ATV INSTRUMENTATIONDISPLAY

System Design

Ed RaezerSenior Project

Western WashingtonUniversity

Desired Functions Speedometer

0-99 MPH 1 MPH Resolution

Tachometer 0-12000 RPM 100 RPM Resolution

Odometer 0-9999.9 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

3.57KR8

1.02KR9

D1

D2

ComparatorU2

1.02kR12Splice into

Pulse Signal

+5V

DG

ND

+5V

DGND

+5V

MAX931

+

-

IN-

IN+

V-

GND

HYST

REF

V+

OUT

4

3

2

1

5

6

7

8

-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

0V

5V

t

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

MODE

LCD DISPLAY

PUSH BUTTONS

LEDS

10 Seg. LED

BARGRAPH

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 & Priorities4- Start Task5- Clock Task6- U.I. Task7- Button Monitor Task8- RPM Task9- Speed Task

Start TaskDescription:

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

Clock TaskDescription:

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

User Interface TaskDescription:

-Reacts to button presses-Clock Setting-Activates LEDs-Changes Display Modes-Displays data on LCD Display

RPM TaskDescription:

-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 TaskDescription:

-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 DiagramReed Switch

Ignition Pulse

Pulse Accum.

RPMTask

RPM Buffer

UserInterface

Task

LCD Display

Clock Task

CloickBuffer

Speed Task

Speed Buffer

OdometerBuffer

Physical MCUDisplays

ISR Rotation Counter

LED Bargraph

User Interface State Diagram

SPEED XX MPH

CLOCK XX:XX:XX

SPEED XX MPH

TACH XXXXX RPM

SPEED XX MPH

ODOM XXXXX MILES

RESETODOMETER

UP + DOWN

MODE

MODE

MODE

START

SET CLOCK

UP +DOWN

UP + DOWN

Prototype

Learning Process Leave time for the unexpected Teamwork

Questions?

Thank You For Your Time