ECE 445 Senior Design. IoT Device Monitoring System for Hotels Group 13. Design Review

Transcription

1 ECE 445 Senior Design IoT Device Monitoring System for Hotels Group 13 Design Review Milan Dasgupta: mdasgup2 Muratza Haider: mhaider2 Willie Wang: wwang53 TA: Cara Yang 10/9/2015

2 1. Introduction Table of Contents 1.1 Statement of Purpose Project Objectives Goals and Benefits Functions Design 2.1 Block Diagrams Overall Block Diagram Temperature Sensor Dust Sensor Current Sensor Descriptions of Blocks P1 WiFi Enabled Microcontroller Lithium Ion Battery LD2951ACN 3.3G Voltage Regulator Temperature Sensor Dust Sensor a NPN BJT Transistor Current Sensor a Capacitor and Resistors b A1301 Hall effect Sensor c TPS76350 Q1 Voltage Regulator Microcontroller and Server Flowcharts Microcontroller Flowchart Server Flowchart Simulations and Calculations Simulation Calculation a Dust Sensor b Current Sensor c Memory Storage d Battery e 3.3 V Voltage Regulator f 5 V Voltage Regulator Schematics

3 2.5.1 P1 Microcontroller with Power Supply Current Sensor Dust Sensor Temperature Sensor Block Level Requirements and Verification 3.1 Requirements and Verification Tolerance Analysis Safety and Ethical Considerations Ethical Considerations Safety Considerations Cost and Schedule 4.1 Cost Analysis Labor Costs Part Costs Total Tasks Schedule References

4 1 Introduction 1.1 Statement of Purpose IoT is an emerging field with potential of various applications with regards to remote sensing. Companies have been working on installing sensors in areas such as airplanes, heavy oil drilling machines, and large equipment but the hotel space has not been breached by the IoT space yet. The purpose of this project is to affix sensors in a hotel room to monitor a few parameters that are essential in ensuring quality of the room. We propose installing a current sensor to monitor the run time quality of the television, a temperature sensor to ensure the temperature in the room matches with the temperature set on the central air conditioning unit of the room and a dust sensor which will monitor the density of dust particles in the room. These sensors will transmit their readings to a web based server through WiFi which can be accessed by the customer through a secure a web portal from anywhere in the world, or through a LAN connection, depending on the customer s requirements. To allow ease of installation and flexibility in placement of these sensors in a room, all sensors will be wireless, with only a battery and the sensor itself being the wired components in the system. This technology will allow hotels to monitor the status of their hotel rooms remotely without sending maintenance staff to all rooms to check for any issues, which will save the hotel labor costs and time, that would have otherwise been spent in checking every room through manual inspection. 1.2 Project Objectives Goals and Benefits Periodically monitor operation status of rooms with minimum manual supervision Easily detect and repair broken equipment in a room through smarter data reporting tools Increase overall customer satisfaction through a smoother experience Functions Flexible placement of sensors through wireless capabilities Access to sensor data through web portal using any internet access point alerts generated whenever sensor reading thresholds are breached 3

5 2. Design 2.1 Block Diagrams High Level System Architecture Block Diagram As can be seen in Figure 1 below, all sensors consist of at least three main parts. A power circuit to ensure all components receive the correct voltage and current to power on, a sensor to monitor each variable being monitored, the P1 WiFi enabled microcontroller which periodically collects data from the installed sensors and transmits data collected at set intervals using WiFi connectivity to a web server, where data storage and analysis will occur. Block diagrams for all sensors below have been broken into their individual, lower level block diagrams from Figures 2 to 4. Figure 1: High Level Block Diagram showcasing system architecture 4

6 2.1.2 Temperature Sensor The block diagram in Figure 2 showcases the connection of our digital temperature sensor (DS18B20) to the P1 microcontroller. The microcontroller will be powered using a 6Ah Lithium Ion rechargeable battery, which will output 3.7V. However, as the microcontroller requires an average voltage of 3.3V to power it on, a voltage regulator (LP2951ACN 3.3G) that can take in input voltages of up to 30V and output a clean voltage of 3.3V at maximum of 100mA current is being used to regulate the battery voltage to the requirements of the microcontroller. Figure 2: Temperature Sensor Block Diagram 5

7 2.1.3 Dust Sensor The block diagram in figure 3 showcases the connection of the optical dust sensor (Sharp s GP2Y1010AU0F) which will be used to detect the density of dust in the air in a room. A NPN transistor, which drives its internal LED to detect dust particles which is driven through a PWM signal provided by the microcontroller, is also connected to the optical dust sensor. The dust sensor is also connected to the P1 microcontroller which can collect and transmit its readings to the web server. Figure 3: Dust Sensor Block Diagram 6

8 2.1.4 Current Sensor Figure 4 below shows how a current sensor is connected to our microcontroller. As the current sensor will be built from scratch for this project, the block diagram outlines in detail what internal components the current sensor consists of and the internal connection between them and the microcontroller. Figure 4: Current Sensor Block Diagram 7

9 2.2 Descriptions of Blocks P1 WiFi Enabled Microcontroller Summary We plan on using the P1 WiFi Enabled Microcontroller developed by Particle, which is the microcontroller chip for their Photon prototyping board. This block will collect data from the sensors and because of it s inbuilt WiFi chip, will allow data to be transmitted to a web server. This block will also help save power by switching from active mode where the WiFi module is turned on, to sleep mode where the microcontroller will continue to run and collect and store all data on its inbuilt 1MB flash memory. Chip operation details were found on the datasheet [5] provided by Particle. Inputs There will be four input software serial communication ports that will be used for this project. Since each sensor will have its own microcontroller for collection and communication, not all four of these input communication ports will be utilized by all sensors. The current sensor s instrumentation amplifier and the air sensor will be connecting to two separate analog pins of the microcontroller. The temperature sensor will be connecting to one of the microcontroller s digital pins. Outputs The microcontroller will have two outputs. One will be from an analog pin which can output a PWM signal to the NPN transistor, which is driving the internal LED of the optical dust sensor. The other output of the microcontroller will be through it s WiFi module through which it will transmit sensor data to the web server. Figure 5. P1 microcontroller from Particle [5] 8

10 2.2.2 Lithium Ion Battery Summary We chose to use the 3.7V, 6Ah Polymer Lithium Ion Battery for its voltage range and high battery capacitance because with our goal for wireless sensors, we needed a battery that could last more than 30 days and also be rechargable, giving the user the ability to recharge the battery. Inputs There are no inputs to this battery. Outputs The battery outputs 3.7V. Figure 6. LIthium Ion Battery 9

11 2.2.3 LD2951ACN 3.3G Voltage Regulator Summary We plan on using a 6Ah Lithium Ion battery with an output of 3.7V. As the P1 microcontroller has a normal operating current of 80mA with the WiFi module turned on and it needs an average voltage of 3.3V to run optimally, the LD2951ACN 3.3G voltage regulator provided the perfect voltage regulation for our needs. Inputs The input to the voltage regulator will be 3.7V from the Lithium Ion battery. Outputs The voltage regulator will have an output of 3.3V, with a max output current of 100mA. Even though the P1 microcontroller may not operate at currents above 80mA, the voltage regulator provides the correct output voltage for this project. Figure 7. LD2951ACN 3.3G Voltage Regulator 10

12 2.2.4 DS18B20 Temperature Sensor Summary For the purposes of this project to accurately measure temperature readings of the room, the DS18B20 temperature sensor will be used. With its high accuracy, wide temperature measurement range ( 67 F to 257 F) and physical protection from environmental sensors, it is the perfect sensor for our use case. The sensor will connect with the microcontroller and its sensor circuit through an audio jack, thus allowing for swapability of sensors. Inputs The VDD pin (red wire) is the input voltage pin through which voltage is supplied to the sensor. The VDD pin has a voltage operating range of 3 to 5.5V. Outputs The DQ or Data In/Data Out pin (white wire) is the pin that connects to the digital pin of the P1 microcontroller to provide the temperature reading using logic values. A pull up resistor of 4.7kOhms between the VDD pin and DQ pin will be installed to ensure the DQ signal provides a valid logic level. Figure 8. DS18B20 Temperature Sensor 11

13 2.2.5 Dust Sensor Summary The dust sensor we will be using is the Sharp GP2Y1010AU0F. This sensor operates by utilizing the optical sensing system. An infrared emitting diode (IRED) and a photodiode are diagonally arranged into this device. It detects the reflected light of dust in air. This sensor is fairly accurate and can detect very fine particle like the cigarette smoke. We will configure our circuit around the sensor using the datasheet [1] from Sharp. The optical sensing system works according to application datasheet [2]:light from the IRED is spotted with a lens and a slit as shown on chart A in Figure 11. Also for the photodiode, a lens and a slit is positioned in front of it to detect light reflection efficiently. Area where those two optical axis cross is detection area of the device. Chart B shows what is happening inside of the device when no dust exists. The device still outputs voltage even when dust is not being detected. In this situation, sensor outputs a voltage of 0.9V which the datasheet[1] defines as V OC. This is because light emitted from the IRED reflects back while some part of it still gets to the detector. Chart C shows when dust and/or cigarette smoke is detected. In this situation, the photodiode detects the light reflected from the particle. Current in proportion to amount of the detected light from the detector will be outputted to an amplifier circuit. The sensor will then output an analog voltage to the microcontroller for data processing. Figure 9. Principles of Dust Detection[2] 12

14 The sensor will connect with the microcontroller through a 6 pin female to female JST connector. Inputs The dust sensor requires a voltage supply V CC of 0.3V to +7V. We will use the Voltage Regulator outputting 3.3V to power the Dust sensor. The IRED flashing will also be controlled with a PWM signal which will be outputted from the microcontroller. Outputs The sensor will output an analog voltage to the microcontroller starting with 0.9V when there is no dust and increases by 1V per 0.1mg/M 3 of dust particles. Figure 10 GP2Y1010AU Dust Sensor[1] 2.2.5a NPN BJT Transistor BJT s are current controlled devices, we will be using one here for the IRED input from the microcontroller in order to manipulate the Pulse cycle and the width of the pulse. The application datasheet [2] has provided with the recommended inputs in Table 1. Table 1. Recommended operating condition for IRED from datasheet [2] 13

15 2.2.6 Current Sensor Summary We will be constructing a free space current sensors which utilizes four Hall effect sensors and arrange them in the following orientation: Figure 11:Free space current sensor using four Hall effect devices[3] If we can assume our conductor (the cable that we want to measure current) is circular, infinitely long and straight, we can derive an expression for the total flux sensed by four Hall effect sensors as a function of the position of the conductor: Where x,y are the position of the conductor, and r is the radius distance from the center of the conductor to the hall sensors. When the conductor is located near the center of the four sensors, we can achieve a uniform flux response within ± 2% out to a radius of 0.4r [3]. If we move the conductor closer to on the sensors or out of the circle entirely, the response would dramatically increase and drop to zero respectively. 14

16 Figure 12:Response of four probe current sensor as function of conductor position We will be using A1301 linear Hall effect sensors that are placed on a 2.5cm diameter ring, mounted into a PCB. A hole with a diameter of 1cm will be cut out in the middle for our conductor to pass through. Figure 13: Position of the sensors on the PCB If the television wire being used has three phase current flowing through it, wrapping the current sensor above around the entire wire with all three phases will not be able to obtain accurate readings of current flowing through the three wires at once. Therefore, the main wire of the tv connecting tv to the wall plug will need to have part of its insulation removed at a small area so as to expose the 4 wires inside (three phase wires and one ground wire). The current sensor can be wrapped around any one of the three phase wires to allow our system to accurately obtain current readings. Inputs All the Hall effect sensor needs is 5V V CC. The The sensor circuit does not need another source of input. Outputs The sensor will output an analog voltage of around 50% of supply voltage. It ill have the sensitivity of 2.5 mv/g. 15

17 2.2.6a Capacitor and Resistors Figure 14: Schematics for Hall effect sensor[3] Summary We will be connecting all four Hall effect sensors through 10k Ohms resistors so that they are averaged together. The addition of the 0.1uF capacitor is included for power supply decoupling b A1301 Hall effect Sensor Summary This is a hall effect sensor with three pins: V CC, GND, and V OUT. The sensor will be used to detect the change in magnetic fields of the conducting wire through which current is flowing. The change in magnetic field will allow us to calculate the RMS current flowing through the wire. Inputs The sensor requires a supply voltage of at least 4.5V up to 6V Outputs The sensor outputs an analog signal of around 50% of the supply voltage. Figure 15: A1301 Hall effect sensor[3] 16

18 2.2.6C TPS76350 Q1 5V Voltage Regulator Summary For the hall effect sensor to operate at its optimum condition, an average input of 5V is required for the sensor. As the battery powering the circuit operates at 3.7V, a voltage regulator/boost converter will be need to step up the voltage from the battery input of 3.7V to 5V. Inputs The regulator requires an input supply voltage within a range of 2.7V to 10V. The enable pin of the voltage regulator will also be connected to a digital pin on the microcontroller to efficiently manage battery life. Outputs The regulator will output a voltage in the range of 4.875V to 5.125V, with a typical voltage output of 5V. Figure 16: TPS76350 Q1 Voltage Regulator[6] 17

19 2.3 Microcontroller and Server Flowcharts Microcontroller Flowchart Figure 17. Microcontroller Flowchart 18

20 2.3.2 Server Flowchart Figure 18. Server Flowchart 19

21 2.4 Simulations and Calculations Simulation As the 3.3V voltage regulator needs to be capable of taking an input voltage of 3.7V from our battery and give an output voltage in the range of 3.0 to 3.6V, a simulation was created in Pspice to verify this operation. Figure 19 below shows the circuit created on PSpice to simulate and Figure 20 shows the output transient wave obtained from the simulation. Figure 19. Circuit schematics of 3.3V Voltage Regulator Figure 20. Simulation plot of 3.3V Voltage Regulator As can be seen from the simulation plot above, our selected voltage regulator is successfully able to give an output in the range of 3.0 to 3.6V which will allow our microcontroller and sensors to operate correctly Calculation 2.4.2a Dust Sensor The GP2Y1010AU0F output voltage V O (monitor value) is the sum of output voltage at no dust, V OC, and output proportional to dust density Δ V. The equation and the plot were obtained from the datasheet[1] 20

22 Δ V = V O V OC Figure 21. Output voltage vs. dust density[2] The rate of increase of the output voltage is 0.5V per 0.1mg/M 3 of dust particle in the air[1]. However we need to keep in mind that way the sensor was designed, we will have a output voltage of 0.9V even in the case of no dust in the air. The following is an example plot of how the data from the sensor would be presented: Figure 22. Example of a dust density characteristics[2] 2.4.2b Current Sensor Following our design in section 2.2.6, we can derive the an expression in terms of field per unit current since all four sensors measures will be equal: 21

23 B I = μ o 2πr = 7 4π 10 (H/m) 2π m = H/m 2 (T/A) = 0.16G/A Tying the outputs together through the 10k resistors has the effect of averaging them, so the overall sensitivity of the entire sensor is the same as the average of the sensitivities of the individual Hall effect sensors, which according to the datasheets is 2.5mV/G [4]. We can then multiply the sensitivity by the I magnetic gain of the circuit to give the sensitivity V OUT V OUT I = 0.16G A 2.5mV G = 0.4mV /A I V OUT = 2.5A/mV Now, all we have to do is read the voltage output from the sensor and multiply the result to the sensitivity to obtain the current flowing through the conducting wire c Memory Storage The P1 microcontroller chip has an onboard 1 MB of system flash memory which allows it to store data being collected onboard for a limited amount of time. Our existing architecture is that the microcontroller collects sensor data every 1 hour and stores it in its onboard memory for 8 hours. After 8 hours, the WiFi module is powered on and all data stored in memory until that time is sent in one batch to the web server. This process of powering on the WiFi module, connecting it to a nearby WiFi and transferring all stored data will take approximately 2 minutes. To determine whether the microcontroller had the capacity to store sensor data for 8 hours, the bit size of each individual data string (collected every 1 hour) was calculated using an online string size calculator. In 8 hours, a total of 8 strings will be collected and stored by the microcontroller. The data representation of each string will look like the one below. XX:XX:XXXX, XX:XX, XXX.XX Month:Day:Year, Time, Sensor Data Using an online string size calculator, the above string has a length of 25 Bytes. In 8 hours, the microcontroller will collect 8 strings totaling 200 Bytes. As 1MB has

24 Bytes, we can see that the microcontroller will be able to easily store 8 strings on its onboard flash memory d Battery The battery being used for this project is a Polymer Lithium Ion Battery with a 6Ah battery life. As a battery will be connected to all sensors and the three sensors have different current draws, the battery life for each sensor will therefore vary. Table 2 below outlines the current draw of each component and the percentage of time that device will be operating in the condition. Part Operating Mode Current Percentage of Time P1 Microcontroller Sleep Mode 1mA P1 Microcontroller Active Transmission Mode 80mA V Voltage Regulator Quiescent Current 75uA 100 5V Voltage Regulator 5V Voltage Regulator Enabled Quiescent Current Shutdown Quiescent Current 140uA uA A1301 Hall Effect Sensor (Current Sensor) DS18B20 Temperature Sensor NPN Transistor (Dust Sensor) Active Mode 11mA 1.67 Active Mode 1mA 100 Active Mode 10mA 100 Table 2: Current Consumption and Time Active As all sensors have their own individual battery source, therefore, three independent equations to measure battery life of each sensor will be calculated. X: Number of hours of battery life for Current Sensor Y: Number of hours of battery life for Temperature Sensor Z: Number of hours of battery life for Dust Sensor 23

25 6000 = X * * 10 3 X * 10 3 X * * 10 3 * * 80X + 11X * 4 * X = 2796 hours = 116 days 6000 = * Y * * Y * 80 * Y + 75 * 10 3 * Y Y = 2492 hours = 103 days 6000 = * Z * * 10 3 * Z * 80 * Z + 10 * Z Z = 526 hours = 21 days A few assumptions were made when calculating the battery lives for the three sensors above. First, our current architecture requires data to be collected and stored by the microcontroller on its onboard flash memory for 8 hours, after which the WiFi module turns on for 2 mins to transmit all sensor data that it has collected in the past 8 hours to the web server. In the WiFi off stage, the P1 microcontroller is in sleep mode where the onboard code is still executing. However, in active mode, the code is executing and also transmitting data to the online web server through the WiFi module e 3.3V Voltage Regulator For the purposes of this project, the LD2951ACN 3.3G voltage regulator is used. A suggested circuit to connect the voltage regulator to Vin and its resistors and capacitor configuration to obtain an adjustable Vout can be seen in Figure 21 below. Figure 23: 3.3V Voltage Regulator Schematic 24

26 An equation to determine the value of resistors R1 and R2 for a set Vout can be seen in the equation below. V out = V ref * ( 1 + R 1/R2) Vref is given to be 1.235V and our desired Vout is 3.3V. If R2 is taken to be 10kOhms, then R1 can be calculated using the equation above to 17.35kohms. For purposes of this project, we will be using R1 to be 18 kohms. A by pass capacitor in parallel with R1 to reduce the output noise can be calculated using the equation below. C bypass = 1 /(2 * π * R 1 * 200Hz) The Cbypass value when calculated comes out to be 442uF. For the purpose of this project, we will be using a 470uF capacitor f 5V Voltage Regulator To ensure the Hall effect sensors receive a voltage of 5V, a TPS76350 Q1 Voltage regulator that outputs an average voltage of 5V will be connected to the 3.7V battery. A suggested circuit schematic to connect the voltage regulator to its input and output can be seen in Figure 24 below. Figure 24: 5V Voltage Regulator Schematic An equation to determine the value of resistors R1 and R2 for a set Vout can be seen in the equation below. V out = * V ref * ( 1 + R 1/R2) 25

27 Vref is given to be 1.192V and our desired Vout is 5V. If R2 is taken to be 169kOhms, then R1 can be calculated using the equation above to 549kohms. 2.5 Schematics On the next three pages, we have included eagle schematics for the P1 microcontroller with power supply, the current, temperature and dust sensors. 26

28 2.5.1 P1 Microcontroller with Power Supply Figure 25: Schematic for P1 Microcontroller connected to Power Supply 27

29 2.5.2 Current Sensor Figure 26. Schematic for Current Sensor connected to microcontroller 28

30 2.5.2 Dust Sensor Figure 27. Schematic for Dust Sensor connected to microcontroller 29

31 2.5.4 Temperature Sensor Figure 28. Schematic for Temperature Sensor connected to microcontroller 30

32 3 Block Level Requirements and Verification 3.1 Requirements and Verification Requirement Verification Points Temperature Sensor 1. As the temperature sensor encodes the temperature reading in binary, the sensor should be outputting a digital logic signal (High of 1 and Low of 0) Dust Sensor 1. Needs to have a sensitivity within 0.35~0.65 V/(0.1mg/m 3 ). 2. V OC needs to be 0~1.5V 3. LED terminal current I LED has to be 20mA. 4. Consumption current I CC has to be 20mA. Current Sensor 1. Needs a supply voltage of 4.5V 2. Maximum supply current of 11mA 1. Connect the VDD line of the temperature sensor to a 3.3 5V DC source being outputted from a microcontroller and connect the GND pin to ground. Place a 4.7Kohms resistor between the VDD and DQ pin (pull up resistor) and connect the DQ data pin to an oscilloscope. Adjust the scale level on the oscilloscope using its scale knobs until a logic signal with High (1) and Low (0) can be seen on the screen, with a maximum voltage of 3.3V during its high state and a voltage of 0V during its low state 1. Measure V OC by having a multimeter across Pin5 (V O ) and Pin4 (GND) in a clean room(no dust).. 2. Measure I LED by placing a multimeter in series between the BJT and Pin3. 3. Measure I CC by placing a multimeter in series right outside Pin6. 1. Measure supply voltage by placing a multimeter across Vin and GND to determine if the supply is indeed 4.5V to 6V 2. Carefully strip the insulation of the wires around only a small area to expose the three phase wires and wrap the current sensor

33 P1 Microcontroller 1. The P1 microcontroller, when supplied with DC voltage of 3.3V and an average current of 80mA powers on the status indication LED with a Cyan color indicating cloud connection 2. The P1 microcontroller is able to output a controlled pulse cycle of 10ms ± 0.1ms with a pulse width of 0.32ms ± 0.02ms, with a peak output voltage of 3.3V during its high state from the A4 analog pin to drive the LED of the Air Quality Sensor using the NPN Transistor 3. To drive the enable pin of the 5V Voltage regulator, the D3 digital pin is able to output a DC voltage of 3.3V ± 0.3V when the pin is set to high and voltage less than 0.5V when it is set to low TPS76350 Q1 Voltage Regulator 1. The voltage regulator takes in an input voltage of 3.7V to 3.9V through its VIN pin and outputs a voltage of 5V ± 2.5% with a maximum output current of 11mA around one of the three phases 3. Place a multimeter in series at Vin to determine if the current flowing through the hall effect sensors is less than 11mA. 1. Using a usb power brick, connect the usb cable to the power jack and measure the voltage being supplied to the LED. An LED with a breathing Cyan color will show a stable WiFi connection 2. Connect pin A4 to an oscilloscope and monitor the output PWM wave ensuring signal consistency with the signal requirements 3. Using a voltmeter, probe the D3 pin of the microcontroller the voltage across the pin with reference to ground during its high and low state 1. Connect a DC Power source which is outputting a voltage of V to Vin. 2. Using the schematic and resistor values of Figure 24, connect the appropriate components to the voltage regulator 3. Using a multimeter, measure the output voltage from Vout, which

34 LD 2951ACN 3.3G Voltage Regulator 2. The voltage regulator takes in an input voltage of V through its VIN pin and outputs a voltage of 3.3V ± 9 % with a maximum current of 100mA Lithium Ion Battery (6Ah) 1. The Lithium Ion Battery is outputting a minimum DC voltage of 3.7V, with a maximum of 3.9V so as to allow the circuit to operate and its maximum condition 2. The battery life of the three sensors should be as follows according to the battery calculations in a previous section a. Current Sensor PCB s battery is able to last for a maximum of 2796 hours b. Air Quality Sensor PCB s should be in the range of , at an average of 5V 4. Measure the output current from the Vout pin of the voltage regulator using a multimeter. Output current should not exceed 11mA 5. Connect a DC Power source which is outputting a voltage of V to Vin. 6. Using the schematic and resistor values of Figure 23, connect the appropriate components to the voltage regulator 7. Using a multimeter, measure the output voltage from Vout, which should be in the range of V, at an average of 3.3V 8. Measure the output current from the Vout pin of the voltage regulator using a multimeter. Output current should be in the range of 1mA to maximum 100mA 1. Use a voltmeter to measure battery voltage during data collection, data transmission and sleep modes across the positive and negative terminals of the battery. A minimum voltage of 3.7V and maximum of 3.9V should be obtained 2. Use a multi meter to measure current during data collection, data transmission and sleep mode of the microcontroller

35 battery is able to last for a maximum of 526 hours c. Temperature Sensor PCB s battery is able to last for a maximum of 2492 hours 3.2 Tolerance Analysis Table 3. Requirements and Verification Quiescent Output Voltage In the quiescent state (when magnetic field B equals 0), the output, V OUTQ, equals one half of the supply voltage, V CC, throughout the entire operating ranges of V CC and ambient temperature, TA. Due to internal component tolerances and thermal considerations, there is a tolerance on the quiescent output voltage, V OUTQ, which is a function of both V CC and T A. For purposes of specification, the quiescent output voltage as a function of temperature, V OUTQ ( TA), is defined as: where sensitivity (Sens) is in mv/g, and the result is the device equivalent accuracy, in gauss (G), applicable over the entire operating temperature range Sensitivity The presence of a south polarity (+B) magnetic field, perpendicular to the branded face of the device package, increases the output voltage, V OUT, in proportion to the magnetic field applied, from V OUTQ toward the V CC rail. Conversely, the application of a north polarity ( B) magnetic field, in the same orientation, proportionally decreases the output voltage from its quiescent value. This proportionality is specified as the magnetic sensitivity of the device and is defined as: 34

36 The stability of the device magnetic sensitivity as a function of ambient temperature, ΔSensΔ TA (%) is defined as: 3.3 Safety and Ethical Considerations Ethical Considerations Point nine of the IEEE code of ethics states that we commit ourselves to avoid injuring others, their property, reputation, or employment by false or malicious action. If we are not careful in our setup, a hacker could intercept sensor traffic to read and place false values into our database. The hotel management may then believe their rooms are in good condition, when in reality they are not and that will have an effect on their reputation. The quality of the rooms is information that should be private to the hotel and only released to others as they see fit Safety Considerations Concerns about our project are primarily within the realm of information security. The sensors we build should not cause harm to others so long as the appropriate levels of current and voltage are applied to them, because if they are overcharged it will likely lead to damage of the sensor. 35

37 4 Cost and Schedule 4.1 Cost Analysis Labor Costs Name Hourly Rate Total Hours Invested Total=Hourly Rate x 2.5 x Total Hours Invested Milan $ $ Murtaza $ $ Willie $ $ Total $ $ Part Costs Item w/ Part Number Quantity Cost P1 WiFi Enabled Microcontroller 3 $36 Temperature Sensor (DS18B20) 1 $9.95 Dust Sensor (GP2Y1010AU0F) 1 $ Ah Lithium Ion battery(prt 08484) Voltage Regulator (LP2951ACN 3.3G) NPN BJT Transistor (511 TIP41C) Voltage Regulator (TPS76350 Q1) 3 $ $ $ $0.97 Wires N/A $1.62 Resistors N/A $7.95 A1301 Hall Effect Sensors 4 $7.32 Diodes(1N4148) N/A $ uf Capacitor 13 $

38 0.1 uf Capacitor 15 $ uf Capacitor 1 $ uf Capacitor 3 $ uf Capacitor 1 $0.98 Total $ Total Section Total Labor $ Parts $ Grand Total $

39 4.2 Tasks Schedule Week of Task Person 10/5 Build web server and database Milan Catalogue and order required parts Setup microcontroller programming environment Murtaza Willie 10/12 Program microcontroller for current sensor Milan Create circuit for P1 microcontroller and voltage regulator with battery on breadboard Create and test circuit for current sensor on breadboard with P1 microcontroller Murtaza Willie 10/19 Program microcontroller for dust sensor Milan Create Eagle Schematic of PCB for all sensors Create and test circuit for dust sensor on breadboard by integrating with P1 microcontroller Murtaza Willie 10/26 Program microcontroller for temperature sensor Milan Create and test circuit for temperature sensor on breadboard with P1 microcontroller Revise PCB design and place order for PCB 11/2 Debug and revise server and microcontroller programming bugs Solder components onto PCB and test device operation Solder components onto PCB and test device operation 11/9 Program basic user interface to view live sensor readings on a web link Conduct endurance tests of PCB and active debugging Start creation of presentation material and final document Murtaza Willie Milan Murtaza Willie Milan Murtaza Willie 38

40 11/16 Finalize Demo Milan Refine Presentation Populate Final Paper Murtaza Willie 11/23 Thanksgiving Break All 11/30 Finalize Presentation Milan Finalize Presentation and populate Final Paper Finalize Final Paper Murtaza Willie 12/7 Submit Final paper and conduct Lab checkout All 39

41 5. References 1. GP2Y1010AUoF Datasheet, Sheet No: E4 A01501EN Date Dec Application note of Sharp dust sensor GP2Y1010AU0F, Sheet No.: OP13024EN world.com/products/device/lineup/data/pdf/datasheet/gp2y1010 au_appl_e.pdf 3. Hall Effect Sensors: Theory and Application, Second Edition by Edward Ramsden. 2006, Elsevier. 4. A1301 Hall effect sensor datasheet. Allegro A1301 DS, Rev 17 pdf/view/120794/allegro/a1301.html 5. P1 Datasheet, Particle, accessed 9/25/ datasheet/ 6. TPS Q1 Datasheet, accessed 10/9/ q1.pdf 40