RFID ANTI-THEFT DOOR LOCK

Transcription

1 RFID ANTI-THEFT DOOR LOCK By Zhengchang Kou Stanley ang Xinyi Zhang Final Report for ECE 445, Senior Design, Fall 2017 TA: Jacob Bryan 13 December 2018 Project No. 45

2 Abstract Our project is an RFID anti-theft door lock. Unlike traditional door lock, this lock uses RFID tag as the key, so it is considerably easy to use. Moreover, it contains two anti-theft functions. When a burglary occurs, the alarm siren will ring to alarm the surrounding people, and the camera will take a photo for the burglar. It also has batteries to keep the whole system working when a power cut happens. During building the system, we burned out our camera, but all other functions work properly. ii

3 Contents 1. Introduction Objective Background Design Power Supply AC Power Adapter Battery Charger Li-ion Battery Low Dropout Voltage Regulator DC-DC Converter Control Unit MCU IR Emitter and Phototransistor Reed Switch Lock Buzzer RFID Reader Relay Conditional LED Camera Camera SD Card Software Design Costs Parts Labor Grand Total Conclusion Accomplishments Ethical considerations Future work References Appendix A Requirement and Verification Table iii

4 Appendix B RFID Door Alarm System Logic Flowchart iv

5 1. Introduction 1.1 Objective For most people, home is both the start and the end of their days. Home is also the place where people spend the most time staying in. However, home is also a private place; nobody is happy if everyone can enter his or her home without any limits. Therefore, most people install locks on their doors to prevent others to easily get inside. Nevertheless, the traditional door lock has become undependable. Sometimes, the key or the lock might be corrosive, and the lock becomes very hard to open. Many people have the experience that they plug in the key and spin it clockwise, but the door does not open. Then, they spin it counterclockwise, but it still does not open. Then, they try to spin it clockwise again, and the door finally opens. This process is absolutely annoying. Besides that, some people even meet the situation in which the keys are broken and parts of the keys are stuck inside the door. More importantly, those traditional locks do not have any anti-theft function. Burglars who master the skills of opening the locks can easily enter people s houses. Some people may think that there are so many families, so the percentage that they encounter burglaries is low. This opinion is imprudent. If they did not encounter burglaries, that would be perfect. However, if burglaries did occur and they did not have a reliable lock, the property loss could not be eliminated. Even their life safety could not be guaranteed. Our goal is to design an RFID anti-theft door lock. This lock utilizes an RFID tag to open, so it is much more convenient than the traditional lock. It only takes less than one second to open the door, and people does not need to worry about the direction to spin. Also, this lock offers two protections, both during the burglary and after the burglary. This lock contains a crime alarm and camera. If a burglar attempted to open the lock without the tag or destroy the lock, the alarm would ring to notice the surrounding people and the burglar might leave immediately. If the intruder came at night and the house owners had already fell asleep, the alarm would wake up the house owners. This is the protection during the process of a burglary. Moreover, the camera would also take a photo of the burglar so as to help the police to apprehend the criminal. The house owners and the police could arrest the criminal and retrieve their properties. This is the protection after the burglary. 1.2 Background Currently, most people still use the traditional door locks with deadbolts. A deadbolt lock contains a bolt that extends to at least one inch in diameter and be is made of hardened steel. Cutting it through is extremely time-consuming [1]. The physical design of the deadbolt door locks is considerably solid, and most burglars are unable to commit forced entries by kicking or bumping against the doors. Nonetheless, this security level could only be achieved if the deadbolt is regularly used. Lance Cronk, owner of highly rated Metro Lock Service in Portland, Ore., mentions that many homeowners find it easier to lock the doorknob and often neglect to lock the deadbolt [2]. A doorknob is usually not solid enough to bear a strong impact. Also, even if people lock the deadbolt, those locks are susceptible to lock bumping [1]. Therefore, many people s houses are actually in danger, but they are not aware of this fact. However, unlike the traditional door lock, our lock uses a deadbolt and can still bring people with very convenient 1

6 experience. Our lock uses an RFID to control the lock, so people can unlock the door in less than 1 second. Also, the deadbolt inside can provide high security level, just like the deadbolts in those traditional door locks. Moreover, the traditional door locks are only able to check a forced entry in some extent. Once the burglar breaks the defense, those locks are unable to stop the intrusion. Because our design has a high-decibel alarm siren, our lock is able to make a considerably loud alarm, which can make the surrounding people vigilant and possibly stop an underway criminal behavior. In the market, there are several security systems with comprehensive functions. Those systems can detect intrusion and some environmental hazards, but they are not locks. Also, customers have to continuously pay to the security company for the surveillance service. For example, ADT is a popular security system provider. Its cheapest service, including 24-HR monitoring, door/window sensors, infrared motion detector, and alarm siren, costs $36.99/month [3]. This price is like to purchase a new electric lock every 3 months. In contrast, our design is not only a security system, but also a durable and convenient door lock. Our design also contains the buzzer alarm and provides another useful anti-theft functions: camera. The camera is similar with the surveillance function: they can both capture the aspect of the intruder. However, people do not need to pay for this function, and our design is much less power-consuming. The ADT security system also has a backup battery, just like our design, but the duration is only 12 hours. The battery in our design can reach approximately 55 hours. 2

7 2 Design Our project is composed of three major modules: power supply, control unit, and camera. The power supply module supplies enough steady power to the circuit. The control unit controls all peripheries and makes the whole system achieve all designed functions. The camera module takes and stores photos. Figure 1 Block Diagram 2.1 Power Supply The power supply module is to provide sufficient and steady power to all of the other components when they are operating. This module includes the AC adapter, battery charger, battery, voltage regulator and dc-dc converter. The battery and battery charger are used to provide backup power supply to the system when the power is cut off for any reasons. The voltage regulator is used to provide steady voltage to MCU and other periphery components that need 3.3V. The dc-dc converter is to provide power to the lock which requires 12V AC Power Adapter Design Procedure Our lock requires a reliable power supply, so we choose the power outlet. In case people may want to use our lock out of the US, the adapter must be able to convert input voltages from 100V to 240V Design Details We use the power outlet to continuously charge the Li-ion batteries and use the power from the batteries to power up the whole system. The output voltage is set to 5V, and the adapter sends this voltage to the battery charger. 3

8 Verification When the input voltage is 110V, the output voltage of the adapter is 4.989V. This satisfies with our requirement. Since we do not have power supply over 110V, we cannot test if this adapter works with voltage above 110V. However, the label on the adapter shows that the input voltage can be from 110V to 240V Battery Charger Design Procedure The battery charger is used to charge up the battery. We use the lithium ion battery which requires 4.2V charging voltage. We choose Texas Instrument's BQ21040 battery charger Design Details We have to make sure that the battery charger IC can perform the normal function which is to provide steady 4.2V output. We implement the circuit according to the datasheet. Figure 2 is the schematic. Figure 2 Circuit of Battery Charger Verification After we implemented the circuit as above and soldered all the parts on the board, we tested the battery charger output voltage. The result was 4.196V. This voltage is in the range of 4.16V~4.24V, which is described in the design document Li-ion Battery Design Procedure We use battery as backup power supply in case a power cut occurs Design Details We use 4 Li-ion batteries, and each battery has 9800mAh. These batteries are charged by the battery charger with 4.2V input voltage. The output voltage of these batteries is 3.7V. The low dropout regulator transfers it into 3.3V voltage. We require the battery can provide power for the whole system for at least 48 hours. Based on our calculation, it can last for 55 hours. Table 1 Current Output of LDO Devices connected to LDO Current (ma) MCU 7.94 Buzzer 50 LEDs 40 4

9 IR Emitter 20 Phototransistor 6 RFID Reader 20 Relay 40 Camera 110 Total Current Input of LDO = mA 3.3V 3.7V = 262.2mA (2.1) Current of Lock = 450mA (2.2) Total Current Consumption = = 712.2mA (2.3) Duration of Batteries = mAh 712.2mA = 55 hours (2.4) Verification The measured total current consumption is mA. Based on Equation (2.5), the duration of the battery is approximately 51.5 hours, which still meets our requirement. Duration of Batteries = mAh hours (2.5) Low Dropout Voltage Regulator Design Procedure The voltage regulator is used to provide the MCU and other periphery components with 3.3V power supply. We want the voltage to be as steady as possible when the current driving is changing. In this way, we choose Texas Instrument's TLV704 low dropout voltage regulator Design Details This LDO gets 3.7V voltage from the Li-ion battery and outputs 3.3V voltage. We follow the datasheet of this regulator to implement the circuit. The details of the circuit are shown in Figure 3. Figure 3 Circuit of Low Dropout Voltage Regulator 5

10 Verification After we implemented the circuit as above and solder all the parts on the board, we tested the output voltage from the power supply pin of the ports that used to connect periphery component and measured this voltage. When the whole system is operating, the result was 3.296V, which was in the range of the requirement DC-DC Converter Design Procedure The converter is used to provide the lock with 12V power supply. The current consumption of the lock is up to 450mA at 12V, so we need a high-power DC-DC converter. In this way, we choose Texas Instrument's PTN04050C dc-dc converter. The output voltage of this dc-dc converter is controlled by the setting resistor Design Details We follow the datasheet of this regulator to implement the circuit. The detail of the circuit is shown in Figure 4. We choose the setting resistance according to Equation (2.6). R LMN = 15kΩ PQ RPQSTQ 2.94kΩ = 1.345kΩ (2.6) Figure 4 Circuit of DC-DC Converter Verification After we implemented the circuit as above and soldered all the parts on the board, we tested the output voltage from the power supply pin of the ports that used to connect lock and measured this voltage when the lock was locked. The result was 12.08V, which was in the range of the requirement. 2.2 Control Unit The control unit is to accomplish the main functions of this lock. It contains a micro control unit to send data to the lock, buzzer, and LED. When the RFID reader detects a proper tag, it will send a signal to the MCU, and the MCU will unlock the door and turn on the green LED. If an incorrect tag is detected, the red LED will be turned on. If the IR emitter and phototransistor notice that the door is opened and no signal from the RFID reader goes to the MCU, the MCU will trigger the alarm and ask the camera to take a picture. 6

11 2.2.1 MCU Design Procedure Originally, we proposed to use Texas Instruments MSP430FR2310 as the MCU for the system. MSP430 is a low power consumption micro controller which can elongate our system operation time when the power supply is cut off. It is also a very compact MCU which is helpful to reduce the size of the actual board we use. However, during the progress of design, we realized that MSP430 is quite time consuming for software design. Then we switched to the Atmega 328P MCU, which is compatible with Arduino board so that we could program the MCU with Arduino board and then migrated the chip to our PCB. Also, we do not need to implement any programming circuit on our board Design Details According to the datasheet of Atmega 328P, we have to provide an off-chip crystal oscillator as the external clock source to the MCU. We choose the Cstce16M as the crystal oscillator which is the same as the original Arduino board. We provide 3.3V to power up this MCU. Figure 5 shows how we design the connection in our PCB. Figure 5 Circuit of MCU Verification We wrote a simple program which would enable all the IO pins to digital high. Then we used digital multimeter to measure the voltage at the IO to make sure each IO pin has the high voltage as we want. Also, we need to write out a short program to make sure the MCU can be programmed. After verifying, all the IO pins had 3.3V, which matched what we wanted. The short program, which intended to blink the LED on the Arduino board, was able to make the LED blink. 7

12 2.2.2 IR Emitter and Phototransistor Design Procedure The IR emitter and phototransistor are used to detect if the door is opened. If the phototransistor does not detect the IR, MCU can know that the door is opened Design Details Figure 6 Circuit of IR Unit The minimum logic-high voltage of MCU is 0.3V. Based on Equation (2.7), the largest value V CE can be is 3V. We choose to use 100W resistor, and the current is 3mA. In that case, the voltage across the resistor should be 0.3V, which satisfies the minimum voltage input of MCU. W.WQSQ X Z = I \ (2.7) Figure 7 Light Current vs. Collector - Emitter Voltage [4] For the arrangement of the IR emitter and phototransistor, we came up with three approaches. The approach we used is demonstrated in Figure 7: 8

13 Figure 8 Arrangement of IR Emitter and Phototransistor #1 By placing the IR emitter and phototransistor like this, they can sensitively detect the condition of the door. The disadvantage is the long wire to power up the IR emitter. We also considered two alternative arrangements, which are demonstrated in the following: Figure 9 Arrangement of IR Emitter and Phototransistor #2 Figure 10 Arrangement of IR Emitter and Phototransistor #3 In the Figure 9 arrangement, we can use a shorter wire, but the distance between the IR emitter and phototransistor becomes much longer. As a result, the interface can be easily blocked by some unpredictable things, which cause the whole system unable to work properly. 9

14 We think the Figure 10 arrangement is the best solution because we can avoid a long wire. However, the sensor we use is not sensitive enough, so it is considerably hard for us to place the IR emitter and phototransistor at proper locations. In industrial production, we can use this method because we can make the design more standard Verification We powered up the IR emitter and connected the phototransistor to a 100W resistor. The voltage across the resistor was 0.37V, which was higher than the minimum logic-high voltage of MCU. Therefore, the result meets our requirement Reed Switch Design Procedure In order to achieve a higher security level, we add a reed switch. MCU considers the door as opened when either IR sensor or reed switch shows that the door is opened Design Details We place the reed switch on the lock and a strong magnet on the door frame. When door is closed, the reed switch is very close to the magnet, so the reed switch is closed. In that situation, current can go through the reed switch. If the door is opened, the reed switch is open, and current can no longer go through it. Then, MCU knows that the door is opened Verification We connected the reed switch to the multimeter and opened the continuity test. At first, the magnet we used was not strong, so the reed switch was not very sensitive. After we changed to a neodymium magnet, the performance of the reed switch became very well Lock Design Procedure The lock we choose has a deadbolt, which makes it very solid and reliable. It is locked with power and unlocked without power. When we improve our project, we will find a lock operating oppositely in order to save power Design Details The operating voltage of this lock is 12V, so we have a DCDC converter to convert 3.7V to 12V. Since the maximum output current of the converter is 2.4A, the working current of this lock has to be less than that. It must also be quickly unlocked when the power is cut Verification The measured working current of this lock is 450mA. We have also tested if it can response quickly when we supply power and cut power. The result is satisfying; it can be locked and unlocked without any delay, and the current it needs makes it work properly in the whole system Buzzer Design Procedure If a correct RFID tag is not detected and either sensor shows that the door is opened, the buzzer will ring to notice the surrounding people. In most cases, the burglar will choose to leave 10

15 immediately. Also, if the burglar comes at night, the buzzer has to be loud enough to wake up the house owner Design Details In order to make the surrounding people vigilant, the buzzer must be really loud. The buzzer we choose is 110dB. The calculated decibel at 20m away is: log ^.R_ P^_ = 86.99dB (2.8) Verification We connected the buzzer into our system, provided it with 3.3V voltage, and measured its decibel at 20m away. The measured decibel is 83.8dB, so it is loud enough to alarm people RFID Reader Design Procedure The main reason that people tend to ignore the deadbolt is that using the traditional key is not convenient, so we decide to use RFID to make deadbolt much easier to use. In fact, RFID has some disadvantages in its security level. In our future improvement, we would consider changing the RFID to near-field communication (NFC), a specialized subset within the family of RFID technology. NFC has a higher security level than RFID does. It is designed for contact or very close to contact information [5]. RFID has one-way communication, and NFC has two-way communication: an NFC device is capable of being both an NFC reader and an NFC tag [6]. However, this feature is not so useful in an electronic lock. What we concern is the difference in the security level between these two technologies. The operating frequencies for both RFID and NFC are MHz. Nonetheless, the typical scan distance for RFID can reach up to 1m while the scan distance for NFC is less than 10cm [6]. A person can stand 1 meter away from an RFID tag and use an antenna to copy the unique ID of the RFID tag, but for NFC, people would not be able to easily gain the information stored in NFC devices. In the future development, we will consider using NFC, instead of RFID, in order to improve the security level Design Details The RFID reader has an operating voltage of 3.3V because the output voltage of the LDO is 3.3V. It uses SPI to communicate with MCU. Also, it has a short scan distance. If the scan distance is too long, the door could be unintentionally opened when the homeowner just wants to walk pass Verification The requirement we set for the RFID reader is to have a scan distance shorter than 10cm. When we actually tested it, it could not detect the tag once the distance went above 3cm. This result is satisfying because it can ensure that the homeowner would not open the door unintentionally. 11

16 2.2.7 Relay Design Procedure As the MCU cannot control the 12V output directly. We need some other component to control this 12V output to drive the lock. We choose the Omron G6D-1A 5V dc to control the 12V output Design Details Figure 11 Circuit of Relay Because our MCU is operating at 3.3V, which is in the range of the relay's coil voltage range. So we connect one of the pins from MCU directly to relay's control pin Verification When we output a digital high signal from the MCU to relay. The switch pins are short according to the continuity test of multimeter Conditional LED Design Procedure The LEDs are used to explicitly show the status of the system Design Details There are two LEDs: green and red. They are both powered by the 3.3V LDO. When a proper tag is detected, the LED is green. When an incorrect tag is detected, the LED is red. When an incursion occurs, both the red LED and the green LED are on Verification We connected those LEDs to a 3.3V voltage source, and they were green and red, so they fitted our design. 2.3 Camera When the lock detects a person who attempt to intrude, the MCU will send a signal to the camera, and the camera will take a photo for that person. The photo is saved in the MicroSD card. The homeowners and the police can use the photo to arrest the intruder. 12

17 2.3.1 Camera Design Procedure If a person tries to intrude, his or her face is usually closed to the lock, so we can simply install the camera in the lock, instead of the place closing to the peephole. However, capturing the face of the person is not our only concern. Sometimes, the camera might fail to capture the face due to some factors, such as light. If the camera could capture some details of the person s clothes or accessories, that would be considerably helpful. Therefore, the resolution has to be relatively high Design Details The camera is powered by the 3.3V LDO. It has a white wire to control. When the MCU gives 3.3V voltage to the white wire for less than 1 second, it takes a photo Verification When we tested the camera two days before our demo, we forgot to use a resistor. As a result, the camera was burned out. We did not have enough time to get a new camera, so we have no other choice but to discard this function SD Card Design Procedure The MicroSD card is used to store the photos. When we improve our design in the future, we plan to delete this part because we want to immediately send the photo to the homeowner's phone. By doing so, the intruder cannot take away the photo when he notices the camera Design Details The photo resolution of the camera is 1280x720. Since the camera is not often used and the typical size of a 1280x720 photo is less than 500kb, the storage can be relatively small. We choose this 8GB MicroSDHC card because those cards with small storages are rare in the current market. 8GB card is an economical option Verification We stored some random files into this MicroSD card, and card itself is functional. However, since we burned out our camera, the card became meaningless. 2.4 Software Design Design Procedure This section mainly discusses the system operation of the RFID door alarm system. Originally in our proposal, our team proposed to use the Texas Instruments MSP430FR2311 to be the processor of our RFID alarm. But since MSP430FR2311 only supports low level C programming language and it does not have sufficient library for the RC522 RFID protocol, then our team decided to switch to a more common use microprocessor, Atmega 328P. With the Atmega 328P, our team established the connection between the microprocessor and RFID reader within a week. 13

18 2.4.2 Design Details Using Atmega 328P, we were able to find a useful RFID-Arduino library from GitHub [7] and a sample code for the RFID protocol using Serial Peripheral Interface [8]. We modified the code to be the skeleton code of our RFID door alarm system. The system is designed to be a state machine which contains seven different states. These seven states are: Active State, Verification State, Success State, Failed Verification State, Wait For Door State, Reverification State, Alarm Triggered State. A flowchart of the system operation is attach at Appendix B. Table 2 is the state transition table. Table 2 State Transitions and Actions Table Current State Action 1 Action 2 Next State 1 Next State 2 Side Effect(s) ACTIVE STATE RFID card Brutal force VERIFICATION ALARM Monitor IR and sensed STATE TRIGGERED reed Sensors VERIFICATION STATE SUCCESS STATE FAILED VERIFICATION STATE WAIT FOR DOOR STATE REVERIFICATION STATE ALARM TRIGGERED STATE Check card info n/a SUCCESS STATE Wait for door close n/a WAIT FOR DOOR STATE STATE FAILED VERIFICATION STATE N/A n/a Door open, Deactivate IR and reed sensors n/a n/a ACTIVE STATE N/A Red led light up IR detector receives signal AND reed switch closed Check card info correct Reset n/a ACTIVE STATE N/A Lock remains unlocked Check card info incorrect RFID Card Sensed SUCCESS STATE ACTIVE STATE ALARM TRIGGERED STATE REVERIFICATION STATE n/a 1.Take picture with camera 2.Red and green LEDs ON 3.Alarm buzzes for 5 seconds Design Verification To Verify the RFID door alarm system is working correctly, we need to verify each state to make sure each state is functional (having correct actions, side effects and next state transition). Active State: Verification: Using a correct RFID card and tap on the RFID reader should activate the alarm system and lock the door. Result: The correct RFID card could lock the door after a 3-second preset delay. Verification State: Verification: Using any RFID cards should help the alarm system to transit either success state or failed verification state. 14

19 Result: Used a correct RFID card, the green LED was lit on indicates its state was transited to success state; used an incorrect RFID card, the red LED was lit on indicates its state was transited to failed verification state. Success State: Verification: The locking status is changed from locked to unlocked, green LED lights up, and door can be opened. Result: After a tap of a correct RFID card, the lock was unlocked, and the door was able to open. Failed Verification State: Verification: The red LED should be lit up, and the door remains locked. Result: After a tap of an incorrect RFID card, the lock remained lock, and the red LED was lit up. Wait For Door State: Verification: The door remains unlocked until the door is closed, and the alarm system will be activated after a delay. Result: Door was locked after closing. Simulated break in and alarm were triggered. Reverification State: Verification: The system transits to success state or alarm triggered state. Result: Used a correct RFID card, the system transited to success state; an incorrect RFID card didn t make any effects on the system. Alarm Triggered State: Verification: Buzzer sounds, both LEDs light up, camera takes picture, and door remains locked. Result: After triggering either IR or reed switch, alarm was on. Buzzer sounded for 5 seconds, both LEDs lit up. Unfortunately, the camera was burnt out while testing. After all the verifications, our system worked flawlessly without any bugs. The only imperfection for us was we were not able to purchase a new camera on time to improve the door alarm system. 15

20 4. Costs 4.1 Parts Table 3 Parts Costs Part Manufacturer Quantity Retail Cost ($) Bulk Purchase SoulBay 12W Universal Multi- Voltage AC/DC Adapter Battery Charger BQ24040 KS Universal Li-ion Rechargeable Batteries DCDC Converter PTN04050C Low-Dropout Regulator TLV704 Actual Cost ($) Cost ($) SoulBay Texas Instruments KS Texas Instruments Texas Instruments ATmega328P Elegoo IR Emitter Honeywell WP3A10SF4BT Phototransistor Fairchild QSE122 RC522 RFID Reader Sunfounder Electric Drop Door Unbranded Lock Z9W0 Uxcell Electronics Uxcell Buzzer LZQ-3022 Round LED Light Unbranded Bulb BJT 2N2222 Farnell Relay G6D-1A Omron Mini Spy Trigger Camera for Photo or Video Adafruit Reed Switch Cylewet CT1065 Neudymium Magnet Super Magnet Total Labor Table 3 Labor Costs Name Hourly Rate ($) Hours Total ($) Total x 2.5 ($) Zhengchang Kou Stanley ang Xinyi Zhang Total

21 4.3 Grand Total Table 4 Grand Total Section Total ($) Labor Parts Grand Total

22 5. Conclusion 5.1 Accomplishments Since our camera was burned out, we had to discard that function. However, all other components work very well. We have overcome many challenges during the process, so we consider our project as a remarkable success. 5.3 Ethical considerations The ACM code of ethics mentions that engineers are required to respect the privacy of others [9]. In fact, this is also the main goal of our project. For most people, their houses are the most important place, and they absolute want to protect the privacy in a considerably high level. Our RFID anti-theft lock is able to accomplish this desire for people. Moreover, based on the IEEE code of ethics, engineers should improve the understanding of technology; its appropriate application, and potential consequences [10]. Many people know the necessity of protecting their houses; they just do not know the appropriate approach. We design this lock not only to provide convenience and high-level protection, but also to make people realize the reliable approach to protect their privacy and property. 5.4 Future work Although our RFID door alarm system provides a decent home security to the customers, but since we do not own a house, we still have not experienced many different scenarios which could possibly void our security system. Therefore, we have come up as many ways as possible to improve our door alarm system in many aspects. NFC: The door access can be replaced with the NFC protocol instead of the RFID since NFC is a two ways communication and it provides higher security. Ultralow Power MCU: Due to time constraint, we were not able to implement the door alarm system using the ultralow power Texas Instruments MSP430FR2311. In the future, if we used MSP430, it would greatly reduce the power consumption of our door alarm system and have extended operational time while operating in backup battery mode. Photo Storage: As professor Xiaogang Chen pointed out in our presentation, the SD card could be easily removed by the intruders, then we would have no way to know who the intruders were. Therefore, if the alarm is triggered, the alarm system can take a picture and send it to a local solid-state drive server via WIFI/Bluetooth which can preserve the images being stolen in the SD card. Mobile Alarm App: We have thought about developing an ios/android application which would receive alarm message from the door alarm system. In this way, the door alarm system is connected to WIFI and can send the homeowner if someone has broken in to his/her house. Also, the homeowner will have the option to notify the local police by sending the location of the house and the intruders pictures by tapping the button. There are many improvements we can make in the project, and by improving the alarm system, we should help more people feeling safe and reduce the criminal rates significantly. 18

23 References [1] Home Security Systems Guide, What is Deadbolt Lock and its Benefits, [Online]. Available: [Accessed: 13-Dec-2017] [2] LaFollette, Locksmiths Say Deadbolt Key to Home Security, [Online]. Available: [Accessed: 13-Dec-2017] [3] ADT, ADT Monitoring, [Online]. Available: [Accessed: 13-Dec- 2017] [4] Fairchild, QSD123, QSD124 Plastic Silicon Infrared Phototransistor, 2016 [Online]. Available: [Accessed: 13-Dec- 2017] [5] Thrasher, RFID vs. NFC: What s the Difference?, [Online]. Available: [Accessed: 13-Dec-2017]] [6] NFC.Today, The Difference between NFC and RFID, [Online]. Available: [Accessed: 13-Dec-2017]] [7] miguelbalboa/rfid, GitHub, [Online]. Available: [Accessed: 13- Dec- 2017]. [8] การใช งานโมด ลอ าน RFID ก บ Arduino แบบง ายๆ, Ioxhop.com, [Online]. Available: 3%E0%B9%83%E0%B8%8A%E0%B9%89%E0%B8%87%E0%B8%B2%E0%B8%99 %E0%B9%82%E0%B8%A1%E0%B8%94%E0%B8%B9%E0%B8%A5%E0%B8%AD %E0%B9%88%E0%B8%B2%E0%B8%99-rfid- %E0%B8%81%E0%B8%B1%E0%B8%9A-arduino- %E0%B9%81%E0%B8%9A%E0%B8%9A%E0%B8%87%E0%B9%88%E0%B8%B2 %E0%B8%A2%E0%B9%86. [Accessed: 13- Dec- 2017]. [9] ACM Council, ACM Code of Ethics and Professional Conduct, [Online]. Available: [Accessed: 13-Dec- 2017] [10] ieee.org, IEEE IEEE Code of Ethics, [Online]. Available: [Accessed: 13-Dec- 2017]. 19

24 Appendix A Requirement and Verification Table Table 5 System Requirements and Verifications AC Adapter Requirement Verification Verification status ( or N) 1. Must be able to convert AC input voltages from 100V to 240V. 2. The output voltage must be 5V ±5% VDC with a current at least 1A. 1. Li-ion battery charges to V when a continuous 5V input voltage is applied with a supply current of 1A 2. Charging at maximum current and voltage can be sustained below 50 C. 1. Must be able to provide power for the system for at least 48 hours without power outlet. 1. The output voltage has to be 3.3V±2% when the load current is 150mA and the input voltage is 3.6V to 4.2V. 1. a. Swap the input voltage from 100V to 240V. b. Test the output voltage change when a 1W resistor is the load. Battery Charger 1. a. Discharge a li-ion battery to 3.7V cell voltage. b. Charge the battery at the output of the charger without limiting current. c. At the termination of the charge cycle, use a voltmeter to check the voltage of the battery. 2. a. Throughout the charging cycle observe the temperature. Use an IR thermometer to ensure that the temperature is below 50 C. Battery 1. a. Calculate the total current consumption. b. Calculate the total mah of batteries. c. Divide the total mah by the total current consumption to make sure that the duration is longer than 48 hours. Low Dropout Voltage Regulator 1. a. Connect a 220W resistor to the output pin. b. Connect the input to the power supply. c. Measure the voltage of the resistor with a voltmeter. Swap the input voltage from 3.6V to 4.2V. Measure the output voltage. 20

25 1. When the input is from 3.2V to 4.2V and the load current is at least 450mA, the output voltage has to be 12V±5% 1. The MCU should be able to send digital high to each of its output individually, read analog value on each of its input individually, and communicate through SPI. 1. The phototransistor must be able to detect the IR emitter within 10cm. 2. The phototransistor must be able to detect the emitter at up to 40 C. DCDC Converter 1. a. Connect the input of the converter to the power supply and the load of the converter is 25W resistor. b. Swap the input voltage from 3.2V to 4.2V and measure the output voltage. MCU 1. a. Write a short program to loop each of the digital output and output a square wave on them. b. Use oscilloscope to check the waveform. c. Write a short program to sample the analog value on each of its analog port and display them on the serial monitor. d. Build the SPI communication code and check if the RFID is right. e. Send the result to the serial monitor. IR Emitter and Phototransistor 1. a. Power up the IR emitter and phototransistor with a 1.5V voltage source. b. Place the phototransistor 10cm away from the emitter. c. Connect a 100W resistor to the emitter of the phototransistor. d. Use the phototransistor to detect the IR. e. Measure the voltage across the series resistor. Ensure that the current through the phototransistor is above 3mA. 2. a. Before performing the verification in 1, use a hair dryer to heat the emitter. b. Use a thermometer to measure the surrounding temperature. c. When the temperature reaches 40 C, turn off the hair dryer and perform the verification in 1. 21

26 1. The reed switch must be closed when a magnet is close to it. 1. The working current has to be less than 2.4A. 2. Must be quick unlocked when the power is cut. 1. The noise must be at least 80dB at 20m away from the buzzer. 1. The reading distance must be less than 10cm. 2. The operating voltage must be 3.3V±2%. 1. Must be able to switch on when a 3.3V signal voltage is sent to the relay. Reed Switch 1. a. Connect the reed switch to the multimeter and open the continuity test. b. Put a magnet close to it. c. Check the continuity on the multimeter. Lock 1. a. Use a current generator to apply 450mA (based on the description) to ensure the lock works. 2. a. Stop the power supply. b. Ensure that it is unlocked immediately. Buzzer 1. a. Connect the buzzer to a 3.3V voltage source. b. Use a decibel meter to measure the decibel at 20m away from the buzzer. Ensure that the noise is above 80dB. RFID Reader 1. a. Perform the reading in the distance from 2cm to 10cm in 2cm step with a ruler to measure the distance. b. Once the distance reaches 10cm, increase the distance by 0.1cm each to perform the reading. c. ensure that the reader cannot detect the RFID tag once the distance is above 10cm. 2. a. Swap the input voltage of RFID reader from 2.8V to 3.4V. Check whether it works properly. Relay 1. a. Power up the relay with 3.3V voltage. b. Connect the relay to a 12V voltage source. c. Send a 3.3V voltage to the relay. 22

27 1. Must have green light and red light. 1. The photo resolution has to be at least 1280x The storage must be at least 512 MB and less than 32 GB d. Use a voltmeter to measure the voltage across the resistor. Ensure that the voltage is 12V± 5%. Conditional LED 1. a. Connect those LEDs to a 3.3V voltage source. b. Ensure that there are green and red LEDs. Camera 1. a. Connect the red wire to a 3.3V voltage supply and connect the black wire to the ground. b. Connect the white wire to the voltage supply for less than 1 second to take a photo. SD Card 1. a. Plug the MicroSD card into a laptop to check the storage N 23

28 Appendix B RFID Door Alarm System Logic Flowchart Figure 12 Flow Chart 24