Bradley University Electrical Engineering Department

SAE Formula CarData Acquisition & Display System

April 9, 2015

Advisor : Professor Steven Gutschlag

Ahmed Albitar John Gertie

Justin Ibarra Sean Lenz

Agenda• Problem statement

• Background

• System block diagram

• Division of labor

• Project non-functional requirements

• Project functional requirements

• Discussion of individual contributions

• System test results

• Summary & conclusion2

3

Problem Statement

Every year the Mechanical Engineering department at Bradley University designs and constructs a formula racing car. Past performances have proven to be inconsistent due to engine failures and structural breakdowns. To improve future performance, an advanced data acquisition system will be employed to indicate problems before a failure occurs. Unlike the existing system, data will be monitored by both the driver and the crew. A touch screen mounted in the vehicle will display data and warning signals to the driver. The same data will also be transmitted to a computer, where it will be recorded for diagnostic evaluations. Multiple indicators will be used to warn the driver and crew if data readings exceed a safe limit.This system will provide the necessary information to optimize the formula cars performance, giving Bradley’s mechanical engineering department an edge over the competition.

Problem Description

• Acquire 5 Key data values from SAE Formula Car

• RPM

• Speed

• Oil Pressure

• Water Temperature

• Battery Voltage

• Aggressive Notification system to alert driver if data exceeds threshold values

• Multi-mode touch screen display

• Wireless transmission of data to off-track computer

• Data Logger 4

5

Background

• Design goals

• Aesthetically pleasing

• Economically viable

• Race ready performance

• User friendly for all levels

• '07-'10 Honda CBR600RR engine

• Total budget of $10,000

System Block Diagram

Sensors

Microcontroller

(ATmega128)

Amulet LCD

Wireless Transceive

r

UART

RS-232

Laptop(LabVIEW

GUI)UART

5V Power Supply

6

Division of Labor

• Ahmed

• Sensor selection & interfacing

• Justin

• Amulet display

• Justin & John

• Interface microcontroller with HyperTerminal

• Test microcontroller with simulated sensor data

• Interface microcontroller with LabVIEW

• Sean

• Prepared LabVIEW to receive wireless data

• Interface microcontroller with Amulet

• Setup external power supplies for the microcontroller, Amulet, and Op-Amps7

System Block Diagram

Sensors

Microcontroller

(ATmega128)

Amulet LCD

Wireless Transceive

r

UART

RS-232

Laptop(LabVIEW

GUI)

UART

5V Power Supply

Ahmed

Sean

John & Justin

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Sean

Project Non-functional Requirements

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Project Functional Requirements

11

Ahmed's Agenda

• Subsystem block diagram

• Pressure and Temperature Sensor Circuitry

• Project functional requirement and specification

• Sensors

• Test result

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Subsystem Block Diagram

Engine12V

ATmega128

Temperature Sensor

Pressure Sensor

RPM Sensor

Velocity Sensor

Voltage Measurement

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Pressure and Temperature Sensor Circuitry

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Functional Requirements and specification

• 12 volts from the car's battery

• Water temperature measured by a temperature sensor

• Oil pressure measured by a pressure sensor

• Velocity and RPM measured by a speed sensor

• Data acquisition maximum error of 5%

• Sensors compatible with engine

15

Temperature Sensor

• ProSense TTD25N-20-0300F-H

• Analog output: 4 to 20mA

• Operating Voltage: 10 to 30VDC

• Temperature range: 0-300 F

• ¼ NPT

• Cable : CD12L-0B-020-A0

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Pressure Sensor

• ProSense PTD25-20-0100H

• Analog output: 4 to 20mA

• Operating Voltage: 9.6 to 32VDC

• PSI range: 0 to 100

• ¼ NPT

• Cable : CD12L-0B-020-C0

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RPM and Velocity Sensor

• Supply Voltage: 4.5 - 24 V DC

• Supply Current: 10 mA

• Output Signal: Pulse 0-50 V

• Maximum output current: 20 mA

• Sensing distance: From 0.5 to 2 mm

• Maximum operating Frequency: 100KHz

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Temperature Sensor Result

• Maximum 5% error

• T = m × Io +k

• m = 10418.75

• k = -59.48 C

• Linear Sensor

• V = Io × Rf (Rf=250 ohms)

T= temperaturem = slopek = Temperature offset

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Pressure Sensor Result

• Maximum 5% error

• P = m × Io +k

• m = 6250

• k = -25 C

• Linear Sensor

• V = Io × Rf (Rf=250 ohms)

P = Pressurem = slopek = pressure offset

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RPM Sensor Result

• Maximum 5% error

• F = Frequency

• RPM = F(cycle/sec) (60sec/1min) (1rev/2cycles)

• Linear Sensor

Justin’s Agenda

• Subsystem block diagrams

• Project functional requirements

• Hardware and software used

• Amulet touch screen

• Subsystem test results

• Wireless transmission

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Subsystem Block Diagrams

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Oil Pressure Input

Water Temp Input

MPH Input

RPM Input

Batt. Voltage Input

ATmega128ATmega128

Aerocomm AC4790

Amulet Touchscreen

Home Page

Race Mode

Demo Mode

Practice Mode

Aerocomm AC4790

Project Functional Requirements

• Functional Requirement

• Data acquisition sends data for display

• Display accessible to driver

• Specification

• Data can viewed on the touchscreen

• Can be easily seen by driver without posing as a distraction from driving

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Hardware and Software Used

• Hardware

• Amulet touchscreen

• Laptop

• Atmega128

• Software

• Gemstudio

• Atmel Studio

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Amulet Touchscreen

• Pseudo data used for demo mode

• Aggressive warning system

• Demo mode sweep

• Navigation between modes

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Amulet Display Results

• Aesthetics

• Navigation

• Widgets

• Microcontroller communication

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Home Page

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Practice Mode

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Demo Mode

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Demo Mode

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Race mode

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John's Agenda● Subsystem block diagram

● Project functional requirements

● Hardware & software used

● Wireless transmission testing

● Testing with simulated data

● Interfacing with LabView

● Subsystem test results 32

Subsystem Block Diagram

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Water Temp Input

Oil Pressure Input

MPH Input

RPM Input

Batt. Voltage Input

ATmega128Aerocomm

AC4790

Aerocomm AC4790

LabVIEW Display

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Project Functional Requirements

35

Hardware & Software Used

Hardware

• Atmega128

• Aerocomm AC4790

• Laptop

Software

• Atmel Studio

• HyperTerminal

• LabVIEW

Wireless Transmission Testing

• Board to board

• Board to HyperTerminal

• Microcontroller to HyperTerminal

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• Linear Output• Oil Pressure, Water Temperature, Battery Voltage

• Simulated with Power Supply

• Pulse Output• Tachometer, Speedometer

• Simulated with the Wave Generator

Testing with Simulated Data

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• Communication Protocol

• Universal Asynchronous Receiver/Transmitter(UART)

• Transmission Type

• Ascii

• Sent using packets

Interfacing with LabView

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Subsystem Test Results

• Wireless communication established

• Microcontroller communication with HyperTerminal

• Data displayed is current

• Values displayed in ascii equivalent

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Sean’s Agenda

• Functional requirements

• Subsystem block diagram

• Equipment used

• Interface Amulet with microcontroller

• Prepare LabVIEW to display wireless data

• Results

41

Functional Requirements & Specifications

Functional Requirements

Specifications

Display data to driver and pit crew

Touchscreen display

Store data for review UART communication

Does not interfere with driver performance

5 V power supply

No loose or exposed wires Display real time data

42

Subsystem Block Diagram

Microcontroller

(ATmega128)

Amulet LCD

Data From Wireless

Transceiver

UART

RS-232

Laptop(LabVIEW

GUI)

5V Power Supply

Hardware & Software

Equipment• Amulet LCD

• ATmega128 (microcontroller)

• DC/DC converter (

• Level shifter (+5 [V] to +3.3 [V])

• Laptop

• Oscilloscope

Software• GemStudio Pro (Amulet

display software)

• Atmel Studio 6.1 (microcontroller software)

• LabVIEW 2014

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Amulet Subsystem Bl0ck Diagram

Microcontroller

Put Sensor Data in Array to Transmit

Send Data Array

Amulet Touchscreen

100 ms interrupt

UART

5V Power Supply

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Amulet LCD• Serial Protocol

• UART

• Ascii

• 9600 bps baud rate

• Transmit specific protocol to access variables

• Microcontroller is master

• Initializes communication

• Amulet is slave

• Full Protocol- Responds only if Amulet receives valid message

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Amulet LCD

• Internal RAM (IR) is memory on the Amulet.

• 256 byte variables

• 256 word variables (word = 2 bytes)

• Can receive 14 different command messages from microcontroller

• Can access internal RAM on Amulet

• Changing and copying variables

• Jump to different pages on display

• Draw pixel, line, or box

Amulet Serial Communication Flow Chart

Op-code

Variable Address

(High nibble)

Variable Address

(Low nibble)

Variable Value(High

nibble)

Variable Value(Low

nibble)

Op-code = Tells Amulet what type of variable is being accessed

(byte or word)

Address = The variables location on the RAM of the Amulet LCD

Value = The data to be displayed on the Amulet LCD

Figure 1 – Transmit protocol for a byte variable.

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LabVIEW Subsystem Bl0ck Diagram

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Put Sensor Data in

Transmission Array

Send Array Data

LabVIEWI/O Assistant(Parse Data)

100 ms interrupt

RS-232

Log Data

LabVIEWGauge Display

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LabVIEW Display

• Serial Protocol

• RS-232

• Ascii

• 9600 bps baud rate

• Transmit packets of data

• Instrument I/O Assistant

• Front Panel vs. Block Diagram

• Connect blocks to data type and viewing method

Aerocomm

Transceiver

Laptop(LabVIEW Display)

Instrument I/O

Assistant

Display Data

Save Data

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Front Panel

Serial Communication Setup

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Block Diagram

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Subsystem Results

• Successful interface between ATmega128 and Amulet LCD• Data sent and displayed on the Amulet LCD

• Successful interface between Aerocomm Transceiver and LabVIEW GUI• Data sent, displayed, and stored on the LabVIEW GUI

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System Test Results

• Display data to driver with aggressive notification system

• Race, demo, and practice modes

• Wirelessly send data to pit crew’s laptop to be displayed on LabVIEW

• Data logged via LabVIEW

• Sensor’s acquire data with max error under 5%

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Summary & Conclusion

• BU ME’s require more advanced notification system for driver

• Requires data logging, multiple display modes, and wireless transmission

• System is functional

• Requires installation and further testing

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Sources

• http://cegt201.bradley.edu/projects/proj2011/pjacher/SAEDAQ/Deliverables_files/SAEDAQ_final_report.pdf

• http://www.atmel.com/images/doc2467.pdf

• http://www.amulettechnologies.com/images/stories/Downloads/mk480272cdatasheet1112.pdf

• https://www.dropbox.com/s/l8abp41iru83oqg/Datasheet_carspd_eng_101.pdf?dl=0

• http://www.automationdirect.com/static/specs/prosensettrans.pdf

• http://www.automationdirect.com/static/specs/prosensetransmitters.pdf

Appendix

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Initialization

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ISR

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.C/.h files

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to_ascii

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Amulet Ascii Transmit Protocol Example

MicrocontrollerSet Byte Variable

Amulet Response

MicrocontrollerSet Word Variable

Amulet Response

Figure 2 – Serial communication flow chart 63

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Amulet Protocol AsciiExample: microcontroller sets internal RAM (IR) word variable to specific value (0x02C9)

Figure 3 – Serial communication flow chart

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UART Transmit

• 1V per division

• 0.5ms per division

• Transmission contains:

{0x00, 0xD6, 0x31}

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Maximum data log time

• Limited by max rows in excel• Max rows about 1 million

• Log data every 100 [ms]

• Max time = 27.8 hours

• 0.1 [sec/row] *1.2E6 [rows] = 100,000 sec

• 100,000 [sec] /60 [sec/min] /60 [min/hr] = 27.8 hrs

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Max Transmission Rate with 9600 bps Baud Rate

• 1 bit sending time:

• 1/9600 = 104 us

• Assume 16 byte packet

• 8 bits + 1 start_bit + 1 stop_bit = 10 bits/byte_sent

• 104 [us/bit] * 10 [bits/byte] * 16 [bytes/packet] = 16.6 [ms/packet]

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Research

• Amulet serial communication protocol

• LabVIEW Instrument I/O Assistant

• Troubleshooting errors

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