Preliminary Design Report

Transcription

1 Preliminary Design Report EEL4924-Electrical Engineering Design 2 University of Florida 25 January 2012 Team Members: Ryan Griffin & Brie Colon Project Abstract: Our project consists of designing an electronic safe. The safe plugs directly into wall power and can be opened with an LCD screen covered with a resistive touch screen. The alphanumeric code is set by the user and can be changed if necessary when the safe door is open. The user may also enter an address. Each time the user enters input to the touch screen, a beep sound will be audible to provide the user with feedback that the code is indeed being received. If the code is wrong, a different sound will be emitted and the error indicator will light up. Once the code is recognized and accepted as the correct code, the safe is set to open. The lock consists of a solenoid, which can be operated directly by a microcontroller and a switch. If the code is entered incorrectly a maximum of three times, a process to notify the user of the possible intrusion is executed. First, a camera, hidden next to the power and error indicator lights on the safe, will capture a picture of the intruder. The picture is then ed to the user over a WiFi network. For further security, the safe will send a log of when the safe was opened in the last month.

2 Page 2/8 Table of Contents Project Features 3 Components... 4 Technical Objectives...6 Division of Labor Projected Timeline....8 List of Tables and Figures 1. System Block Diagram.7 2. Example Process Flow.7 3. Delegation of Tasks Gantt Chart 8

3 Page 3/8 Project Features The purpose of this project is to create a safe that is both secure and easy to use. It will require minimal effort on the user s part to set up. Additionally, the safe will monitor its state with several sensors. If any of these sensors detects a possible intrusion, the user will be alerted through various means. Features include: Robust menu system that will change when various criteria are met (i.e. safe door is open) Photos from an embedded camera and logs detailing when the safe was opened can be ed to the user Backup battery power in case of power failure or safe is moved Power LED (blinks for low battery), error LED (blinks for incorrect code), and door LED give user quick info about the state of the safe Fail-secure lock will not open when supply is unavailable Tones from the embedded speaker will aid the user in entering input and give an audible notification to the user if the pass code is rejected

4 Page 4/8 Technology Selection I. Microcontroller, ATMEGA1284P This AVR was chosen due to its speed, cost and utility. The safe software will depend heavily on interrupts, so a controller with quick response time is needed. Part of the team also has experience with programming AVR processors. II. III. IV. Touch Screen, Donation The user will use a 4 wire resistive touch screen to select options and choose input on the LCD screen. The touch screen should be easy to integrate into the system. A touch screen has generously been supplied by Mr. Stapleton with approximate dimensions of 2 x1.5. Speaker, 8 Ohm Speaker The low impedance speaker allows an increase in the output of the amplifier because of low resistance to current; the speaker can draw more power from the amplifier. A high quality sound is preferred and that is why an 8 ohm speaker was chosen instead of a piezo buzzer. Audio Circuitry, ua741 Op Amplifier & LM386 Op Amplifier This two stage op amp circuit consists of a pre-amplifier and a second low power audio amplifier. V. IR Sensors, IR Emitter and Detector These sensors are used to detect if the door is open or closed. They work at 940 nm wavelength, which is used for general IR purposes. ADC on the microcontroller can be used to easily interface them with the system. VI. Accelerometer, MMA8452Q An accelerometer will measure the dynamic acceleration of the safe in order to detect if the safe is being moved. This will serve as an anti-theft measure. A triple axis breakout accelerometer model has been generously supplied by Mr. Stapleton. It uses 12 bits of accuracy, making it easy to detect subtle changes in position.

5 Page 5/8 VII. VIII. IX. Solenoid Lock, ROB or Donation A solenoid lock is needed to manipulate a physical deadbolt with electronic signals. A 5V model would be optimal to match the power supplies for the rest of the components. A safe, which contains a solenoid lock, has generously been supplied by Mr. Stapleton and may be salvaged. Status LEDs, Various Three LEDs are needed: error, power, and door. These LEDs will have different colors so that the user can easily differentiate them. We will most likely use red, green, and orange with respect to the aforementioned statuses. Camera, LinkSprite JPEG Camera The camera will be used in the alarm process to take a picture of the culprit. The camera is capable of capturing clear color pictures that may help identify a suspect. The camera uses TTL serial interface. A C library has already been supplied by the retailer to ease the learning curve. X. SD Card, SanDisk SDSDB-2048-A11 This card was chosen due to its price. It is a regular SD card that can hold 2GB, more than enough for saving logs, pictures, and user settings. XI. XII. SD Card Adapter Board, SD/MMC Card Adapter To easily interface the SD card with the PCB board, an SD breakout board will be used. It features a 3.3V power regulator capable of supplying external circuits with up to 250mA. This may make it possible for the user to remove the SD card from the safe. Wi-Fi Module, WiFly RN-XV A Wi-Fi module is needed to logs and pictures to the user in the event of an emergency. This module includes a wire antenna and only requires input from a controller. The module uses TTL serial communication, making it easy to use.

6 Page 6/8 Technical Objectives 1. A particular menu will be available to the user based on the state of the safe. When the safe is powered up, it will detect if any previous settings are saved in memory. If settings are found, it will enter the normal routine (see Fig. 1). If no settings are found, the user must complete a first time setup of the safe. The user will be able to enter their password, an address, and choose a wireless network (or opt to set up wireless later). After the initial setup of the safe, the safe will enter the aforementioned process flow. When the door is closed, the only option open for the user will be to input the code. If correct, then door of the safe will open. Once open, options to change the code, address, or select a wireless network will be made available. 2. The system will depend on interrupts from the IR sensors, accelerometer, touch screen, memory, Wi-Fi module, and the backup batteries via ADC (see Fig. 2). The controller will need to be programmed in such a way that it can resolve interrupt calls quickly or temporarily disable global interrupts to prevent interrupts in the middle of other subroutines. 3. Most components must be integrated onto a PCB board that will sit behind the door of the safe. 4. To avoid interference, the IR sensors must have adequate shielding. At the same time, the Wi-Fi module requires an open area to attain a strong connection. It may be possible to hang the wire antenna on the outside of the safe to meet this goal, although this is not the ideal solution.

7 Page 7/8 Flow Charts & Diagrams Figure 1: Example Process Flow Figure 2: System Block Diagram

8 Page 8/8 Delegation of Tasks Table 1 shows how tasks will be divided on this project. Ryan Griffin Brie Colon Preliminary Research 50% 50% Camera, Memory, Wi-Fi design Solenoid, IR sensor, LEDs, Speaker, Accelerometer design LCD, touch screen, power management design 100% 0% 0% 100% 50% 50% Board design 50% 50% Test and Debug 50% 50% Physical Assembly 50% 50% Gantt Chart Table 1: Division of Labor by approximate percentage Figure 3 displays a projected timeline for the project. Figure 3: Project Timeline