Wireless Motion Sensor

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The idea for the Wireless Motion Sensor projects was to display an alert on the A3BU controller when a distant motion sensor was tripped. In order to achieve this, we used Xbee wireless modules to communicate between two A3BU controllers. The first controller would simply detect when the motion sensor was being tripped. The second A3BU controller would display an alert message on its LCD when the first controller detected movement. There were four distinct parts to this project. The first was to get an A3BU to communicate with the motion sensor. The second was to set up the Xbee modules to allow communication between the two A3BUs. The third was to use the communication from the receiving Xbee in order to make the second A3BU display an alert message. Then the last part was to create a couple of mobile power sources for the two A3BU controllers.

Binary Adder

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This project is a calculator made with two series of LEDs (a yellow series representing input, and a red series representing output); a blue LED for feedback; a potentiometer, used for input; and the A3BU. Interrupts receive input from the pot, and are also tied to a pushbutton switch on the A3BU; the pushbutton is utilized to ‘advance’ the program logic to subsequent operations. It’s a fine example of a project where there’s some hardware, but most of the focus is on software. This addition-only calculator has the user turn a knob to cycle through a series of integers in binary (1-7 in decimal). When the desired number is reached, a push-button is pressed, the A3BU stores the current addend, and the potentiometer knob is again rotated. Once the second addend is reached, the push-button is again pressed, the A3BU sums the two addends, and then outputs the generated value to the red row of LEDs. When the push-button is pressed a third time, the values are cleared from memory, and the program is ready to start over. It’s important for the program to ‘know where it is’ within its flow of execution; otherwise, it executes operations out-of-sequence, leading to unexpected behavior. To this end, a series of flags are used. These flags prevent the program from advancing to its next state until the user indicates (by pressing the push-button) that he or she is ready to advance.

How the Simon Game works

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Here’s the circuit schematics for the Simon game’s input/output. We put four LEDs as output, and each LED was wired as an input as illustrated above. Transistors were used here for two reasons: we might have all four LEDs on at once, and transistors can handle all that current while the A3BU might not. Also, the LEDs from Adafruit ran on 12V, and the A3BU’s 3.3V would not light them. (We discovered that these LEDs have an integrated resistor, that’s why 12V doesn’t blow them up). The transistor can be connected to the ground side, and will switch fully on at 3.3V, completing the circuit through the LED to ground.

The project code is available at our github project repository.

Continue reading How the Simon Game works

“Simon Says” Game

CeladonPost1Image1The goal of this project was to combine transistors, interrupts, and LEDs with the Atmel A3BU microcontroller. It’s a simple push-button Simon Says game. The user watches a developing LED sequence, and then has to repeat it correctly to move onto a more difficult sequence that’s faster with more steps! The project combines the knowledge of embedded systems with circuit and programming skills we have learned throughout the semester. The code determines the sequence of lamps to light, and reads the user input, deciding what to do next. Events are interrupt-driven: user inputs trigger an interrupt handler that makes the next move. The hardware side of the project consists of interfacing the a3bu board with arcade-style push-button lights. The output portion of the circuit must raise the voltage level for the lamps, and the input circuit must provide voltage to the board input when a button is pressed. Ultimately, a working Simon game must have both the hardware and software components working perfectly.

8-Bit Music Player

MalachitePost1Image1This final project was an 8 ­bit music player using the Atmel A3BU Xplained board. A small piezo buzzer played one of four different songs; this project was more heavily tilted toward software than hardware. If you want to learn interrupts, this is the project for you! Interrupts were used to respond to buttons for selecting, playing, and pausing songs. Pulse Width Modulation was used to control the pitch. This project demonstrates good programming practices by creating functions for common tasks. A playNote() function was created which played a note based on given octave and length. The delay_ms() function was used to set the note length. The octave notes of each song were stored in an array, then passed on to the playNote() function, leading to a very compact file. When a song is played, the song title, number, and song status is displayed on the LCD screen.

Smart Nightlight

NightLightThe goal of this project was to create a nightlight-like circuit using the Atmel A3BU microcontroller and light sensor on the A3BUXplained board. The project was a success. The light dims whenever the ambient light from the lights in the room or the sun outside, brightens, and the lights brighten whenever the surrounding light dims or disappears.