ATV INSTRUMENTATION DISPLAY System Design Ed Raezer Senior Project Western Washington University

Desired Functions  Speedometer 0-99 MPH 1 MPH Resolution  Tachometer RPM 100 RPM Resolution  Odometer Miles 0.1 Mile Resolution  Clock 12 Hour Clock HH:MM:SS

Designing “To Do” List  Hardware Which MCU to use? How to interface system with ATV? What to use for user interface?  Software Which software kernel to use? What tasks are needed? How much memory needed?

MicroController Choice  Motorola MC9S12C32 32k Bytes EEPROM, 2K Bytes RAM  Estimated Memory Needed 8k Bytes EEPROM, 1.5K Bytes RAM  26 I/O Ports

Interfacing with ATV for RPMs

RPM Readings -1.7Vpk pulse generated every engine rotation. -Needed to be converted to a digital 0-5V square wave signal so the MCU could read it. RPM Sensing circuit

Wheel Rotation  Magnetic Reed switch  Magnet mounted on brake rotor trips switch every rotation  Creates a 0-5V square wave

User Interface  2x16 LCD Display Large Characters W/ backlight  Shift Light Green LED  Redline Light Red LED  RPM LED Bargraph  3 Pushbuttons

Schematic

Kernel Selection  Kernel Choice: MicroC/OS-II Real-time preemptive multitasking kernel with a 1 ms tick period  Configured for my program Modify (os_cfg.h)

Task Needed & Priorities 4- Start Task 5- Clock Task 6- U.I. Task 7- Button Monitor Task 8- RPM Task 9- Speed Task

Start Task Description: -Initializations: LCD, Keys, OSTick -Intialize Port Directions and Initial Values -Creates Tasks -Priority #4 -Period: once (at startup)

Clock Task Description: -Keeps time using a software clock -Runs timer for speed task -Updates time buffer -Period: 10 msec (Periodic)

User Interface Task Description: -Reacts to button presses -Clock Setting -Activates LEDs -Changes Display Modes -Displays data on LCD Display

RPM Task Description: -Retrieves pulse count from pulse accumulator every 600 msec and converts to RPMs -Updates RPM buffer. -Controls LED Bargraph -Period: 600 msec (periodic)

ISR  Interrupt caused by input from wheel rotation sensor  Counter incremented every time wheel makes one rotation.  Period: Dependent on speed of ATV

Speed Task Description: -Every 5 wheel rotations, speed is calculated using timer ran in the clock task. -Unless 3 secs. have elapsed, then speed is calculated using # of tire rotations in that 3 second period. -Updates odometer -Updates speed buffer

Dataflow Diagram

User Interface State Diagram

Prototype

Learning Process  Leave time for the unexpected  Teamwork

Questions?  Thank You For Your Time