DesignReviewNew
Vehicle Monitoring System
ECE 445 Project Design Review
TA: Cara Yang
Ishan Ahuja
Caleb Perkinson
Samuel Utomi
February 29, 2016
Contents
1.
2.
3.
4.
5.
Introduction ...............................................................................................................................3
1.1.
Statement of Purpose ................................................................................................................... 3
1.2.
Objectives...................................................................................................................................... 3
1.2.1.
Benefits and Features ........................................................................................................... 3
1.2.2.
Goals and Functions .............................................................................................................. 3
Design ........................................................................................................................................4
2.1.
Block Diagrams .............................................................................................................................. 4
2.2.
Block Descriptions ......................................................................................................................... 5
2.2.1.
Power Circuits ....................................................................................................................... 5
2.2.2.
Microcontroller (Texas Instruments CC3200) ....................................................................... 5
2.2.3.
GPS Unit ................................................................................................................................ 5
2.2.4.
Accelerometer....................................................................................................................... 6
2.2.5.
Gyroscope ............................................................................................................................. 6
2.2.6.
OBD-II Transceiver ................................................................................................................ 6
2.2.7.
Wi-Fi Transceiver................................................................................................................... 6
2.2.8.
Battery................................................................................................................................... 7
2.2.9.
Memory................................................................................................................................. 7
2.3.
Software Flowchart ....................................................................................................................... 8
2.4.
Schematics .................................................................................................................................... 9
2.5.
Simulations and Calculations ...................................................................................................... 15
2.5.1.
Buck Converter Calculation ................................................................................................. 15
2.5.2.
Buck Converter Schematic ................................................................................................. 16
2.5.3.
Buck Converter Simulations ................................................................................................ 16
Requirements and Verification .................................................................................................. 19
3.1.
Requirements and Verification ................................................................................................... 19
3.2.
Point Allocation .............................................................................. Error! Bookmark not defined.
3.3.
Tolerance Analysis....................................................................................................................... 24
Ethics and Safety ...................................................................................................................... 25
4.1.
Ethics ........................................................................................................................................... 25
4.2.
Safety .......................................................................................................................................... 26
Cost and Schedule .................................................................................................................... 27
5.1.
Cost Analysis ............................................................................................................................... 27
1
6.
5.1.1.
Parts .................................................................................................................................... 27
5.1.2.
Labor ................................................................................................................................... 27
5.2.
Grand Total ................................................................................................................................. 27
5.3.
Schedule ...................................................................................................................................... 28
References ............................................................................................................................... 29
List of Figures
Figure 1: System High-Level Operation Diagram .......................................................................................... 4
Figure 2: Device Block Diagram..................................................................................................................... 4
Figure 3: Device Software Diagram............................................................................................................... 8
Figure 4. Main Circuit Schematic .................................................................................................................. 9
Figure 5. Microcontroller Circuit ................................................................................................................. 10
Figure 6. CAN Bus transceiver circuit .......................................................................................................... 11
Figure 7. J1850 and ISO Bus transceiver circuits ......................................................................................... 12
Figure 8. Power Circuits .............................................................................................................................. 13
Figure 9. OBD interpreter circuit................................................................................................................. 14
Figure 10: Buck Converter Schematic [5].................................................................................................... 16
Figure 11: Output Voltage and Battery Voltage While Battery Charging ................................................... 16
Figure 12: Battery Charging Current ........................................................................................................... 17
Figure 13: Output Current Ripple ............................................................................................................... 17
Figure 14: Output Voltage, Battery Voltage and Battery Current in Overvoltage ...................................... 18
List of Tables
Table 1: Requirements and Verification Table............................................................................................ 19
Table 2: Point Allocation ................................................................................ Error! Bookmark not defined.
Table 3: Major Component Load Summary ................................................................................................ 24
2
1. Introduction
1.1. Statement of Purpose
The purpose of our product is to allow for constant monitoring of characteristic data about a
vehicle and make it accessible in an easy way. This monitoring will allow managers of large fleets
to easily keep track of their vehicles while also being able to quantify their driver’s safe driving
abilities. The product will allow for a much leaner fleet through increasing productivity by making
it simple to utilize fixed resources to their maximum capacity. It will also help improve the image
of the organization by promoting safe driving.
1.2. Objectives
1.2.1. Benefits and Features




Encourage safe and efficient driving behavior in fleet drivers
Improve fleet productivity
Keep drivers accountable
Make fleet data easy to view
1.2.2. Goals and Functions




Monitor:
o Fuel levels (from OBD II messages)
o Speed (from OBD II messages)
o Acceleration & breaking (from accelerometer and gyroscope)
o G-force while turning (from accelerometer and gyroscope)
o Location (GPS) (from GPS chip)
o Vehicle alerts (from OBD II messages)
o Miles driven (from OBD II messages and GPS)
Access recorded data through online web page
Provide derived metrics such as
o Miles driver over speed limit
o Driver fuel efficiency
o Quick or unsafe turning
o Ignoring vehicle error messages
No driver intervention necessary once plugged in
3
2. Design
2.1. Block Diagrams
Figure 1: System High-Level Operation Diagram
Figure 2: Device Block Diagram
4
2.2. Block Descriptions
2.2.1. Power Circuits (Buck Converter)
Inputs: +12V from car, PWM signal from microcontroller
Output: +5V
The OBD port on all vehicles have a 12V rail. Since our components primarily operate on 3.3V,
refer to Table 1 for voltage requirements, the 12V must be stepped down. The 12V will be
stepped down using a Buck converter, shown in Section 5.2, but will first be passed through a
filter to give a clean 12V supply. The device will operate in multiple states. When the vehicle is
on, thus 12V is available, the device battery will charge and the circuitry will be powered directly
from the buck converter. When the vehicle is off, the vehicle’s battery voltage is not available.
Therefore, the device battery will become a source for the rest of the circuitry. Protection
circuitry is required so that the battery is kept in safe operating conditions at all times.
Thermistors and voltage sensing will be employed to prevent over-heating and over-charging.
To prevent over-charging, the voltage across the battery will be monitored and fed into an ADC
pin on the microcontroller. When the voltage is too great the FET will be opened and charging
of the battery will be prevented. To provide power to the microcontroller, sensors, and
telemetry module an LDO regulator will convert the 3.7V output from the battery to 3.3V.
2.2.2. Microcontroller (Texas Instruments CC3200)
Inputs: +3.3V power input, Gyroscope and Accelerometer Data, OBD messages, Battery
Temperature Measurement, Battery Voltage Measurement, GPS data, Wi-Fi messages, Push
Buttons
Outputs: Wi-Fi messages, PWM for Buck converter, Battery switch control
The microcontroller used for this project is the Texas Instruments CC3200. The CC3200 was
chosen because of its low-power capabilities and its integrated Wi-Fi processor. This device will
serve many functions. It will poll the accelerometer, gyroscope, and OBD decoder using I2C, SPI,
and UART protocols, respectively. This data will have some processing done on it and then it will
be sent to the remote database, to be discussed late, where it can be accessed by the user.
Since Wi-Fi is the communication protocol of choice, bandwidth should not be an issue when
sending raw data. This device will also monitor the voltage and temperature on the battery
using GPIO pins that can be configured as ADCs. Should the battery get too close to a dangerous
condition, the microcontroller will remove it from the circuit using the switching FET.
2.2.3. GPS Unit
Input: +3.3V power input
Output: GPS data
This module will collect GPS data on the car’s location. Having access to this data allows fleet
managers to track their vehicles, police to recover stolen cars, as well as countless number of
other applications yet to be thought of. While the car is on, the microcontroller will request the
location from the GPS unit at a regular interval and then transmit it to the remote server. When
the car is off, the microcontroller will set the GPS unit into low power mode and will only poll
the GPS when the location is requested by a user from the user interface.
5
2.2.4. Accelerometer
Inputs: +3.3V power input
Outputs: Accelerometer Data
The accelerometer used for this project will be the MMA8653FC manufacture by Freescale. This
is a low-power device that talks with the microcontroller over I2C. The device is extremely
flexible allowing for programmable interrupts, which will be used to detect when the vehicle is
off and suddenly moved, potentially indicating that it is being towed. The device works on 3.3V
and has a 10-bit digital output. The information obtained from this device, in conjunction with
the gyroscope, will be used to determine if the user is accelerating too quickly or making
dangerous stops or if it has been involved in an accident. The microcontroller will record this
information and send the information in the next data packet over Wi-Fi.
2.2.5. Gyroscope
Inputs: +3.3V power input
Outputs: Gyroscope Data
The gyroscope used in this project is the FXAS21002C manufacture by Freescale. This device
communicates using SPI and has 16 bits of resolution measuring angular rates up to 2000°/s.
Interrupts can be configured to generate when a threshold angular acceleration is reached.
Using this device will allow the microcontroller to determine if the vehicle is turning at speeds
considered unsafe.
2.2.6. OBD-II Transceiver
Inputs: +3.3V power input, +5V for Bus Transceiver Circuits, J1850 messages, CAN messages, ISO
messages
Output: OBD messages
OBD-II (On-Board Diagnostic II) is a protocol which most vehicles use to relay information about
the car to mechanics and others that would need the information. These messages are available
from the OBD port on vehicles. The device will attach to this port and will use the OBD-II
transceiver module to interpret the messages. The device used in this project is the STN1110. It
is able to interpret most J1850, ISO and CAN messages that come across the OBD port. This
device converts those messages into a UART message that is sent to the microcontroller.
2.2.7. Wi-Fi Transceiver
Input: +3.3V power input, Messages to Transmit
Output: Received Messages
Wi-Fi network processing is integrated into the CC3200 microcontroller. The purpose of this
module is to demonstrate the hardware backend of the Wi-Fi network. An SMT antenna will be
used on the board to implement the hardware stack. This module will serve as the
communication point between the server and the Driver Monitoring System board. Since a
cellular 3G/4G connection would be too expensive we will set up a hotspot in the vehicle to give
the Wi-Fi module a direct connection to the server.
6
2.2.8. Battery
Input: Regulated voltage for charging
Output: +3.7V
The purpose of the battery is to provide the device with enough power to send emergency
messages when the vehicle is off and the 12V is not supplied to the device. Only certain devices,
like the Wi-Fi module, GPS and microcontroller, will be on when the vehicle is powered off, so as
to not waste power. Such use-cases would include a collision where the car loses power or a car
is being towed and would send an alert to the owner.
2.2.9. Memory
Input: +3.3 power input
There will be a small amount of cache memory to buffer packets being sent to the telemetry
module. This is to alleviate potentially bad connections where the telemetry module is not able
to send packets. The microcontroller will buffer messages until it is able to send again. Three
attempts will be made to transmit the message before it is cleared from memory.
7
2.3. Software Flowchart
Figure 3: Device Software Diagram
8
2.4. Schematics
Figure 4. Main Circuit Schematic
Figure 5. Microcontroller Circuit
10
Figure 6. CAN Bus transceiver circuit
11
Figure 7. J1850 and ISO Bus transceiver circuits
12
Figure 8. Power Circuits
13
Figure 9. OBD interpreter circuit
14
2.5. Simulations and Calculations
2.5.1. Buck Converter Calculation
Since the supplied voltage from the car battery, made available to us through the OBD II port, is
12 V, we have decided to use a buck converter to drop the voltage from 12V to 5.3V, which is
the voltage that we want to charge our battery at. The acceptable range in this voltage is ±1%.
Below are our calculations for the parameters defining the components of our converter. [2]
Design Choices
𝑂𝑢𝑡𝑝𝑢𝑡 𝑉𝑜𝑙𝑡𝑎𝑔𝑒 𝑆𝑝𝑒𝑐. = 5.3𝑉 ± 1%
𝑆𝑤𝑖𝑡𝑐ℎ𝑖𝑛𝑔 𝐹𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦 = 150𝑘𝐻𝑧
𝐶𝑢𝑟𝑟𝑒𝑛𝑡 𝑅𝑖𝑝𝑝𝑙𝑒 = 100𝑚𝐴
Calculations
𝑀𝑎𝑥 𝑉𝑜𝑙𝑡𝑎𝑔𝑒 𝑅𝑖𝑝𝑝𝑙𝑒 = 1% ∗ 5.3 = 106𝑚𝑉
𝑉𝑜𝑢𝑡 = 𝐷 ∗ 𝑉𝑖𝑛 [D is the duty ratio]
𝑉𝑜𝑢𝑡 5.3
=
= 0.45
𝑉𝑖𝑛
12
𝐷=
𝐼𝑛𝑑𝑢𝑐𝑡𝑜𝑟 𝑉𝑜𝑙𝑡𝑎𝑔𝑒 = 𝑉𝐿 = 𝑉𝑖𝑛 − 𝑉𝑜𝑢𝑡 = 12 − 5.3 = 6.7𝑉
𝑉𝐿 = 𝐿
𝑑𝑖
∆𝑖
=𝐿
𝑑𝑡
∆𝑡
1
∆𝑡 = 𝐷𝑇 = 𝐷 𝐹
𝑠𝑤
𝐿=
𝑉𝐿 ∗ ∆𝑡
= 200𝜇𝐻
∆𝑖
𝐶𝑜𝑢𝑡,𝑚𝑖𝑛 = 8∗𝐹
∆𝐼𝐿
𝑠𝑤 ∗𝑉𝑟𝑖𝑝𝑝𝑙𝑒
= 0.79𝜇𝐹 [7]
Note that the output capacitance calculated is the minimum required value and does not
put into account the equivalent series resistance of the capacitor. For our circuit, we will
be using a much larger capacitor to account for that and have improved performance.
2.5.2. Buck Converter Schematic
Figure 10: Buck Converter Schematic [5]
2.5.3. Buck Converter Simulations
Figure 11: Output Voltage and Battery Voltage While Battery Charging
16
Figure 12: Battery Charging Current
Figure 13: Output Current Ripple
17
Figure 14: Output Voltage, Battery Voltage and Battery Current in Overvoltage
18
3. Requirements and Verification
3.1. Requirements and Verification
Table 1: Requirements and Verification Table
Module
Requirements
Verification
Points
Accelerometer
1) The accelerometer must be
calibrated to measure
acceleration on the plane
parallel to the road.
1)
5
2) Sensor should be able to
detect acceleration within 1g
with an error of ±5%.
3) Sensitivity is maintained
over the temperature range
-25°C to 50°C.
(a) Power Microcontroller
(b) Initiate calibration routine for
accelerometer
(c) Read the 3 axes of the
accelerometer and ensure the 2
axes that create the measurement
plane read nearly 0 acceleration
(therefore the axis orthogonal to
the earth will have 1g)
2)
(a) Power microcontroller to 3.3V
(b) Connect accelerometer to
microcontroller
(c) First record output data when
there is no motion to detect bias
error, then apply force to the
device with hand and ensure
output data changes
3)
(a) Using a heat gun, increase the
temperature of the device to high
end of the temperature.
(b) While the device is stationary,
measure changes in readings as
temperature is increased by 20°C
(within the required rating
parameters) to find how much the
reading drifts as a temperature
changes.
19
Gyro Sensor
1) Gyro bias error ≤ 1°/sec
1)
2) Gyro lag ≤ 5°/sec when
angular velocity greater than
45°/sec
(a) Power microcontroller to 3.3V
5
(b) Connect gyro sensor to
microcontroller
(c) Record output data during no
motion and ensure minimal error
2)
(a) Power microcontroller to 3.3V
(b) Connect gyro sensor to
microcontroller
(c) Using a protractor, turn the gyro
sensor by 45 degrees in a second
and observe output measured by
sensor
Microcontroller Digital Output
1)
Digital 0 corresponds to Vout
0.5V
(a) Power Microcontroller with
3.3V
Digital 1 corresponds to Vout
3V
(b) Program all pins to output
Digital 0
(c) Probe pins to verify Vout 0.5V
2)
(a) Power Microcontroller with
3.3V
(b) Program all pins to output
Digital 1
(c) Probe pins to verify Vout 3V
20
5
Digital Input
1)
Digital 0 corresponds to Vin
0.5V
(a) Power Microcontroller with
3.3V
Digital 1 corresponds to Vin
3V
(b) Set pins to input mode and print
their value to the serial port
(c) Apply 0.2V to each pin to ensure
proper reading
2)
(a) Power Microcontroller with
3.3V
(b) Set pins to input mode and print
their value to the serial port
(c) Apply 3V to each pin to ensure
proper reading
Analog Digital Converter
1)
1) Can read analog signals
from 0V to 5V ±5%
(a) Hook ADC to power supply
2) Able to reject greater than
10Hz
(b) Enable rated current on the
supply to prevent damaging the
microcontroller
(c) Print the value of the ADC to the
serial port
(d) Sweep the voltage from 0 to 5V
and verify proper quantization
2)
(a) Hook ADC to power supply
(b) Apply 10Hz signal and verify
that it doesn’t read the signal
21
Low Power Consumption
1)
Iavg≤ 500uA at 3.3V
(a) Power Microcontroller with
3.3V
(b) Place ammeter in series with
supply
(c) Put microcontroller in low
power mode.
(d) Ensure Iavg ≤ 500uA
OBD-II
Transceiver
module
1) Should be able to decode
messages that conform to the
OBD-II standard
1)
Wifi module
1) Should conform to the
802.11b/g/n wireless standard
1)
2) Minimum acceptable signal
strength of -70dBm to
transmit data
10
(a) Connect to the car and verify
that OBD messages are being
received correctly by comparing
messages read by commercial OBD
reader
(a) Power microcontroller to 3.3V
(b) Connect module to
microcontroller
(c) Send a message from the
microcontroller and verify the
message has been received by the
server within 5 seconds
2)
(a) Use phone as a hotspot to
connect board to Wi-Fi
(b) Ensure the phone is within 2m
of the device and has a 3g
connection of at least 3 out of 5
bars.
22
5
GPS module
1) Should be accurate within
5m
1)
5
(a) Power microcontroller to 3.3V
(b) Connect module to
microcontroller
(c) Compare coordinates received
on server to google GPS location of
phone
Buck converter
charging circuit
1) 5.3V output voltage ±1%
1)
(a) Attach 100Ω resistor bank as
load for buck converter
(b) Connect oscilloscope probes at
both ends of the load and measure
voltage ripple
Battery
1) Should be able to last 4
days when discharging
1)
(a) Using power supply, charge
2) Can handle charging current battery to max voltage
up to 1A and stay below rated
(b) Attach to a rated load
temperature of 50°C [3][4]
(c) Let it discharge for 4 hours
(d) Ensure it has more than 95% of
its charge left
2)
(a) Use DC supply and inject 1A of
current
(b) Measure temperature using
thermistor and ensure it does not
go above 40°C after an hour of
charging
23
15
Linear
regulator
circuit
1) Output voltage is 3.3V ±1%
with a total current
consumption of up to
400mA
1)
(a) Use DC supply with 12V input
(b) Attach multimeter probes
across 100Ω load
(c) Ensure output voltage is within
bounds
Storage
module
1) Memory capacity of at least
64kbits
1)
(a) Power microcontroller to 3.3V
(b) Connect module to
microcontroller
(c) Send bit message from
microcontroller to storage module
3.2. Tolerance Analysis
Table 2: Major Component Load Summary
Load
Voltage
+3.3V
Current
(Active
Mode)
194 mA
Current
(Sleep
Mode)
12.2 mA
Power
Consumption
(Active Mode)
0.64W
Power
Consumption
(Sleep Mode)
0.04W
Microcontroller
+ WiFi
Accelerometer
Gyroscope
OBD
Transceiver
GPS Module
+3.3V
+3.3V
+3.3V
2.7 mA
27 µA
68 mA
2.8 µA
1.4 µA
-
8.9mW
89.1 µW
0.224W
0.24µW
4.62 µW
0
+1.8V
47mA
20 µA
84.6 mW
36 µW
Access to power is essential to our project’s operation. This is true both when the vehicle is
operational and when it isn’t. When the vehicle is not on, a battery is required to allow for our
device to function for a set period of time. The device will send out a GPS location ping to the server
at regular intervals. Using the load characteristics listed in table 1, we estimate that we will require
23.5mA current on average when using battery power. This was calculated as follows:
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑡𝑟𝑎𝑛𝑠𝑚𝑖𝑡𝑠 𝑝𝑒𝑟 ℎ𝑜𝑢𝑟 = 2
𝐶𝑢𝑟𝑟𝑒𝑛𝑡 𝐶𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 𝑤ℎ𝑒𝑛 𝑡𝑟𝑎𝑛𝑠𝑚𝑖𝑡𝑡𝑖𝑛𝑔 = 194 + 2.7 + 0.027 + 68 + 47 = 311.7𝑚𝐴
24
𝐶𝑢𝑟𝑟𝑒𝑛𝑡 𝑐𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 𝑖𝑛 𝑠𝑙𝑒𝑒𝑝 𝑚𝑜𝑑𝑒 = 12.2 + 0.0028 + 0.0014 + 0.020 = 12.22𝑚𝐴
2
58
𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝑐𝑢𝑟𝑟𝑒𝑛𝑡 𝑐𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 = ( ∗ 311.7) + ( ∗ 12.22) = 22.20𝑚𝐴
60
60
Our requirement is that the device be able to function for at least 4 days after the vehicle has been
turned off. To meet this requirement, we will need a battery capacity as follows.
22.20𝑚𝐴 ∗ 96 ℎ𝑜𝑢𝑟𝑠 = 2131.6𝑚𝐴ℎ
This is the minimum capacity which the battery will need to satisfy, and we would ideally prefer to
use a battery which has much greater capacity to allow for longer battery life. To measure and verify
the capacity of the battery, we will discharge it at a rate of 1 C, where C is the rated current draw for
discharge of the course of 30 minutes. We will then recharge the battery so as to be able to ensure
that it can be brought back up to full charge again.
When the device is not running on battery power, the consumption will be as follows.
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑡𝑟𝑎𝑛𝑠𝑚𝑖𝑡𝑠 𝑝𝑒𝑟 ℎ𝑜𝑢𝑟 = 10
𝐶𝑢𝑟𝑟𝑒𝑛𝑡 𝐶𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 𝑤ℎ𝑒𝑛 𝑡𝑟𝑎𝑛𝑠𝑚𝑖𝑡𝑡𝑖𝑛𝑔 = 194 + 2.7 + 0.027 + 68 + 47 = 311.7𝑚𝐴
𝐶𝑢𝑟𝑟𝑒𝑛𝑡 𝑐𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 𝑖𝑛 𝑠𝑙𝑒𝑒𝑝 𝑚𝑜𝑑𝑒 = 12.2 + 0.0028 + 0.0014 + 0.020 = 12.22𝑚𝐴
10
50
𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝑐𝑢𝑟𝑟𝑒𝑛𝑡 𝑐𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 = ( ∗ 311.7) + ( ∗ 12.22) = 62.13𝑚𝐴
60
60
Since the device will be powered by the car battery which on average have a capacity greater than
50Ah, we don’t expect our device to experience any issues in functionality, or interfere with the
regular functionality of the vehicle.
Another aspect of operation which using a battery will affect is the functioning temperature range.
Since batteries are not very resilient to extreme temperatures, we must ensure that the battery can
operate at the extremes of its temperature range. To validate this, the device must provide rated
voltage and current at 200F and 1000F. A heat gun and thermometer can be used to bring the
temperature of the battery up to 1000F and the battery will be loaded using a resistor bank and it
will be metered to verify the rated specs are met. The same can be done in the converse by placing
the battery in the freezer to bring it to 200F. This will ensure that the battery doesn’t get damaged
and will not harm the other components.
4. Ethics and Safety
4.1. Ethics
Our team and project will strive to comply with the following stipulations in the IEEE Code of Ethics
[6]
1) We accept responsibility in making decisions consistent with the safety, health, and welfare of
the public, and to disclose promptly factors that might endanger the public or the environment;
2) to be honest and realistic in stating claims or estimates based on available data;
3) to reject bribery in all its forms;
4) to maintain and improve our technical competence and to undertake technological tasks for
others only if qualified by training or experience, or after full disclosure of pertinent limitations;
25
5) to seek, accept, and offer honest criticism of technical work, to acknowledge and correct errors,
and to credit properly the contributions of others;
6) to treat fairly all persons and to not engage in acts of discrimination based on race, religion,
gender, disability, age, national origin, sexual orientation, gender identity, or gender expression;
7) to avoid injuring others, their property, reputation, or employment by false or malicious action;
8) to assist colleagues and co-workers in their professional development and to support them in
following this code of ethics.
4.2. Safety
Since our device will have a very low power consumption, there are very few components that will
pose a threat to the user’s safety. One major concern is that we are using a primary lithium ion
battery to power the device when there is no vehicle power, we need to take safety precautions to
avoid damage to the device. The two types of hazards relevant to using rechargeable lithium ion
batteries are chemical and electrical. [1]


Chemical Hazards
o Spillage
 To prevent rupturing of the battery causing a spill, we will ensure that the
battery is sufficiently encased and isolated from user intervention.
o Gas Emission
 Since our device is not rated to function in the temperature range where
gas emissions would be a possible (i.e. greater than 180oC), this is not a
concern.
Electrical Hazards
o Joule Effect
 Current flowing through the battery during charging/discharging will heat
the device. To prevent this, we will restrict battery charging and discharging
to a safe range based on the battery specification.
 We will ensure that the current drawn is within an acceptable range, by
thoroughly considering any possibilities of short circuits.
o International Battery Standards
 The battery we use will be will comply with regulatory standards.
o Damage due to overcharging
 Overcharging will be prevented by monitoring battery voltage.
o Damage due to heat
 Ambient temperature will be monitored, and battery will be cutoff in the
case of temperature reaching unsafe levels.
To ensure that all relevant safety requirements met, all team members will train on battery safety
though reading IEEE Standard for Rechargeable Batteries for Cellular Telephones, in addition to the
lab safety and electrical safety quizzes taken online for the course.
26
5. Cost and Schedule
5.1. Cost Analysis
5.1.1. Parts
Item
Microcontroller
Part Number
CC3200
GPS Chip
Accelerometer
Gyroscope
PCB
OBDII Connector
Resistors &
Capacitors
Device Housing
Antenna
RF filter
Memory
Oscillator
Mosfet
Miscellaneous
Total
M10478-A1
MMA8653FCR1
FXAS21002CQR1CT-ND
Bay Area Circuits
STN1110
SMT/SMD 0805 Resistor and
Capacitor Book - 3725 pieces
3D printed
AH316M245001-T
DEA202450BT
M25PX80-VMN6TP
FA-20H
IRF530N
Vendor
Texas
Instruments
ANTENOVA
Freescale
Freescale
ScanTool.net
Taiyo Yuden
Taiyo Yuden
Micron Tech
Epson
Jameco
Quantity
1
Cost
$18.08
1
1
1
1
1
10-40
$15.15
$1.09
$3.56
$30
$9.99
$20
1
1
$10
$1.95
$0.51
$0.86
$0.82
$0.95
$15
$127.96
-
5.1.2. Labor
Name
Caleb Perkinson
Samuel Utomi
Ishan Ahuja
Total
Hourly Rate
$35
$35
$35
$105
Hours Invested
250
250
250
750
5.2. Grand Total
Section
Labor
Parts
Total
Cost
$65,625
$127.96
$65,752.96
27
Total*2.5
$21,875
$21,875
$21,875
$65,625
5.3. Schedule
Week
2/8
Task
Finalize and format proposal
Prepare mock design review
2/15
Research and select chips to be used
Research telemetry functionality
Research programming microcontroller
Order parts, request free samples
Prepare design review documents
Start designing board
Start setting up server & database
Build test circuit on breadboard
2/22
2/29
3/7
3/14
3/21
(SB)
3/28
4/4
4/11
4/18
Start writing telemetry code
Compile design review documents
Run initial tests for telemetry
Run initial tests for accelerometer and gyroscope
Finalize circuit and order SMT parts and PCB
Finish online database and server setup
Solder chips to PCB
Finalize simple access page
Test final unit in car with live data collection & squash bugs
in software
Test final unit in car with live data collection & squash bugs
in logic
Test final unit in car with live data collection & squash bugs
in power circuits
Finish final revision of board
Finalize software
Submit updated R&V table
Run more live tests
Prepare mock demo
Perform mock demo
Prepare for final presentation & incorporate feedback from
mock demo
Start final paper and assign work
28
Responsibility
Ishan
Sammy &
Caleb
Ishan
Caleb
Sammy
Ishan
Sammy
Caleb
Ishan
Sammy &
Ishan
Caleb
Ishan
Caleb
Sammy
Ishan
Sammy &
Ishan
Caleb
Ishan
Ishan
Caleb
Sammy
Caleb
Ishan
Sammy
Sammy &
Caleb
Ishan
All three
Caleb &
Sammy
Ishan
4/25
Mock final presentation
5/2
Compile first draft of final paper
Finalize presentation
Lab checkout and finalize final paper
Caleb &
Sammy
Ishan
Caleb & Ishan
Sammy
6. References
[1] Safety of Lithium Ion Batteries [Online], Available:
http://www.rechargebatteries.org/wp-content/uploads/2013/07/Li-ion-safety-July-9-2013-Recharge.pdf
[2] Philip T. Krein, Elements of Power Electronics
[3] Design Trade-offs for Switch-Mode Battery Chargers [Online], Available:
http://www.ti.com/lit/ml/slyp089/slyp089.pdf
[4] A Guide to Battery Charging [Online], Available:
http://www.operatingtech.com/lib/pdf/A%20Guide%20to%20battery%20Charging.pdf
[5] LTSpice IV Getting Started Guide [Online], Available:
http://cds.linear.com/docs/en/software-and-simulation/LTspiceGettingStartedGuide.pdf
[6] IEEE Code of Ethics, Retrieved February 2016, Available:
http://www.ieee.org/about/corporate/governance/p7-8.html
[7] Basic Calculation of Buck Converter Power Stage
http://www.ti.com/lit/an/slva477b/slva477b.pdf
29
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