Automated Mailbox Design Report
Project & Team Number: Automated Mailbox Dec07-01 Client: Iowa State University Senior Design Group Contact Name: Dr. John Lamont Advisor: Dr. Degang James Chen
Team Members: Tyler Clifton – EE (408) Steve Walker – EE (440)
Mario Limonciello – EE (427) Yee Quan Wong – EE (449)
Date: May 2nd, 2007 DISCLAIMER: This document was developed as a part of the requirements of an electrical and computer engineering course at Iowa State University, Ames, Iowa. This document does not constitute a professional engineering design or a professional land surveying document. Although the information is intended to be accurate, the associated students, faculty, and Iowa State University make no claims, promises, or guarantees about the accuracy, completeness, quality, or adequacy of the information. The user of this document shall ensure that any such use does not violate any laws with regard to professional licensing and certification requirements. This use includes any work resulting from this student-prepared document that is required to be under the responsible charge of a licensed engineer or surveyor. This document is copyrighted by the students who produced this document and the associated faculty advisors. No part may be reproduced without the written permission of the senior design course coordinator.
Table of Contents List of Figures .................................................................................................................... iii List of Tables ..................................................................................................................... iv List of Definitions ............................................................................................................... v List of Definitions ............................................................................................................... v 1. Introductory Materials ................................................................................................... 1 1.1 Executive Summary .................................................................................................. 1 1.2 Acknowledgements................................................................................................... 2 1.3 Problem Statement .................................................................................................... 2 1.3.1 General Problem Statement ............................................................................... 3 1.3.2 General Problem Solution.................................................................................. 3 1.4 Operating Environment............................................................................................. 3 1.5 Intended User(s) and Intended Use(s)....................................................................... 3 1.5.1 Intended User(s)................................................................................................. 3 1.5.2 Intended Use(s) .................................................................................................. 4 1.6 Assumptions and Limitations ................................................................................... 4 1.6.1 Assumptions....................................................................................................... 4 1.6.2 Limitations ......................................................................................................... 5 1.7 Expected End-Product and Other Deliverables ........................................................ 6 2. Approach and Product Design Results .......................................................................... 6 2.1 Approach Used.......................................................................................................... 6 2.1.1 Design Objectives .............................................................................................. 6 2.1.2 Functional Requirements ................................................................................... 8 2.1.3 Design Constraints ............................................................................................. 8 2.1.3.1 Design Constraints ...................................................................................... 8 2.1.3.2 Software Constraints................................................................................... 9 2.1.3.3 Physical and Hardware Constraints ............................................................ 9 2.1.4 Technical Approach Considerations and Results .............................................. 9 2.1.4.1 Sensing Technology Considerations and Results ..................................... 10 2.1.4.2 Transmitting/Receiving Data Technology Considerations....................... 11 2.1.4.3 Processing I/O Considerations.................................................................. 12 2.1.5 Testing Approach Considerations and Results ................................................ 13 2.1.5.1 Microcontrollers........................................................................................ 13 2.1.5.2 Magnetic Switch Test ............................................................................... 16 2.1.5.3 Phototransistor Test .................................................................................. 17 2.1.5.4 Transmitter Test ........................................................................................ 18 2.1.5.5 Entire Test................................................................................................. 20 2.1.6 Recommendations Regarding Project Continuation of Modification.............. 20 2.2 Detailed Design....................................................................................................... 20 2.2.1 Block Diagrams of Design............................................................................... 20 2.2.2 Summary of Material Part Usage..................................................................... 22 2.2.3 Circuit Schematics of Design........................................................................... 25 2.2.4 Microcontroller ................................................................................................ 25 2.2.6 Voltage Regulator ............................................................................................ 27 3. Resources and Schedules ............................................................................................. 27
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3.1 Resource Requirement ............................................................................................ 27 3.1.1 Personnel Effort Requirements ........................................................................ 29 3.1.2 Other Resource Requirements ......................................................................... 32 3.1.3 Financial Requirements ................................................................................... 32 4. Closure Material........................................................................................................... 37 4.1 Project/Team Information....................................................................................... 37 4.2 Closing Summary.................................................................................................... 38 4.3 References............................................................................................................... 38 4.4 Appendices.............................................................................................................. 40
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List of Figures Figure 1: Parallel Port Hood ............................................................................................. 14 Figure 2: Microcontroller Socket...................................................................................... 14 Figure 3: Illuminated LED Test Circuit............................................................................ 14 Figure 4: Programming Socket Layout............................................................................. 15 Figure 5: Microcontroller Testing Circuit......................................................................... 16 Figure 6: Switch Functionality Diagram........................................................................... 17 Figure 7: Phototransistor Test........................................................................................... 18 Figure 8: Transmitter Test ................................................................................................ 19 Figure 9: Receiver Test..................................................................................................... 19 Figure 10: Block Diagram of Sending Signal................................................................... 21 Figure 11: Block Diagram of Receiving Signal................................................................ 22 Figure 12: Microcontroller Pins........................................................................................ 25 Figure 13: Receiver and Transceiver ................................................................................ 26 Figure 14: Voltage Regulator............................................................................................ 27 Figure 15: Deliverables Schedule ..................................................................................... 34 Figure 16: First Half of Schedules.................................................................................... 35 Figure 17: Second Half of Schedules................................................................................ 36 Figure 18: Transmitter Schematic..................................................................................... 40 Figure 19: Receiver Schematic ......................................................................................... 41
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List of Tables Table 1: Components List................................................................................................. 24 Table 2: Estimated Electrical Part Costs........................................................................... 28 Table 3: Updated Estimated Electrical Part Costs ............................................................ 28 Table 4: Estimated Mechanical Part Costs ....................................................................... 28 Table 5: Updated Estimated Mechanical Part Costs......................................................... 29 Table 6: Estimated Labor Costs........................................................................................ 30 Table 7: Updated Estimated Labor Costs ......................................................................... 32 Table 8: Other Resource Requirements ............................................................................ 32 Table 9: Original product cost analysis ............................................................................ 33 Table 10: Revised project cost analysis ............................................................................ 33
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List of Definitions 802.11: Known by the brand Wi-Fi, denotes a set of Wireless LAN/WLAN standards developed by working group 11 of the IEEE LAN/MAN Standards Committee. Access Point: A device that connects wireless communication devices together to form a wireless network. ARM: Advanced RISC Machine. AVR: A series of microcontrollers released by ATMEL. Bluetooth: An industrial specification for wireless personal area networks (PANs). DAPA: Direct AVR Parallel Access. LAN: Local Area Network. LED: Light Emitting Diode. LF: Low Frequency. MF: Medium Frequency. PCB: Printed Circuit Board. Photodetector: Any of various devices for detecting and measuring the intensity of radiant energy through photoelectric action. PIC: Programmable Interrupt Controller. Power PC (PPC): RISC microprocessor architecture originally intended for personal computers, but very popular for embedded and high performance applications. RF: Radio Frequency. Sleep-mode: A state of low power operation. SPI: Serial Peripheral Interface USB: Universal Serial Bus.
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1. Introductory Materials This section will present an executive summary, acknowledgements, problem statement and our general solution. Furthermore, it will discuss the proposed operating environment, intended users and uses for the project, assumptions, and limitations. The expected end-product and other deliverables are then finally discussed last. 1.1 Executive Summary The senior design course notes present the following description of the expected endproduct: “Many older people do not feel comfortable making the journey from their house to their mailbox outside on the street, especially in bad weather. The objective of the automated mailbox system is to alert the person when he/she has received mail. The system detects that something is inserted into the mail box and transmits a signal to the person’s home, indicating that the mailbox door has been opened and something was inserted into the mail box. The system must not interfere in any way with the normal operation of the mailbox or significantly reduce the interior space. The system must be able to withstand normal Iowa winters. It must provide a reasonable battery life with conventional AA or 9-volt batteries. It must indicate when the batteries need to be replaced. It must not provide false signals to adjacent, similar systems. The mailbox owner must be able to insert outgoing mail into the mailbox and not receive a signal of mail present after he/she returns inside.” This design report is part of the Dec07-01 senior design project for EE 491 at Iowa State University. The goal of this project is to design and construct an Automated Mailbox detection system that notifies a user when they have mail. The EE 491 Senior Design course requires students to implement a concrete end product in order to demonstrate a year-long approach to proposing, designing, and constructing a major project. Primarily a hardware project, the Dec07-01 group consists of all electrical engineers. The final end product is expected to be completed in December of 2007. A general solution approach and technical approach will be described in later sections of this design report. The proposed approach to this project consists of individual research on components of the Automated Mailbox system. These components are: microcontrollers, transceivers, LEDs and photodetectors, switches, power regulation, enclosures, and embedded programming. After potential components had been researched, individual parts were chosen. For example, research on microcontrollers led to a list of microcontrollers that would function properly for the design. From that list, the Atmel ATTiny 2313v AVR microcontroller was chosen. This specific microcontroller was chosen due to its low cost and embedded programming capabilities. For the microcontroller, we weighed the pros and cons of each possibility. We had been using this same method for choosing other components in the project. A final parts list has been compiled and included with this
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design report. Also, a parts request was completed to acquire necessary components not obtained from free samples. Upon receiving these parts, we will have begun the integration, implementation, and testing stages of the project. The latter part of the Dec07-01 project will be completed during the fall semester of 2007. The design is geared towards elderly people. The Automated Mailbox allows elderly people to avoid repeated trips to the mailbox by informing them of their mailbox’s status. The Automated Mailbox detection system checks for mail when the door has been opened and closed by using emitted light and photodetectors. If mail is detected, the inhome receiver provides a notification that the mailbox is not empty. The Automated Mailbox is a simple, low cost solution for alerting the user regarding received mail. This system differentiates between outgoing and incoming mail through switch-type logic connected to the mailbox’s flag. This project’s design process was a top-down engineering approach. An overall design of the Automated Mailbox system was created in the form of a block diagram and detailed circuit schematic. These diagrams were created in design software such as Cadence Capture CIS and Microsoft Visio. Using these diagrams as a blueprint, the individual components were easily assembled. Software design for the Atmel ATTiny 2313 AVR microcontroller was written in C. The microcontroller was flashed using Kontrollerlab and a homemade IC programming socket that was connected to a parallel port on a computer. The two remaining major issues are software programming and developing a system for battery status indication. After recently receiving the Atmel ATTiny 2313 AVR microcontroller, we have started writing software for the microcontroller. The process of programming the microcontrollers and transceivers has been slow because not all team members are experienced in embedded programming. Once members learn how to properly utilize SPI with C, programming will have been completed. Team members have been researching a method to check the battery status of the system. Once research is completed, the chosen method will be implemented into the final design. 1.2 Acknowledgements The team acknowledges the senior design instructors, Dr. John W. Lamont, Professor Ralph E. Patterson III, and Dr. Gregory Smith for their instruction throughout this course. Also, the team would like to acknowledge the advisor, Dr. Chen, for his contributions to this project. 1.3 Problem Statement This section will describe the general problem statement and solution. Each of the discussed issues will have to be addressed by the team for a successful project.
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1.3.1 General Problem Statement During harsh seasons, many people, especially the elderly, are frightened about traveling to their mailbox several times a day to check for mail. There are many dangers, especially during the extreme periods of winter and summer. For example, in the winter the driveway may be very icy. It is easy for someone to slip and fall. During the summer, the individual may get heat sickness or heat poisoning. It would be much easier to avoid these conditions if notification were available when there is mail in the mailbox, before making the journey outside. 1.3.2 General Problem Solution This project aims to create a product that will inform the person when mail had arrived in their mailbox. Once something has been inserted into the mailbox, the user is alerted on a receiver located in their home. They can travel outside only when necessary and only need to make a single journey on a day that mail is received. After the person obtains the item from the mailbox, the device resets the receiver in the household, indicating the mailbox is now empty. The device is wireless and requires little installation and maintenance. The battery will last for an extended period of time. 1.4 Operating Environment The transceiver and detectors are both meant to be installed inside of a mailbox. The automated mailbox detection system is durable and resistant to being bumped. The detector system is intended to withstand harsh weather conditions and resistant to rainwater, snow, or dust when the mailbox is opened. Neither the transceiver nor detector can withstand being thrown or dropped, but can slip off a normal table height and still function. The transceiver and detector can withstand temperatures from -10 to 120 °F. The intended operating temperature of the receiver is room temperature, 50 to 80 °F. The receiver's indicators are visible both in a bright and dimly lit room. The receiver is sealed and resistant to light, dust, and water exposure. 1.5 Intended User(s) and Intended Use(s) This section will discuss the target user for the end-product. It will also discuss the product’s designed uses for the target users. 1.5.1 Intended User(s) The target audience for this product is elders, aged sixty-five years old or above. People in this age bracket will find this product the most helpful. Users must be able to read and follow semi-technical instructions for installation of the unit; however, anyone that can fetch mail can utilize this product. Anyone who receives mail will find this product practical and very useful.
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1.5.2 Intended Use(s) The expected use of the Automated Mailbox is to alert the household once the mailbox receives mail. Once mail is removed, the notification will have ceased. The receiver LED does not alert the user when outgoing mail has been placed inside the mailbox when the mailbox flag is raised. The device will however, alert the user when the battery is low on the outside system. The system only activates for a pre-determined time and resets into sleep-mode after completing mail detection and user notification. It cannot be used as a security measure. It does not provide a means for locking or securing the mailbox. This design is strictly used for mail detection and does not provide a way to send, receive, or discard mail. 1.6 Assumptions and Limitations The assumptions and limitations of this project are critical for a success. They are listed in the following sections and are noted throughout the project. 1.6.1 Assumptions Before design: Assumptions An LED indicator is acceptable for notifying the user of mail. The automated mailbox can operate at all hours of the day.
Justifications The design does not cover cases for blind people. When not in use, the device is in a sleep mode. However, when a recognized action occurs the product will be woken up. The user has access to a steady power The home receiver operates from AC source for supplying the rated voltage and power. frequency to the in-home receiver. The mailbox has a door. This design requires a door on the mailbox. The mailbox has a flag. This design requires a flag on the mailbox. The device is used with standard postal This design scope requires a standard service mailbox units. postal service mailbox. The device contains a LED to indicate low The LED is necessary to notify the users. battery on the system. The system activates for a short period of Conserving battery is important to time and deactivates when no activities maximize the efficiency of the product. are performed on the mailbox to conserve battery. The device contains a microcontroller to A processing unit is necessary to manage perform and control all the activities. our electronic system.
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Throughout design: Assumptions The receiver has 2 LEDs, which are green and red. The receiver is used indoors.
Justifications The LEDs are necessary to notify the users on presence of mail and low battery. The design for the receiver is not designed for the outdoors. The mailbox contains a flag with a switch. The switch on the flag enables users to not receive mail notification when putting in outgoing mail. The mailbox contains a door with a The switch on the door activates the whole switch. mail detection system when the mailbox door is closed.
1.6.2 Limitations Assumptions The team is under a time requirement. The project must be completed by December of 2007. The receiver is designed to operate from a standard US 120V, 60Hz household outlet. The device cannot cost over $150 in parts. Labor is not counted in the budget costs. The mailbox detection system must be small enough to fit in a mailbox without a significant loss in space. The battery on the transceiver must last for an extended period of time but eventually needs to be replaced. The receiver must be located near an AC outlet, as it is not battery powered. The transceivers must conform to FCC regulations. The transceivers must weigh less than 1 lb. The transceiver contains a minimum of 4 photodetectors on the bottom of the mailbox. The transceiver contains a minimum of 4 IR LEDs. The transceiver contains only one flag switch.
Justifications This is given by the senior design class requirements. 120V AC power is common and provides an appropriate amount of power for our receiver. This is given by the senior design class requirements, specifications and limitations. The mailbox should be still useable and have enough space for incoming or outgoing mails. The battery is not a constant source of energy. The receiver needs a 120V source; therefore, it must be near an AC outlet. This is a legal issue and the team will abide by it. The design has to be as light as possible. This is the minimum to detect enough IR emission. This is the minimum to provide enough IR emission in the mailbox. There is only one flag on the mailbox.
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The transceiver must have sleep-mode capability. The mailbox detection system contains a magnetic switch on the mailbox door.
The device will need to conserve power while not in use. The switch activates the mail detection system when the door is closed. The device combination operates within 50 The normal range from a house to the feet, while future models may operate in an mailbox is within 50 feet. expanded range.
1.7 Expected End-Product and Other Deliverables The end-product will provide users with notification of mail being inserted into the mailbox. A device will be placed within the mailbox to detect the presence of mail by photodetector and LED identification. This outside unit includes a power source. Once triggered, a signal will be transmitted from the mailbox to an in-house receiver. This inhouse receiver will be powered by a standard AC electrical outlet. Notification is accomplished through LEDs placed on the receiver inside the house. The LEDs will indicate which mode the mailbox is operating in: mail present and/or low battery. The end-product will contain microcontrollers for both of the transceivers to control the activities between the transmitter, receiver, photodetectors, and LED notification. The end-product will also use a flag as an outgoing and incoming mail differentiator switch. This will prevent the device from notifying the household of outgoing mail when the flag is in the upright position. A magnetic switch will be placed between the mailbox and the door of the end-product that activates and deactivates the system. Some possible deliverables will include increased range of transmitted signal from mailbox to home, transmit signal to personal computer for software interface, or a new mailbox with complete installation of the Automated Mailbox. The Automated Mailbox is scheduled for delivery in December 2007.
2. Approach and Product Design Results The following sections will outline the approach used for producing an end-product and the product design results. This section provides a clear overview of the design. 2.1 Approach Used The content below will discuss approaches used during to guarantee a successful design. 2.1.1 Design Objectives This section describes the design objectives for the project. These were developed from the problem statement from the group’s project plan. A detailed description of each objective is also described in the list below.
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•
Alert user when new mail has arrived
•
Transmit a signal to household indicating mail
•
Maintain size of the interior space in mailbox
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Withstand normal Iowa winters
•
Provide reasonable battery life and indicate low battery status
•
Not provide false signals to adjacent systems
•
User can insert mail and not receive signal for new mail
The main objective for the system was to accurately alert the user when new mail had been inserted into their mailbox. This happened when the microcontroller had been activated by the door switch. Next, the microcontroller enabled the IR LEDs and used the photodetectors and comparators to determine if objects were inside the mailbox. If a new object had been detected, a signal was transmitted to the household. The user was notified by a particular LED flashing on the household receiver. An important objective for the system was to maintain as much room as possible inside the mailbox to continue receiving mail and other packages properly. This had been accomplished by minimizing the number of components and choosing small parts. The detection system was located inside a mailbox. This allowed the system to withstand harsh Iowa winters since the only weather element it was subjected to was temperature. The parts we had chosen for the system had wide ranges of temperatures in which they could effectively operate seasonally. The design of the detection system permitted the entire system to be active for short time periods throughout the day. This was controlled by a switch closing the circuit when the door had been open, opening the circuit when the door had been closed. Due to the switch being in the open position, no current flows and battery life will be conserved. The Automated Mailbox detection system operated wirelessly. To avoid interference with other systems, the transceiver will have to send a header in its transmission packet to the receiver. A switch has been placed on the mailbox flag to avoid sending false signals when mail was inserted to be sent out.
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2.1.2 Functional Requirements • Power
The transmission and detection system located within the mailbox is powered by 4 AA batteries. This gives a total of 6 volts to the system. The indoor unit is powered by a standard 120VAC outlet. • User Notification
The user is notified of activity in the mailbox by two viewable LEDs located on the receiver. The LEDs have labels that indicate if mail is present and change in batteries is needed. Whichever LED is flashing is the current state of the system. Each LED is different in color which are green and yellow. • Transmitting and Receiving
Transmission is set up for 50 feet. The transmission does not interfere with other systems operating at the same frequency, such as other similar mailbox units. • Mail Detection
The mail detection system does not report false alerts on differently sized items in the mailbox. Mail detection occurs by a series of IR LEDs and IR photodetectors. 2.1.3 Design Constraints This project has key constraints that have needed to be addressed. These include design constraints, software constraints, as well as physical operating limitations. 2.1.3.1 General Constraints • Weight
The Automated Mailbox detector system must be light enough to be mounted on a mailbox without putting excessive stress on the mailbox. The switches must be light enough that the door and flag could hold them without breaking. The other mailbox mounted components must be light enough that the walls are not stressed to the point of cracking or breaking. • Maximum Size
The system is not large or bulky. It is placed inside a mailbox; therefore, it allocates space, but still allows mail and packages to be placed inside without interference. This corresponds to the goal of making the size of the system small. The final size is not absolute since the prototype is not built.
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• Cost
The cost of building the system does not exceed $150. It is important to choose parts carefully keeping in mind that there is a limited budget. Requesting free samples from various companies will help keep the overall budget low. 2.1.3.2 Software Constraints • Microcontroller and Transceiver Interaction
The microcontroller and transmitter, as well as the receiver, use SPI as a standard protocol for communications. Therefore, programming for these devices in C is done in SPI format. C is the best choice for our team because team members are familiar with it. 2.1.3.3 Physical and Hardware Constraints • Power
The outdoor portion of the system operates with AA batteries. The system indicates when the power supply is low and the batteries need to be replaced. • Operating Environment
The Automated Mailbox is intended for outdoor use. It withstands normal Iowa winters, as well as all other seasons. The device requires little or no outside light to be permitted in the mailbox. This is due to the LEDs and light sensitive photodetectors being located within the mailbox. The switch located on the flag is waterproof and securely attached. 2.1.4 Technical Approach Considerations and Results In the design and implementation of the Automated Mailbox detection system, there were many types of technology considered. The design of the system led to many questions. The team faced questions involving: •
How the mailbox will sense when new mail is received?
•
How the information will be transmitted?
•
What type of processing will be used?
The following sections discuss the different technology considerations the team made for these stages of design. There are many possible solutions to the problem; however, the team believes it has chosen the best overall solution.
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2.1.4.1 Sensing Technology Considerations and Results The main purpose of the Automated Mailbox is to correctly sense when mail was inserted into the mailbox. The following sensing technologies have been explored for cost, effectiveness, and feasibility: •
Laser Sensing
•
Weight Detection
•
Motion Detection
•
IR/Photodiodes
Laser sensing detects mail when its narrow beams had been broken. The beams could be placed in strategic locations, and would break when mail had been placed into the mailbox. Once a beam is broken, the microcontroller would send a signal to the transmitter which would then send a signal to the receiver that mail has been inserted into the mailbox. However, constant movement of the mailbox (i.e.: wind) could misalign the beams, decreasing the accuracy of the detection system. Team member are very foreign with the use of lasers. Due to this unfamiliarity of lasers, they are not to be utilized. Another method of sensing the mail is weight detection. This method senses mail by a change in weight in the mailbox. A major difficulty with using this method is the detection of low weight mail. This would require precise weight measurements, which would be difficult to produce. External elements could also affect the weight sensors on the mailbox, causing a decrease in an accurate detection. Temperature, moisture and dust would also affect the accuracy of the weight detection. Therefore, this method is not the most accurate or practical way to detect mail. Motion detectors are also considered for detecting the presence of mail. The movement of something in the box triggers the detector, which causes the microcontroller to send a signal for mail notification. This technology must be very sensitive to accurately detect mail. Due to the high sensitivity, any slight movement in the mailbox would activate the detector. Also, if someone opens the mailbox and does not insert anything, a false signal can be triggered. Due to the many causes of false signals, this method is not employed by the system. The final method considered for sensing mail is the use of IR/Photodiodes. This detection method works by photodiodes detecting infrared beams from LEDs. The LEDs are located on the interior top and sides of the mailbox, while the photodiodes are on the floor of the mailbox. When mail is placed in the box, the mail blocks the photodiodes from sensing the LED beams. This sends a signal that mail had been inserted into the mailbox. This solution is better than lasers because the LEDs have a wider angle, which cover more area within the mailbox, and do not require precision alignment. LEDs are not sensitive to the weather causing sudden movements, as weight and motion detectors
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are. Therefore, this detection method is more applicable. IR/Photodiodes are used in the final design for the Automated Mailbox System. This type of sensing approach is low cost, as well as very effective. The pros far outweigh the cons for IR/Photodiodes. 2.1.4.2 Transmitting/Receiving Data Technology Considerations The most important operation for the Automated Mailbox is to transmit and receive the data between the mailbox and in-home receiver. Accurately sending this data could be accomplished by the following methods: •
Bluetooth
•
802.11 a/b/g
•
RF transmission
Bluetooth technology is a popular wireless burst transmission system. It provides a way to transmit data from the mailbox and receive it in the house. This technology is appealing because it has very low power consumption, allowing the system to have a longer battery life. However, Bluetooth technology is too expensive for the Automatic Mailbox Teams’ budget. Bluetooth is an ideal short range wireless communicator at 10ft. For future considerations, however, Bluetooth would not be able to support the system at 50ft. As the distance between the mailbox and household grows, the effectiveness of Bluetooth decreases. Bluetooth technology is not implemented in the design due to high cost and future ineffectiveness. 802.11 a/b/g is a wireless LAN system. 802.11 specifies an over-the-air interface between two wireless clients. In the Automated Mailbox case, the two wireless clients are the mailbox and the receiver in the household. This type of setup works for the Automated Mailbox detector; however, due to the high cost of this setup, it is not ideal. RF Transmission uses radio waves to transmit the signal from the transmitter to the receiver. This type of setup is a less expensive. RF transmission requires a specific frequency that does not interfere with other existing wireless networks in the area. RF Transmission is implemented into the final Automated Mailbox design. This type of setup has many pros and few cons.
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2.1.4.3 Processing I/O Considerations When mail has been placed in the box, the transmitter needs to receive a signal from some form of processing unit. This unit tells the transmitter and receiver what and when to send or read data. The data could be processed through the following technologies: • •
Microprocessor Microcontroller manufacturers PIC Atmel Intel Hitachi
A microprocessor is a programmable digital unit that encompasses the behaviors of a central processing unit. If a microprocessor is to be used, many different external components would have been required. For example, memory for the microprocessor is needed to store information. Due to the external devices, the size of the microprocessor would increase which is not ideal. A microcontroller is another type of microprocessor containing other necessary components on the same chip, making it low cost and effective. Since this type of processing requires no external components, it is ideal for our product design. While most of the microcontrollers would work for our design, the Atmel microcontroller provides the optimum functionality for the end-product. The Atmel ATTiny 2313 AVR microcontroller is used in the final design because is it low cost and supports the computer language C. It was chosen over PICs because a newer version of a PIC is needed to support C. This newer version is more expensive then the Atmel ATTiny 2313 AVR microcontroller. The Atmel version of the microcontroller is chosen over Intel and Hitachi primarily because Atmel is less feature filled then the other microcontrollers. The Intel and Hitachi have too many excess features that are not needed for the Automated Mailbox. Obtaining a chip with too much functionality is a waste of money.
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2.1.5 Testing Approach Considerations and Results Throughout the design process, several components had not yet been finalized. The team ordered samples of multiple alternatives that could be used until a finalized list was developed. Low cost parts were purchased out of pocket, while high cost parts were purchased through the university. The higher cost parts were heavily researched prior to selection. The team verified functionality of each component with the preceding tests. 2.1.5.1 Microcontrollers We chose a microcontroller that we knew was compatible with the microcontroller programmer available in the senior design lab. Unfortunately, the software on the computers was not updated to a release to support our microcontroller. The senior design coordinators acknowledged that the machines had older software, and were “going to look into installing a new version”. We were supposed to receive an email when this happened. Since we never received the said email and the software was not upgraded, we had to explore options involving building our own flashing device and obtaining our own flashing software. The microcontrollers required a build environment and a microcontroller programming socket be made and set up with a computer. The software environment can be easily varied to work on other Linux distributions as well as with other versions of the AVR libraries/supporting applications. The developing computer had Ubuntu 7.04 installed, which contained compatible versions immediately available in the software repositories. The supporting applications have the ability to use a variety of different programming sockets including both commercial and homemade projects. The team opted to manufacture a homemade programming socket using parts from Radio Shack and an online guide. This guide refers to the programming socket as a DAPA (Direct AVR Parallel Access) that uses a SPI interface.
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Figure 1: Parallel Port Hood
Figure 2: Microcontroller Socket
Figure 1: Parallel Port Hood
Figure 2: Microcontroller Socket
As indicated in the above pictures, the socket has been soldered. Microcontrollers were then tested and verified for functionality with a test application. This application simply flashes an LED on and off when the microcontroller applies power.
Figure 3: Illuminated LED Test Circuit
Figure 3 shows the illuminated LED that is connected to a microcontroller. The LED illuminates due to the code below: /* Blinker Demo */ /* Include useful pre-defined functions */ #include
make programs easier to read
// Defines pins, ports, etc to
#define F_CPU 100000UL for delay.h
// Sets up the default speed
#include int main(){ DDRD = _BV(PD4);
/* enable output on
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port D, pin 4 */ while(1){ PORTD = _BV(PD4); _delay_ms(1000); PORTD &= ~_BV(PD4); _delay_ms(1000); } return(0); }
The microcontroller flashes in the socket using an SPI interface. The microcontroller has been hooked up as above in Figure 4 for programming purposes:
Figure 4: Programming Socket Layout
After the microcontroller was properly programmed, a LED had been attached with a resistor in series and power applied.
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Figure 5: Microcontroller Testing Circuit
Software Used: Ubuntu Linux 7.04, "Feisty Fawn" avr-libc 1.4.5-2 gcc-avr 4.1.0-1 avrdude 5.2-2 uisp 20050207-3 kontrollerlab 0.7.1-0ubuntu1
2.1.5.2 Magnetic Switch Test The switches appear as an open circuit when two magnetic contacts are placed together. When the contacts are placed together, no current is flowing. When the two contacts have been pulled apart, little power is dissipated. The switches had been tested for basic switch functionality. To test the basic switch functionality, a multimeter had been used in continuity mode. The switch had been initially connected with both contacts touching. The team verified that there is no continuity in the setup. The contacts were then pulled apart continuity was verified.
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Figure 6: Switch Functionality Diagram
Figure 6 shows that the switch is open when the magnetic contacts are together. The switch then closes allowing current to flow when the magnetic contacts are pulled apart. 2.1.5.3 Phototransistor Test The Phototransistor test involved testing many components related to detecting IR within the mailbox. First, the IR diodes had been tested in the same test configuration as the microcontroller circuit. A mobile phone camera had been used to verify that the circuit was emitting IR. After verifying that the IR diodes worked, the phototransistor/comparator circuit had been assembled. This circuit supplied a digital output of high when IR was detected, and low otherwise. To test the circuit, a short microcontroller program had been written. //Photodiode test code //Basic code for testing photodiode functionality //see "Photodiode Test Diagram.png" for hookup information //Mario Limonciello, March 2007 #include // Defines pins, ports, etc to make programs //easier to read #define F_CPU 100000UL // Sets up the default speed for delay.h #include int main() { //enable pin 7 (PD3) and pin 9 (PD5) to be output pins DDRD = _BV(PD3) | _BV(PD5); //drive pin 9 (PD5) high all the time since its driving an LED PORTD = _BV(PD5); while (1)
- 17 -
{ //if pin 8 (PD4) is high, then turn on pin 7 (PD3) if (PIND & _BV(PD4) ) PORTD |= _BV(PD3); else PORTD &= ~_BV(PD3); } return 0; }
This program enables an IR LED all the time and listens for an input on one of the pins. When input is detected on this pin, an ordinary LED is turned on. Before attaching the full phototransistor circuit, the team used the Magnetic Switch from the earlier test to verify that the input pin had been working as intended.
Figure 7: Phototransistor Test
After verifying functionality of all other components, the photodetector comparator circuit was tested with these other components for functionality. 2.1.5.4 Transmitter Test The transmitter test required the use of two transmitters, as well as two microcontrollers. The transmitters were only testable with the microcontroller. Code needed to be written to configure both transmitters when the microcontroller powers up, as well as set them up for transmitting data. Code from the phototransistor/comparator test was used to develop code for determining when to transmit a bit.
- 18 -
After coding and flashing both devices, the following circuit had been used for testing purposes:
Figure 8: Transmitter Test
Figure 9: Receiver Test
A bit had been sent by setting the input pin high. The result had been displayed on the LED connected to the receiver.
- 19 -
2.1.5.5 Entire Test Once each component had been verified functionally, the team proceeded with assembling the circuit. Small portions of code from each part were used in contribution to the final code. The switches had been used in the test circuit to stimulate the interrupts seen by the mailbox door and flag. Since all the components have been verified functionally, if the circuit does not work properly this means the code being used has an issue. 2.1.6 Recommendations Regarding Project Continuation of Modification At this time a decision had to be made by individuals invested in this project as to the proper course of action. There had been three options available: (1) continue the project as originally envisioned, (2) alter the direction of the project, or (3) abandon the project. At this time, the Automated Mailbox detection system Dec07-01 project is to be continued as scheduled. The final decision will have to be made by the faculty advisor and clients at the end of first term. The Dec07-01 project team feels that good progress is continuing to be shown. All deadlines have been met, adequate research has been performed, and vast amounts of knowledge concerning components related to the detection system have been acquired. The team has been on schedule, knowledgeable, and competent enough to complete the project as envisioned. 2.2 Detailed Design The detailed design will discuss all parts used for the end product in detail, while summarizing their costs in a table. 2.2.1 Block Diagrams of Design The following block diagrams represent high level illustrations of the sending and receiving aspects of the Automated Mailbox.
- 20 -
Sending Signal LED Voltage Comparator
Magnetic Switch
Photodetector Microcontroller
Transceiver
Sending Signal
Figure 10: Block Diagram of Sending Signal
Figure 10 illustrates a block diagram for the sending portion of the system. The switch is an input to the microcontroller. The microcontroller then turns on the LEDs. The voltage comparator compares a previous set voltage level to the current level in the photodetectors. If this level is different, the microcontroller outputs this data into the transceiver, which finally sends a signal to the receiver. - 21 -
Figure 11: Block Diagram of Receiving Signal
Figure 11 demonstrates the receiving portion of the system. The transceiver obtains the signal and outputs it into an input of the microcontroller. The microcontroller then flashes the corresponding LED to notify the user that either mail is present or a change in batteries is needed. 2.2.2 Summary of Material Part Usage This section provides an overview of parts used in the design. • Microcontroller
The microcontroller is used to control all other components in the design. The team’s microcontroller has an 8-bit architecture with 2 Kbytes of in-system programmable Flash memory. There are also 128 Bytes of Data EPPROM and 128 Bytes of SRAM. • Magnetic Switch
The magnetic switches comprise of two sections that function like the inverse of an ordinary switch. When the two pieces of the switch are touching, the circuit appears to - 22 -
be an open circuit. When the two pieces are separated, the circuit appears closed and current flows. It does not dissipate power unless the mailbox door is open. When the door is open, a minimal amount of power is dissipated. This dissipation is not enough to affect the battery significantly. It conserves the battery while not in use. • LED
LEDs are used to provide notification to a user regarding their mailbox’s status. These LEDs are powered by the microcontroller in the in-home receiver unit. The microcontroller will determine when the usage of an LED is necessary. • IR LED
Infrared LEDs are used for the detection process. They are powered by the microcontroller within the mailbox. These LEDs are governed by the microcontroller in the detection system, thus determining when their usage is necessary. The IR LEDs are used in the mail detection system and are placed on the top and sides of the mailbox. • Photodetector
The photodetector will detect infrared light 935 nm emitted by the IR LED. The photodetectors are used in the mail detection system. These photodetectors were placed on the bottom of the mailbox. Upon presence of mail, one or more photodetectors are covered, therefore they received less light. A signal was sent to the microcontroller alerting that mail is present. • Voltage Regulator
The voltage regulator regulates the voltage from the supply, such that the voltage seen by the devices is unaffected by the degradation of the batteries. The voltage regulator operates by stepping a 6 V (4-AA) input down to a 3.3 V output. • Comparator
The comparator interprets voltages caused by current from the photodetector over a resistor. It compares two voltages at the + and – terminal. The larger voltage will cause an output of its corresponding VDD or VSS. It will convert these values to a binary zero or one as the VDD will consider one and VSS is zero. • Transceiver
The transceivers are responsible for wireless communication between the mailbox and household. All transmissions occur on a range of channels operating at 2.4 GHz. These transceivers utilize registers when transmitting data.
- 23 -
Image
Part Name
Manufacturer Part Number
Cost
Microcontroller
Atmel
ATTiny 2313 AVR
Free Sample
Voltage Regulator
Texas Instruments
LM 317
Free Sample
Mailbox
Lowes
MB533B-04
$7.48
Infrared LED
OPTEK
OP165
Free Sample
Magnetic Switch
GE
1086-N
Free Sample
Photodetector
OPTEK
OP505
Free Sample
Batteries
Duracell
AA
$4.00
Transceiver
MiRF v2
nRF24L01
$29.95
Resistors
Digikey
Various
Free Sample
Table 1: Components List
- 24 -
2.2.3 Circuit Schematics of Design See appendices for the schematics used for the receiver and transmitter. 2.2.4 Microcontroller The Atmel ATTiny 2313v AVR is a basic 8-bit microcontroller in a 20 pin Plastic Dual Inline Package. Eighteen pins are open for general input/output pins and can be customized for multiple purposes. It has 2 Kbytes of in-system self programmable flash, 128 Bytes of in-system programmable EEPROM, and 128 Bytes internal SRAM. The device is highly flexible when choosing a power supply voltage. It can operate at voltages ranging from 1.8 - 5.5 V. Atmel AVR series microcontrollers support programming in either assembly or embedded C programming languages. The device is also capable of communicating in SPI format with other hardware devices.
Figure 12: Microcontroller Pins
The end-product contains two microcontrollers used in its design. This section describes the connections between devices attached to the microcontroller. The team will make reference to the pins directly on the microcontroller (Figure 12). One microcontroller, in the mailbox, is used for the photodetection system. An RF transceiver is attached to the pins defined for SPI interface on Port B (pins 14-19). The transceiver uses the same nomenclature as the microcontroller for its SPI pins. According to SPI specification, the microcontroller is a master devices with pins 16, 17, and 19 defined as output pins. The other pins are defined as slave device input pins. The switches are connected to pins 6 and 7. These pins are defined as inputs to the
- 25 -
microcontroller. The IR photodection system is connected to pins 2 and 3. The microcontroller determines when to enable different outputs based on switch interrupts. The second microcontroller is used solely for feedback to the user on outside activity. The RF transceiver is attached to the pins defined for SPI interface on Port B, pins 1419. Even though this transceiver is primarily in receiving mode, the microcontroller acts as the master device. Two pins are used for LEDs to indicate the system’s outside battery and mailbox statuses. These LEDs are attached to pins 7 and 8. The two pins are assigned as output pins. 2.2.5 Transceivers
Figure 13: Receiver and Transceiver
The transceiver used is the MiRF v2, which is based upon the Nordic nRF24L01, Single Chip 2.4 GHz Transceiver. This acts as the team’s Automated Mailbox transmission and reception system. The objective of the transmitter is to send a signal produced by the microcontroller once verification of mail is made from the photodetectors. The transceiver sends the signal to the receiver located within the household. The transceivers use an SPI interface for programming and communication, which is compatible with the microcontrollers. The SPI specification allows for two or more devices on a bus to communicate, designating one as a master with the rest being slave devices. The microcontroller is the master device, allowing it to control the timing, clocking, and functionality of the transceiver. The MiRF v2 simplifies many of the complicated steps with regard to clocking data, adding an antenna, and setting up additional features supported by the Nordic nrF24L01. The only pins available to the Nordic are the standard SPI pins and power. Upon initial power, the microcontroller sends a set of configuration data to the transceiver via SPI. The transceiver powers up after processing the configuration data. Once the transceiver is ready, it sends a signal to the microcontroller indicating that it can begin processing data. From this point, the microcontroller controls all data transfers to and from the transceiver.
- 26 -
2.2.6 Voltage Regulator
Figure 14: Voltage Regulator
The Texas Instruments LM317, voltage regulator, acts as the voltage step down system. The voltage regulator takes the voltage from 4 series connected batteries (6 V) and steps it down to 3.3 V. This step is necessary to provide the appropriate amount of voltage to the microcontroller and other devices. The voltage regulator works by adjusting the values of multiple resistors and capacitors attached to external pins. The chosen output voltage is determined by the following formula: ⎛ R ⎞ VOUT = 1.25 × ⎜1 + 2 ⎟ + Iadj ( R2 ) R1 ⎠ ⎝
3. Resources and Schedules This segment will include the estimated prices for parts, total hours spent working on the project, and the schedule of events the team follows. Tables are presented in the following pages. 3.1 Resource Requirement A basic financial estimate based on all of the electronics necessary is assembled in tables 2 and 3. The spending limit is $150 dollars on the project, but the team does not anticipate coming close to this value. The current estimates are only for the electronics for the receiver and transceiver. Until electrical performance is verified, mechanical sizing will be unknown.
- 27 -
Part
Cost per item
Quantity
Total Cost
Battery (9V)
$4.00
1
$4.00
Microcontroller
$3.00
2
$6.00
RF Transceiver
$6.00
2
$12.00
Photodiode
$0.50
6
$3.00
IR LED
$0.40
1
$0.40
Magnetic Switch
$3.00
2
$6.00
$8
2
$16
PCB Total
$47.40 Table 2: Estimated Electrical Part Costs
Part
Cost per item
Quantity
Total Cost (with Free Parts)
Total Cost (without Free Parts)
Battery (9V)
$4.00
1
$4.00
$4.00
Microcontroller
$1.79
2
$0
$3.58
RF Transceiver
$29.95
2
$59.90
$59.90
Photodetector
$0.25
9
$0
$2.25
IR LED
$0.30
3
$0
$0.90
Magnetic Switch
$3.50
2
$0
$7.00
20-Pin Retention Socket
$0.69
1
$0.69
$0.69
25 Pin D-Sub Connector Hood
$1.79
1
$1.79
$1.79
25 Pin D-Sub Connector
$1.89
1
$1.89
$1.89
PCB
$1.79
1
$1.79
$1.79
$70.06
$83.79
Total
Table 3: Updated Estimated Electrical Part Costs Part Screws
Cost per item
Quantity
Total Cost
Provided
20
$0
$20 $8
1 1
$20 $8
Transmitter housing
$8
1
$8
Plexiglas
$6
1
$6
Power Cord
$5
1
$5
Mailbox Receiver housing
Total
$47 Table 4: Estimated Mechanical Part Costs
- 28 -
Part
Cost per item
Screws
Quantity
Total Cost
Provided
20
$0
$7.48 $8
1 1
$7.48 $8
Transmitter housing
$8
1
$8
Plexiglas
$6
1
$6
Power Cord
$5
1
$5
Mailbox Receiver housing
Total
$34.80 Table 5: Updated Estimated Mechanical Part Costs
3.1.1 Personnel Effort Requirements In order to successfully complete this project on time, each team member has pledged to devote the following times for each task. By looking at each task specifically, the team can successfully plan on how much time it takes and create a schedule. Mario
Tyler
Steve
Renee
Total
Task 1: Problem Definition 1a: Problem Definition Completion 1b: End User(s) & End-Use(s) Identification 1c: Constraint Identification
3
3
3
3
.25
.25
.25
.25
12 1
5
5
5
5
20
8.25
8.25
8.25
8.25
33
2a: Identification of Possible Technologies
5
5
5
5
2b: Identification of Selection Criteria
3
3
3
3
12
2c: Technology Research
8
8
6
4
26
2d: Technology Selection
2.5
2.5
2.5
2.5
10
18.5
18.5
16.5
15.5
69
5
5
5
5
Subtotal Task 2: Technology Considerations & Selection
Subtotal
20
Task 3: End Product Design 3a: Identification of Design Requirements
20
3b: Design Process
45
45
45
45
180
3c: Documentation of Design
15
15
15
15
60
Subtotal
65
65
65
65
260
10
10
10
10
Task 4: End-Product Prototype Implementation 4a: Identification of Prototype Limitations & Substitutions
40
- 29 -
4b: Implementation of Prototype End Product
25
25
25
25
Subtotal
35
35
35
35
140
8
8
8
8
32
5b: Test Development
12
12
12
12
48
5c: Test Execution
22
22
22
22
88
5d: Test Evaluation
5
5
5
5
20
5e: Documentation of Testing
15
15
15
15
60
Subtotal
62
62
62
62
248
6a: Development of End-User Documentation
20
20
20
20
6b: Development of Maintenance & Support Documentation
20
Subtotal
40
40
40
40
160
10
10
10
10
40
7b: Faculty Advisor(s) Demonstration
1
1
1
1
4
7c: Client Demonstration
1
1
1
1
4
7d: Industrial Review Panel Demonstration
1
1
1
1
100
Task 5: End-Product Testing 5a: Test Planning
Task 6: End Product Documentation 80 20
20
20 80
Task 7: End-Product Demonstration 7a: Demonstration Planning
4
Subtotal
13
13
13
13
52
16
16
16
16
64
8b: Project Poster Development
5
5
5
5
20
8c: End-Product Design Report Development
20
20
20
20
8d: Project Final Report Development
20
20
20
20
80
8e: Weekly Email Reporting
30
30
30
30
120
Subtotal
91
91
91
91
364
332.75 332.75 330.75 Table 6: Estimated Labor Costs
329.75
1326
Task 8: Project Reporting 8a: Project Plan Development
Total
80
- 30 -
Mario
Tyler
Steve
Renee
Total
Task 1: Problem Definition 1a: Problem Definition Completion 1b: End User(s) & End-Use(s) Identification 1c: Constraint Identification
3
3
3
3
.25
.25
.25
.25
12 1
4
4
4
4
16
7.25
7.25
7.25
7.25
29
2a: Identification of Possible Technologies
5
5
5
5
2b: Identification of Selection Criteria
3
3
3
3
12
2c: Technology Research
8
8
6
4
26
2d: Technology Selection
2.5
2.5
2.5
2.5
10
18.5
18.5
16.5
15.5
69
5
5
5
5
Subtotal Task 2: Technology Considerations & Selection
Subtotal
20
Task 3: End Product Design 3a: Identification of Design Requirements
20
3b: Design Process
45
45
45
45
180
3c: Documentation of Design
15
15
15
15
60
Subtotal
65
65
65
65
260
4a: Identification of Prototype Limitations & Substitutions
10
10
10
10
4b: Implementation of Prototype End Product
25
Subtotal
35
35
35
35
140
8
8
8
8
32
5b: Test Development
12
12
12
12
48
5c: Test Execution
22
22
22
22
88
5d: Test Evaluation
5
5
5
5
20
5e: Documentation of Testing
15
15
15
15
60
Subtotal
62
62
62
62
248
6a: Development of End-User Documentation
20
20
20
20
6b: Development of Maintenance & Support Documentation
20
Subtotal
40
Task 4: End-Product Prototype Implementation 40 25
25
25 100
Task 5: End-Product Testing 5a: Test Planning
Task 6: End Product Documentation 80 20
20
20 80
40
40
40
160
- 31 -
Task 7: End-Product Demonstration 7a: Demonstration Planning
10
10
10
10
40
7b: Faculty Advisor(s) Demonstration
1
1
1
1
4
7c: Client Demonstration
1
1
1
1
4
7d: Industrial Review Panel Demonstration
1
1
1
1 4
Subtotal
13
13
13
13
52
16
16
16
16
64
8b: Project Poster Development
5
5
5
5
20
8c: End-Product Design Report Development
20
20
20
20
8d: Project Final Report Development
20
20
20
20
80
8e: Weekly Email Reporting
10
10
5
5
30
Subtotal
71
71
66
66
274
311.75 311.75 304.75 Table 7: Updated Estimated Labor Costs
303.75
1232
Task 8: Project Reporting 8a: Project Plan Development
Total
80
3.1.2 Other Resource Requirements There were other miscellaneous requirements that were not included in the project budget. These resources are detailed in Table 3 below. Item
Cost
Printing of project plan Printing of design report Miscellaneous
$4.00
Total
$15.00
$5.00 $6.00
Table 8: Other Resource Requirements
3.1.3 Financial Requirements This section will include financial costs associated with this project. Besides the material cost, the cost due to labor is also calculated based on hourly rate of $10.00. The information on Table 9 lists the closest possible value based on market research.
- 32 -
Item Part & Material 1. Battery 2. Microcontroller (2x) 3. Transceiver (2x) 4. Photodiode (6x) 5. LED 6. Magnetic Switch (2x) 7. PCB (2x) Subtotal Other costs (from Table 8)
W/O labor
With Labor
$4.00 $12.00 $12.00 $3.00 $0.40 $6.00 $16.00
$4.00 $12.00 $12.00 $3.00 $0.40 $6.00 $16.00
$53.40 $ 15.00
$53.40 $ 15.00
Labor at $ 10.00/hr Mario Tyler Steve Renee
$ 3327.50 $ 3327.50 $ 3307.50 $ 3297.50
Subtotal Total Project Cost
$ 68.40 $ 68.40 Table 9: Original Product Cost Analysis
Item Part & Material 1. Battery 2. Microcontroller (2x) 3. Transceiver (2x) 4. Photodetector (6x) 5. LED 6. Magnetic Switch (2x) 7. 20-Pin Retention Socket 8. 25 Pin D-Sub Connector Hood 9. 25 Pin D-Sub Connector 10. PCB Subtotal Other costs (from Table 8)
Total Project Cost
$ 13,328.40
W/O labor
With Labor
$4.00 $2.98 $59.90 $3.00 $0.25 $5.50 $0.69 $1.79 $1.89 $1.79
$4.00 $2.98 $59.90 $3.00 $0.25 $5.50 $0.69 $1.79 $1.89 $1.79
$81.79 $ 15.00
$81.79 $ 15.00
Labor at $ 10.00/hr Mario Tyler Steve Renee Subtotal
$ 13,260.00
$ 3117.50 $ 3117.50 $ 3047.50 $ 3037.50 $ 96.79 $ 96.79 Table 10: Revised Project Cost Analysis
$ 12,320.00 $ 12,416.80
- 33 -
Figure 15: Deliverables Schedule
Figure 15: Deliverables Schedule
- 34 -
Figure 16: First Half of Schedules
Figure 16: First Half of Schedules
- 35 -
Figure 17: Second Half of Schedules
Figure 17: Second Half of Schedules
- 36 -
The above schedules have allowed the team to continue to stay on task. By keeping a schedule the team has been and will continue to be aware of future deadlines, as well as what tasks should be completed next. The team is on schedule.
4. Closure Material This section contains information about the clients, advisor, and team members. This section also addresses a closing summary, technical references, and appendices. 4.1 Project/Team Information Client Information: Dr. John Lamont Electrical and Computer Engineering Senior Design 324 Town Engineering Ames, Iowa 50011 515.294.3600 (office) 515.294.6760 (fax) [email protected] Faculty Advisor Information: Dr. Degang James Chen Electrical and Computer Engineering 329 Durham Ames, Iowa 50011-2252 515.294.6277 (office) 515.294.8432 (fax) [email protected] Student Team Information: Tyler J. Clifton Electrical Engineering 4510 Steinbeck Street Apt #3 Ames, Iowa 50014 641.455.9712 (cell) [email protected]
Mario A. Limonciello Electrical Engineering 4518 Steinbeck Street Apt #2 Ames, Iowa 50014 847.366.9530 (cell) [email protected]
Steve J. Walker Electrical Engineering 320 Hillcrest Avenue Apt #27 Ames, Iowa 50014 815.210.9004 (cell) [email protected]
Wong Yee Quan Electrical Engineering 1400 Coconino Road #211 Ames, Iowa 50014 515.708.4815 (cell) [email protected]
- 37 -
4.2 Closing Summary During extreme hot or cold seasons, many people, especially the elderly, are scared to travel to their mailbox multiple times to check for mail. Rather than continuously fear encountering dangers on their trip to and from the mailbox, it is much easier for the person to be notified that there is mail in the mailbox before making the journey outside. The aim of this project is to create a product that will notify the user when an object has been placed in the mailbox. Once something has been inserted into the mailbox, the user will receive an alert on a receiver located in the safety of their household. They can then travel outside only when necessary, and only have to make a single journey. After the user obtains the item from the mailbox, the device resets the receiver in the household, indicating the mailbox is now empty. The product is easily implemented in an existing mailbox and is very easy to use. An equal participation is required among the team members to guarantee the successful completion of this project. With plenty of design time, money to purchase components, and technical resources to improve the design, an automated mailbox design has been developed. The device transmits a signal back to the house to let the user know the new status of the mailbox. The device also interprets the status of the mail flag to determine if the user is attempting to send a letter. The automated mailbox is a simple, low cost solution for alerting the user about received mail. 4.3 References [1] Choosing a Microcontroller. 7 Feb. 2007 . [2] Choosing a Microcontroller for Embedded System Applications. 7 Feb. 2007 . [3] Clearwater Tech. "GE Security." Clearwater Tech. Clearwater Tech Industries. 7 Feb. 2007 . [4] Fairchild Semiconductor. "Fairchild Semiconductor - Site Search." Fairchild Semiconductor. 2006. 02 Feb. 2007 . [5] Fairchild Semiconductor. "QEE113 Plastic Infarred Light Emmiting Diode." Fairchild Semiconductor. 30 Apr. 2002. 2 Feb. 2007 .
- 38 -
[6] Fairchild Semiconductor. "QSE773 Plastic Silicon Pin Photodiode." Fairchild Semiconductor. 2000. Fairchild Semiconductor Corporation. 03 Feb. 2007 . [7] Freescale. "MC33493 Product Summary Page." Freescale. Freescale Semiconductor Industries. 27 Jan. 2007 . [8] Freescale. "MC33592 Product Summary Page." Freescale. Freescale Semiconductor Industries. 7 Feb. 2007 . [9] Hewes, John. "Light Emmiting Diodes." The Electronics Club. 2007. 25 Jan. 2007 . [10] How to choose a MicroController. 7 Feb. 2007 . [11] How to choose a Microcontroller for a wireless senior Electrical and Computer Engineering Design Project . 7 Feb. 2007 . [12] Paschotta, Rüdiger. "Encyclopedia of Laser Physics and Technology Photodetectors." RP Photonics. 11 Nov. 2006. 25 Jan. 2007 . [13] Real Elliot, The. Weblog entry. 16 Nov. 2006. Ghetto Programming: Getting started with AVR microprocessors on the cheap. 7 Feb. 2007 . [14] Refikh, M. "How to Build Your Own Wireless Receiver and Transmitter Device." EDSP. 11 Mar. 2006. 25 Jan. 2007 < http://www.e-dsp.com/how-to-build-yourown-wireless-receiver-and-transmitter-device-create-rf-in-your-embeddedapplication/>. [15] SmartHome. "Basic Sensor of Alarm System." SmartHome. SmartHome Industries. 7 Feb. 2007 .
- 39 -
4.4 Appendices
Figure 18: Transmitter Schematic
- 40 -
Figure 19: Receiver Schematic
- 41 -
