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SAE Formula Car Display and Data Acquisition System “SAEDAQ”

SAE Formula Car Display and Data Acquisition System “SAEDAQ”. Caleb Davison Phil Jacher George Kontos Advisor: Mr. Gutschlag. Overview. Summary Measurement Strategies LabVIEW User Interface Microcontroller LCD Screen Wireless Chips. Overview. Summary Measurement Strategies

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SAE Formula Car Display and Data Acquisition System “SAEDAQ”

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  1. SAE Formula Car Display and Data Acquisition System “SAEDAQ” Caleb Davison Phil Jacher George Kontos Advisor: Mr. Gutschlag

  2. Overview • Summary • Measurement Strategies • LabVIEW User Interface • Microcontroller • LCD Screen • Wireless Chips

  3. Overview • Summary • Measurement Strategies • LabVIEW User Interface • Microcontroller • LCD Screen • Wireless Chips

  4. A Typical Car…

  5. SAEDAQ Summary • Society of Automotive Engineers Formula One racecar • Data recording • wheel speed • engine rpm • oil pressure • oil temperature • coolant temperature • Data will be transmitted to the car’s dashboard and an off-track laptop

  6. Previous Works • Project has been attempted several times • Never been able to coordinate with MEs • Most recently last year with Justin Peters • Using different MCU, upgraded wireless chips • New dashboard design

  7. High Level Block Diagram

  8. Overview • Summary • Measurement Strategies • LabVIEW User Interface • Microcontroller • LCD Screen • Wireless Chips

  9. Temperature and Pressure • Temperature sensor (0-300 degrees Fahrenheit) x 2 • Pressure sensor (0-100 psi) x 1 • Requires supply voltage (12V) • Outputs current (4-20mA)

  10. Sensor Measurement Circuit • From datasheet: ZLmax=(Vs-9.6)*50 • Vs=12V from car battery, ZLmax =120 ohms • Issue: at 20mA, A/D voltage will be only 2.4V • Solution: Adjust A/D resolution (0-2.56V)

  11. A/D Method - Temperature

  12. Linear Based Method • Temp=(1.5625*A/D Value)-75 • Attempt 1: Temp=((A/D Value*3)/2)-75 • Attempt 2: Temp=((A/D Value*1563)/1000)-75 • Solution: Look up table, use memory available

  13. A/D Method - Pressure

  14. Linear Based Method • Temp=(0.5208*A/D Value)-25 • Attempt 1: Temp=(A/D Value/2)-75 • Solution: Look up table, use memory available

  15. Engine RPM Measurement • ACI Hall-effect current sensor • TTL output • Induced supply power • Meets amperage range

  16. Overview • Summary • Measurement Strategies • LabVIEW User Interface • Microcontroller • LCD Screen • Wireless Chips

  17. LabVIEW Interfacing: Front Panel

  18. LabVIEW Interfacing: Front Panel

  19. LabVIEW Interfacing: Front Panel (cont.) • RS232 communication protocol • Complete control over settings • Data logging feature

  20. LabVIEW Interfacing: Front Panel (cont.)

  21. LabVIEW Interfacing: Front Panel (cont.) • Pressure and temperature updated in real time along with engine RPM and speed • Warning lights indicate dangerous levels

  22. LabVIEW Interfacing: Front Panel (cont.)

  23. LabVIEW Interfacing: Front Panel (cont.) • Data vs time displays operate independently

  24. LabVIEW Interfacing: Parallel Computing

  25. Overview • Summary • Sensors • LabVIEW User Interface • Microcontroller • LCD Screen • Wireless Chips

  26. Microcontroller: AmtelATmega 128 MCU 16 MHz clock 8 A/D converters Voltage regulator (5.5-15V) Dual UARTS Additional power and ground connectors

  27. Programming Phases • A/D Converter • RS-232 Interface • RPM Counter • Touchscreen • All Together

  28. Programming Phases • A/DConverter • RS-232 Interface • RPM Counter • Touchscreen • All Together

  29. A/D Conversion • Records oil pressure, oil temperature, and coolant temperature • A/D inputs: 0-2.56V • Sensor voltages: 0.48-2.4V • Scaled into single byte value

  30. A/D Conversion ADC clock machine cycle: 8us 1st conversion: 200us Normal conversions: 104us Three conversions: 312us Vref = 2.56 V

  31. Programming Phases • A/D converter • RS-232 Interface • RPM Counter • Touchscreen • All Together

  32. RS-232 Interfacing • Previous experience with transmit/receive • Stair step progress: • Polling • Interrupt driven • Timer based

  33. RS-232 Interfacing • Hyper Terminal problems • Incorrect Hyper Terminal settings • ASCII Setup – echo typed characters locally • Transmitting/Receiving settings: • 9600 baud • 8 data bits • 1 stop bit

  34. Example RS-232 Communication • Receive key press from computer • ASCII ‘F’ sent back to computer • Hyper Terminal displays appropriate values

  35. Example RS-232 Communication • String based communication with timer • Sends “1abcde” every 5 seconds • Practical application

  36. Programming Phases • A/D Converter • RS-232 Interface • RPM Counter • Touchscreen • All Together

  37. Example simulation Set up basic pulse counting program 100ms (10 Hz) sampling period Counts rising edges 30 Hz Pulse Input RPM Counter

  38. RPM Counter • Problems with 16-bit counter • Had to use external interrupts • Rising edge triggers interrupt • Counter increments • Inefficient

  39. Programming Phases • A/D Converter • RS-232 Interface • RPM Counter • Touchscreen • All Together

  40. Touchscreen • ASCII protocol • CRC protocol • Used XON/XOFF to simplify

  41. XON/XOFF Communication

  42. ASCII Protocol • Set byte variable 1 to 0xFE • Set IR word variable 0 to 0x02C9 Opcode Internal RAM address Internal RAM value

  43. Jump to Page Function • Does not use the normal ASCII protocol • Reads in hexadecimal format • Jump to page 0x103: • Opcode • Internal RAM address • Internal RAM value

  44. Calculating the Checksum Value • X=0xA0+0x02+0x01+0x03=0xA6 • The sums of the LSB must be 0xNN00 • 0x100-0xA6=0x5A

  45. Programming Phases A/D Converter RS-232 Interface RPM Counter Touchscreen All Together

  46. All Together

  47. Software Flowchart

  48. Overview Summary Sensors LabVIEW User Interface Microcontroller LCD Screen Wireless Chips

  49. Touchscreen Amulet Technologies GEMStudio µHTML 9600 Baud Resistive technology LCD GUI from 2010 Project

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