct, then the magnet turns off and allows the user to turn off the magnet. The inspiration for this project came from a similar project, which created a Thor’s Hammer using an electromagnet that turned on and off based on a fingerprint sensor reader. We wanted to do something similar, but put our own spin on it.
Instead of creating an electromagnet from scratch, we decided to take apart an old microwave to convert the transformer into an electromagnet. A transformer has both a primary and secondary coil winding, and so the secondary coil needed to be cut out of the iron core’s housing. Then an angle grinder was used to cut the the weld to cut the top off. Then the primary coil was removed, and placed at the bottom of the iron housing. Masking tape was placed on the inside of the iron housing so that the primary coil was not making contact with the housing.
In order to turn the electromagnet on and off we needed to use an electronic relay with a simple circuit. We used a Grove Relay, which was purchased from FirstBuild. The circuit was simply a battery pack configuration connected to the electromagnet, and the relay was used to open and close the circuit. We also decided to play a simple tone with a speaker when the electromagnet was successfully turned off (i.e. the relay opened). Pictured here is the A3BU, a battery pack with four AA’s, a small speaker, and our electromagnet.
Here is a short video demonstrating the operation of the electromagnet. It shows the user initially entering an incorrect password, and the magnet staying on. Then the user entering the correct password and the magnet turns off. Then after pushing a button on the keypad, the magnet turns back on.
The intent of our final project was to create a keypad lock using a 12-key membrane keyboard and the XMEGA-A3BU board that would trigger a stepper motor to open a mechanical lock. We ran into a problem early on that forced us to change course slightly. The EasyDriver for the stepper motor we were planning on using for our lock did not arrive in time so we decided to go with an alternate driver. This ended poorly for us as the alternate driver caught fire during initial testing, much like our hopes and dreams.
As an alternative, we printed messages to the LCD while also flashing the onboard LEDs to signal that the provided password was correct or incorrect. We also implemented a menu system through which the user can either set or try a password. Passwords can be 10 digits or less, and are hashed upon entry for added security. If the user attempts to try a password before one has been set, an error message is displayed and the user is returned to the main menu.
For our final project our goal was to do something fun that would be entertaining to anyone who used our project. Thus we came up with the idea of the U-box. Our slightly more useful box does everything your typical useless box would do except it also has a cool LCD user interface thanks to the A3BU micro controller.
For those unfamiliar with what a useless box does we can explain. Basically you flip a switch, and then an arm comes out of the box and flips the switch back. This continues until either you give up or the box runs out of power. To this our group added a user interface that shows the attitude of the U-box. The first few times you flip the switch the box is disturbed. Keep flipping and the box will become angry. Finally the box will become so angry he gives up and you win. After this the “game” starts over again.
To accomplish the task of the U-box we needed to use PWM to control the servo motor and LED, input pins to determine if the switch was flipped, and additional software to tell the LCD display what to display to the user. Below is a link to download the video!