Electronic Memory Game

Transcription

1 Electronic Memory Game Hardware Description Jack Sullivan April 30, 2007 Etec 474 Western Washington University

2 Introduction Since the mid 1970 s, game makers have taken the children s game Simon Says into the electronic era in various forms. The first attempt was a memory matching arcade game in The player had to match tones to buttons that lit in a particular sequence. The arcade game was unsuccessful because the tones were harsh and all the buttons were the same color. A different company eventually improved on the design three years later. This unit was portable, with pleasing tones and color. The new memory game became an instant success and it still popular almost thirty years later. For my senior project, I propose to recreate the electronic memory game. Hardware Overview The heart of the circuit consists of the microcontroller, the MC9S12DP512. The total unit will require twenty seven I/O s from the microcontroller. The MC9S12DP512 was chosen because it has more than enough I/O ports for the memory game to utilize. Ten of those I/O s will be used as button inputs. Another eight will be used for an LCD screen that will act as the UI for the players. A PWM port will be used with the unit s audio circuitry to produce sound and the final eight I/O s are connected to the LED display. The references for the I/O are 5V and ground. The crystal used will be 16MHz, which on top of normal operation, will be divided down using software for the PWM. Power to the system comes from a standard household outlet. It will be converted to 12V using a wall wart and 5V using a voltage regulator. Almost every component in the circuitry will use the 5V source. The only parts of the circuit that use the full 12V source are the audio power amplifier and the common pin on the Darlington Pair chip.

3 Power Supply The power supply is a 12V supply taken from a household outlet. A linear voltage regulator (TL780-05) will be used to step this voltage down to 5V. At room temperature, this regulator can dissipate up to 400mA. This should be enough to run the microcontroller at 65mA, the LED driver at its maximum of 130mA and the other required circuitry. The Buttons The circuit s ten buttons are all designed for normally-closed operation. The software will check for a logic zero to determine if a button has been pressed. The circuitry has been designed using 10kΩ resistors and the 5V supply so that only 0.5mA of current are flowing through each section. Eight of the buttons will be used on player controllers. These will be separate boards, each containing four of the buttons. The remaining two buttons will be attached to the main board and will be used to select game options. Audio Amplifier The low power amplifier circuit has been designed as a low-pass circuit with a gain of five. The chip used is the MC34119, and was chosen for is low power properties. The cutoff frequency chosen was 20kHz, due to the limit of human hearing. The input to the amplifier is a PWM created from the microcontroller. The signal will be based on the crystal oscillator and will be divided down with software to a range between 600 and 1000Hz. This makes the cutoff frequency more than enough for the application. Two capacitors are used from pins 2 and 3 to ground to give power supply rejection to the

4 circuit. The output is attached to an 8Ω speaker. Because of standard values, the cutoff frequency will be roughly 19kHz. LED Display The LED display is simple in design. The IC used for this section is an ULN2803A which is a simple circuit made up of eight Darlington Pairs. Each of their inputs will attach to a pin on an I/O port on the microcontroller (Port T). When the input is activated it will allow the LEDs on the output to light up. The LEDs are connected to the output of the chip, with a pull-up resistor and the 12V supply. The resistors are 576 Ω, allowing the maximum current for each LED to be 20mA, with each LED displaying over 1000mcd. In normal operation, there will be two LEDs associated with each color. For worst-case operation, the maximum output current is 130mA. This occurs when all eight LEDs are on with a 100% Duty Cycle. LCD Display The LCD is a 2x16 character display. It will operate in 8-bit mode, using 8 I/O pins (Ports A and K). This was done because of extra I/O on the board, and so that data will only need to be written to it once. This display is part of the UI for the players. It will show them what difficulty they can play at as well as how many players can play. During a game, it will display will briefly display what color is active as the LEDs light up. It will also inform players if they have won or lost the current game.

5 Parts List for the Electronic Memory Game Number Qty Description Designator 1 3 Ceramic Capacitor, 0.1μF C9,C10,C Ceramic Capacitor, 10μF C8,C Electrolytic Capacitor, 10μF C2 7 1 Ceramic Capacitor, 820pF C Ceramic Capacitor, 1μF C3,C Ceramic Capacitor, 22pF C4,C Ceramic Capacitor, 3nF C Ceramic Capacitor, 330pF C Red LED, 5mm D1,D Green LED, 5mm D3,D Blue LED, 5mm D5,D Yellow LED, 5mm D7,D MC34119 Low Power Amplifier IC V Regulator IC LM3915 LED Display Driver IC3-IC MAX6314 Low Voltage Reset IC MHz Crystal X % Resistor, 2kΩ R % Resistor, 4.7 kω R % Resistor, 200 Ω R % Resistor, 10 kω R2-R10,R21,R % Resistor, 576Ω R11-R % Resistor, 680Ω R % Resistor, 18 kω R % Resistor, 3.3 kω R NC Switch SW1-SW Buerklin 8Ω Speaker SP MC9S12PD512 μ-controller U LM162, 2x16 LCD Screen LCD TL Voltage Regulator U ULA2803A LED Driver U MAX6314 Low Voltage Reset U MC34119 Low Power Amplifier U BMD Connection U6